%%% ---------------------------------------------------------------------- %%% BibTeX-file { %%% author = "{Electronic Visualization Library Service}", %%% filename = "EVL-1999.bib", %%% address = "Konrad-Zuse-Zentrum f{\"u}r %%% Informationstechnik Berlin (ZIB) %%% Scientific Visualization Department %%% Takustr. 7 %%% 14195 Berlin %%% Germany", %%% URL = "http://visinfo.zib.de/EVlib/", %%% email = "davis@zib.de", %%% supported = "yes", %%% docstring = "This file contains the complete bibliography of %%% references submitted to the %%% Electronic Visualization Library for the year 1999.", %%% } @Book{EVL-1999-1, year = "1999", title = "Graph Drawing: Algorithms for the Visualization of Graphs", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-1", author = "Ioannis G. Tollis and Giuseppe Di Battista and Peter Eades and Roberto Tamassia", abstract = "This book is designed to describe fundamental algorithmic techniques for constructing drawings of graphs. Suitable as a book or reference manual, its chapters offer an accurate, accessible reflection of the rapidly expanding field of graph drawing.", language = "en", copyright = "Prentice Hall", publisher = "Prentice Hall", } @Article{EVL-1999-10, pages = "21--35", year = "1999", title = "Robust retrieval of three-dimensional structures from image stacks", author = "M. Garza-Jinich and P. Meer and V. Medina", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-10", language = "en", abstract = "Robust high-breakdown-point location estimators are employed to analyze image stacks under the piecewise constant image structure model. To reduce the effect of bias along the Z-axis, the class parameters are extracted using three consecutive slices. The segmentation algorithm first determines the most reliable seed regions, which are then used in a region-growing procedure supported by local evidence. The robustness and stability of the proposed technique is shown with both synthetic and real data, the latter consisting of one MRI and one confocal microscopy set. The performance of the algorithm is consistent with the ground truth obtained with manual segmentation by physicians.", keywords = "confocal microscope images, image segmentation, magnetic resonance images robust statistics", volume = "3", number = "1", journal = "Medical Image Analysis", } @TechReport{EVL-1999-100, year = "1999", title = "Thermalization of Large Fluid Systems consisting of Lennard-Jones Mixtures", author = "M. Hloucha", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-100", abstract = "This document describes a method for the creation of thermally equilibrated molecular configurations for large scale molecular dynamics simulations and its parallel implementation. The method combines relaxation of a stochastic initial configuration by Monte Carlo moves followed by molecular dynamics. Benchmarks are presented for up to 800000 particles.", month = feb, number = "FZJ-ZAM-IB-9902", institution = "Forschungszentrum J{\"{u}}lich, Central Institue for Applied Mathematics (ZAM)", } @Article{EVL-1999-101, pages = "11--29", year = "1999", title = "Compression Methods for Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-101", author = "M. H. Gross and L. Lippert and O. Staadt", abstract = "Compression methods have become of fundamental importance in almost every subfield of scientific visualization. However, unlike image compression, advanced visualization applications impose manifold constraints on the design of appropriate algorithms, where progressiveness, multiresolution or topology preservation are some of the key issues. This paper demonstrates the importance of multiresolution compression methods for visualization using two examples: The first, compression domain volume rendering, enables one to visualize volume data progressively and instantaneously from its compressed data format and is designed for WWW and networked applications. The second one is a multiresolution compression and reconstruction method that allows for progressive coding, transmission and geometric reconstruction of surfaces and volumes. Both of the presented methods are so-called transform coding schemes and use wavelets for data representation.", month = mar, volume = "15", keywords = "visualization, compression, wavelets, volume rendering", number = "1", journal = "Future Generation Computer Systems", } @TechReport{EVL-1999-102, year = "1999", title = "Construction of Multiresolution Triangular {B}-Spline Surfaces using Hexagonal Filters", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-102", author = "A. Dreger and M. H. Gross and J. Schlegel", abstract = "We present multiresolution B-spline surfaces of arbitrary order defined over triangular domains. Unlike existing methods, the basic idea of our approach is to construct the triangular basis functions from their tensor product relatives in the spirit of box splines by projecting them onto the barycentric plane. The scheme works for splines of any order where the fundamental building blocks of the surface are hierarchies of triangular B-spline scaling functions and wavelets spanning the complement spaces between levels of different resolution. Although our bases functions have been deduced from the corresponding 3D-bases, our decomposition and reconstruction scheme operates directly on the triangular mesh using hexagonal filters. The resulting basis functions are used to approximate triangular surfaces and provide many useful properties, such as multiresolution editing, local level of detail, continuity control, surface compression and much more. The performance of our approach is illustrated by various examples including parametric and nonparametric surface editing and compression.", month = jul, keywords = "Triangular B-spline wavelets, box splines, multiresolution editing, hierarchical surface representation, surface compression, decomposition, reconstruction", number = "327", institution = "Computer Science Department, Institute of Scientific Computing, ETH Z{\"{u}}rich", } @TechReport{EVL-1999-103, year = "1999", title = "A Framework for Facial Surgery Simulation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-103", author = "M. Koch and S. H. M. Roth and M. H. Gross and A. P. Zimmermann and H. F. Sailer", abstract = "The accurate prediction of the post-surgical facial shape is of paramount importance for surgical planning in facial surgery. In this paper we present a framework for facial surgery simulation which is based on volumetric finite element modeling. We contrast conven-tional procedures for surgical planning against our system by accompanying a patient during the entire process of planning, medical treatment and simulation. In various preprocessing steps a 3D physically based facial model is reconstructed from CT and laser range scans. All geometric and topological changes are modeled interactively using Alias.ª Applying fully 3D volumetric elasticity allows us to represent important volumetric effects such as incompressibility in a natural and physically accurate way. For computational effi-ciency, we devised a novel set of prismatic shape functions featuring a globally C 1 -continuous surface in combination with a C 0 interior. Not only is it numerically accurate, but this construction enables us to compute smooth and visually appealing facial shapes. An extended evaluation and quantitative analysis of a clinical test series with several female and male patients clearly demonstrates the per-formance of our framework.", month = jun, keywords = "Finite Element Method, Facial Surgery Simulation, Facial Modeling, Data Reconstruction", number = "326", institution = "Institute of Scientific Computing, Computer Science Department, ETH Z{\"{u}}rich", } @InProceedings{EVL-1999-104, pages = "291--300", year = "1999", title = "{V}isualization {T}echniques for {T}ime-{O}riented, {S}keletal {P}lans in {M}edical {T}herapy {P}lanning", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-104", author = "Robert Kosara and Silvia Miksch", abstract = "In order to utilize elaborate tools and techniques (like verification) for use with clinical protocols, these must be represented in an appropriate way. Protocols are typically represented by means of formal languages (e.g., Asbru), which are very hard to understand for medical experts and lead to many problems in practical use. Therefore, a powerful user interface is needed. We identify the key problems the user-interface designer is faced with, and present a number of ``classic'' solutions and their shortcomings --- which led to our own solution called AsbruView. Its two different views (Topological View and Temporal View) are presented.", month = jun, address = "Aalborg, Denmark", editor = "Werner Horn and Yuval Shahar and Greger Lindberg and Steen Andreassen and Jeremy Wyatt", booktitle = "Proceedings of the Joint European Conference on Artificial Intelligence in Medicine and Medical Decision Making (AIMDM'99)", publisher = "Springer Verlag", } @MastersThesis{EVL-1999-105, year = "1999", title = "{M}etaphors of {M}ovement --- {A} {U}ser {I}nterface for {M}anipulating {T}ime-{O}riented, {S}keletal {P}lans", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-105", author = "Robert Kosara", abstract = "This thesis introduces a user interface that supports the understanding and manipulation of time-oriented, skeletal plans. This user interface is called AsbruView, and is based on the plan representation language Asbru, which is used for medical therapy planning. Clinical protocols are seen in Asbru as time-oriented, skeletal plans. AsbruView utilizes Metaphors of running tracks and traffic control to communicate important concepts and uses glyphs to depict the complex time annotations used in Asbru. Two different views show different aspects of the same set of plans: One shows the topology of plans and which parts have been defined, the other captures the temporal dimension and the structure of plans. We present a number of existing visualization approaches to different problems that we faced and discuss their usefulness for our purpose. We also show why we did not use a knowledge acquisition tool for editing Asbru plans. We have evaluated AsbruView with six domain experts (physicians), who judged it as usable and easy to understand. The findings of that evaluation are presented and discussed.", month = may, school = "Vienna University of Technology, Vienna, Austria", } @Article{EVL-1999-106, year = "1999", title = "Locally Toleranced Surface Simplification", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-106", author = "Andr{\'{e}} Gu{\'{e}}ziec", abstract = "We present a technique for simplifying a triangulated surface. Simplifying consists of approximating the surface with another surface of lower triangle count. Our algorithm can preserve the volume of a solid to within machine accuracy; it favors the creation of near-equilateral triangles. We develop novel methods for reporting and representing a bound to the approximation error between a simplified surface and the original, and respecting a variable tolerance across the surface. A different positive error value is reported at each vertex. By linearly blending the error values in between vertices, we define a volume of space, called the error volume, as the union of balls of linearly varying radii. The error volume is built dynamically as the simplification progresses, on top of preexisting error volumes that it contains. We also build a tolerance volume to forbid simplification errors exceeding a local tolerance. The information necessary to compute error values is local to the star of a vertex; accordingly, the complexity of the algorithm is either linear or in O(n log n) in the original number of surface edges, depending on the variant. We extend the mechanisms of error and tolerance volumes to preserve during simplification scalar and vector attributes associated with surface vertices. Assuming a linear variation across triangles, error and tolerance volumes are defined in the same fashion as for positional error. For normals, a corrective term is applied to the error measured at the vertices to compensate for nonlinearities.", month = apr, volume = "5", keywords = "Surface simplification, error volume, tolerance volume", number = "2", journal = "IEEE Transactions on Visualization and Computer Graphics", } @Article{EVL-1999-107, year = "1999", title = "Feature Extraction of Separation and Attachment Lines", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-107", author = "David N. Kenwright and Chris Henze and Creon Levit", abstract = "Separation and attachment lines are topologically significant curves that exist on 2D surfaces in 3D vector fields. Two algorithms are presented, one point-based and one element-based, that extract separation and attachment lines using eigenvalue analysis of a locally linear function. Unlike prior techniques based on piecewise numerical integration, these algorithms use robust analytical tests that can be applied independently to any point in a vector field. The feature extraction is fully automatic and suited to the analysis of large-scale numerical simulations. The strengths and weaknesses of the two algorithms are evaluated using analytic vector fields and also results from computational fluid dynamics (CFD) simulations. We show that both algorithms detect open separation lines--a type of separation that is not captured by conventional vector field topology algorithms.", month = apr, volume = "5", keywords = "vector field visualization, vector field topology, flow visualizaiton, feature detection, flow separation, separation line", number = "2", journal = "IEEE Transactions on Visualization and Computer Graphics", } @Article{EVL-1999-108, year = "1999", title = "Evaluation of Memoryless Simplification", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-108", author = "Peter Lindstrom and Greg Turk", abstract = "This paper investigates the effectiveness of the Memoryless Simplification approach described by Lindstrom and Turk. Like many polygon simplification methods, this approach reduces the number of triangles in a model by performing a sequence of edge collapses. It differs from most recent methods, however, in that it does not retain a history of the geometry of the original model during simplification. We present numerical comparisons showing that the memoryless method results in smaller mean distance measures than many published techniques that retain geometric history. We compare a number of different vertex placement schemes for an edge collapse in order to identify the aspects of the Memoryless Simplification that are responsible for its high level of fidelity. We also evaluate simplification of models with boundaries, and we show how the memoryless method may be tuned to trade between manifold and boundary fidelity. We found that the memoryless approach yields consistently low mean errors when measured by the Metro mesh comparison tool. In addition to using complex models for the evaluations, we also perform comparisons using a sphere and portions of a sphere. These simple surfaces turn out to match the simplification behaviors for the more complex models that we used.", month = apr, volume = "5", keywords = "Model simplification, surface approximation, level of detail, geometric error, optimization", number = "2", journal = "IEEE Transactions on Visualization and Computer Graphics", } @Article{EVL-1999-109, year = "1999", title = "High-Quality Splatting on Rectilinear Grids with Efficient Culling of Occluded Voxels", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-109", author = "Klaus Mueller and Naeem Shareef and Jian Huang and Roger Crawfis", abstract = "Splatting is a popular volume rendering algorithm that pairs good image quality with an efficient volume projection scheme. The current axis-aligned sheet-buffer approach, however, bears certain inaccuracies. The effect of these is less noticeable in still images, but clearly revealed in animated viewing, where disturbing popping of object brightness occurs at certain view angle transitions. In previous work, we presented a new variant of sheet-buffered splatting in which the compositing sheets are oriented parallel to the image plane. This scheme not only eliminates the condition for popping, but also produces images of higher quality. In this paper, we summarize this new paradigm and extend it in a number of ways. We devise a new solution to render rectilinear grids of equivalent cost to the traditional approach that treats the anisotropic volume as being warped into a cubic grid. This enables us to use the usual radially symmetric kernels, which can be projected without inaccuracies. Next, current splatting approaches necessitate the projection of all voxels in the iso-interval(s), although only a subset of these voxels may eventually be visible in the final image. To eliminate these wasteful computations we propose a novel front-to-back approach that employs an occlusion map to determine if a splat contributes to the image before it is projected, thus skipping occluded splats. Additional measures are presented for further speedups. In addition, we present an efficient list-based volume traversal scheme that facilitates the quick modification of transfer functions and iso-values.", month = apr, volume = "5", keywords = "splatting, volume rendering, visualization, rectilinear grids", number = "2", journal = "IEEE Transactions on Visualization and Computer Graphics", } @Article{EVL-1999-11, pages = "39--63", year = "1999", title = "Model-based detection of spiculated lesions in mammograms", author = "R. Zwiggelaar and T. C. Parr and I. W. Hutt and C. J. Taylo and S. M. Astley and C. R. M. Boggis", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-11", language = "en", abstract = "Computer-aided mammographic prompting systems require the reliable detection of a variety of signs of cancer. In this paper we concentrate on the detection of spiculated lesions in mammograms. A spiculated lesion is typically characterized by an abnormal pattern of linear structures and a central mass. Statistical models have been developed to describe and detect both these aspects of spiculated lesions. We describe a generic method of representing patterns of linear structures, which relies on the use of factor analysis to separate the systematic and random aspects of a class of patterns. We model the appearance of central masses using local scale-orientation signatures based on recursive median filtering, approximated using principal-component analysis. For lesions of 16 mm and larger the pattern detection technique results in a sensitivity of 80% at 0.014 false positives per image, whilst the mass detection approach results in a sensitivity 80% at 0.23 false positives per image. Simple combination techniques result in an improved sensitivity and specificity close to that required to improve the performance of a radiologist in a prompting environment.", keywords = "central mass detection, mammogram, oriented line patterns, spiculated lesions", volume = "3", number = "1", journal = "Medical Image Analysis", } @Article{EVL-1999-110, year = "1999", title = "Large Datasets at a Glance: Combining Textures and Colors in Scientific Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-110", author = "Christopher G. Healey and James T. Enns", abstract = "This paper presents a new method for using texture and color to visualize multivariate data elements arranged on an underlying height field. We combine simple texture patterns with perceptually uniform colors to increase the number of attribute values we can display simultaneously. Our technique builds multicolored perceptual texture elements (or pexels) to represent each data element. Attribute values encoded in an element are used to vary the appearance of its pexel. Texture and color patterns that form when the pexels are displayed can be used to rapidly and accurately explore the dataset. Our pexels are built by varying three separate texture dimensions: height, density, and regularity. Results from computer graphics, computer vision, and human visual psychophysics have identified these dimensions as important for the formation of perceptual texture patterns. The pexels are colored using a selection technique that controls color distance, linear separation, and color category. Proper use of these criteria guarantees colors that are equally distinguishable from one another. We describe a set of controlled experiments that demonstrate the effectiveness of our texture dimensions and color selection criteria. We then discuss new work that studies how texture and color can be used simultaneously in a single display. Our results show that variations of height and density have no effect on color segmentation, but that random color patterns can interfere with texture segmentation. As the difficulty of the visual detection task increases, so too does the amount of color on texture interference increase. We conclude by demonstrating the applicability of our approach to a real-world problem, the tracking of typhoon conditions in Southeast Asia.", month = apr, volume = "5", keywords = "color, color category, experimental design, human vision, linear separation, multivariate dataset, perception, pexel, preattentive processing, psychophysics, scientific visualization, texture, typhoon", number = "2", journal = "IEEE Transactions on Visualization and Computer Graphics", } @Article{EVL-1999-111, pages = "221--246", year = "1999", title = "Interval Reductions and Extensions of Orders: Bijections to Chains in Lattices", author = "Stefan Felsner and Jens Gustedt and Michel Morvan", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-111", volume = "15", journal = "Order", } @TechReport{EVL-1999-113, year = "1999", title = "Distributed Lighting Networks", author = "P. Kipfer", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-113", abstract = "A case study of application-oriented distribution patterns on the Vision system.", number = "3", institution = "Universit{"}at Erlangen-N{"}urnberg, Lehrstuhl f{\"{u}}r Graphische Datenverarbeitung", } @TechReport{EVL-1999-114, year = "1999", title = "Interactive Direct Volume Rendering of Dural Arteriovenous Fistulae", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-114", author = "C. Rezk--Salama and P. Hastreiter and K. Eberhardt and B. Tomandl and T. Ertl", note = "submitted to MICCAI'99", number = "4", institution = "Universit{"}at Erlangen-N{"}urnberg, Lehrstuhl f{\"{u}}r Graphische Datenverarbeitung", } @TechReport{EVL-1999-115, year = "1999", title = "Virtual Labyrinthoscopy: Visualization of the Inner Ear with Interactive Direct Volume Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-115", author = "B. Tomandl and P. Hastreiter and K. Eberhardt and H. Greess and U. Nissen", number = "5", institution = "Universit{"}at Erlangen-N{"}urnberg, Lehrstuhl f{\"{u}}r Graphische Datenverarbeitung", } @TechReport{EVL-1999-116, year = "1999", title = "Virtual Endoscopic {CT} Angiography ({VECTA}): Value of Perspective Volume Rendering for the Visualization and Therapy Planning of Intracranial Aneurysms", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-116", author = "B. Tomandl and K. Eberhardt and P. Hastreiter and M. Buchfelder and T. Ertl", number = "6", institution = "Universit{"}at Erlangen-N{"}urnberg, Lehrstuhl f{\"{u}}r Graphische Datenverarbeitung", } @TechReport{EVL-1999-117, year = "1999", title = "Registration and Visualization of Multimodal Image Data", author = "P. Hastreiter and T. Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-117", number = "10", institution = "Universit{"}at Erlangen-N{"}urnberg, Lehrstuhl f{\"{u}}r Graphische Datenverarbeitung", } @InProceedings{EVL-1999-118, year = "1999", title = "Remote 3{D} Visualization using Image-Streaming Techniques", author = "Klaus Engel and Ove Sommer and Christian Ernst and Thomas Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-118", booktitle = "Proceedings of the International Symposium on Intelligent Multimedia and Distance Education", } @InProceedings{EVL-1999-119, pages = "192--196", year = "1999", title = "Interactive Direct Volume Rendering of the Inner Ear for the Planning of Neurosurgery", author = "P. Hastreiter and C. Rezk--Salama and B. Tomandl and K. Eberhard and T. Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-119", booktitle = "Proc. Worksh. Bildverarbeitung f{"}ur die Medizin (BVM)", publisher = "Springer", } @Article{EVL-1999-12, pages = "77--101", year = "1999", title = "Knowledge-based tensor anisotropic diffusion of cardiac magnetic resonance images", author = "G. I. Sanchez-Ortiz and D. Rueckert and P. Burger", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-12", language = "en", abstract = "We present a general formulation for a new knowledge-based approach to anisotropic diffusion of multi-valued and multi-dimensional images, with an illustrative application for the enhancement and segmentation of cardiac magnetic resonance (MR) images. In the proposed method all available information is incorporated through a new definition of the conductance function which differs form previous approaches in two aspects. First, we model the conductance as an explicit function of time and position, and not only of the differential structure of the image data. Inherent properties of the system (such as geometrical features or non-homogeneous data sampling) can therefore be taken into account by allowing the conductance function to vary depending on the location in the spatial and temporal coordinate space. Secondly, by defining the conductance as a second-rank tensor, the non-homogeneous diffusion equation gains a truly anisotropic character which is essential to emulate and handle certain aspects of complex data systems. The method presented is suitable for image enhancement and segmentation of single- or multi-valued images. We demonstrate the efficiency of the proposed framework by applying it to anatomical and velocity-encoded cine volumetric (4-D) MR images of the left ventricle. Spatial and temporal a priori knowledge about the shape and dynamics of the heart is incorporated into the diffusion process. We compare our results to those obtained with other diffusion schemes and exhibit the improvement in regions of the image with low contrast and low signal-to-noise ratio.", keywords = "anisotropic diffusion, geometry-driven diffusion, left-ventricle modelling, phase-sensitive MR, segmentation", volume = "3", number = "1", journal = "Medical Image Analysis", } @InProceedings{EVL-1999-120, year = "1999", title = "A Warping-based Refinement of Lumigraphs", author = "Wolfgang Heidrich and Hartmut Schirmacher and Hendrik K{\"u}ck and Hans-Peter Seidel", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-120", editor = "N. Thalmann and V. Skala", booktitle = "Proc. WSCG '99", } @InProceedings{EVL-1999-121, year = "1999", title = "Applications of Pixel Textures in Visualization and Realistic Image Synthesis", author = "W. Heidrich and R. Westermann and H.-P. Seidel and T. Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-121", organization = "ACM/Siggraph", booktitle = "ACM Symposium on Interactive 3D Graphics", } @InProceedings{EVL-1999-122, year = "1999", title = "Non-linear Registration of Pre- and Intraoperative Volume Data Based On Piecewise Linear Transformations", author = "C. Rezk-Salama and P. Hastreit and G. Greiner and T. Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-122", note = "accepted for publication", booktitle = "Proc. Erlangen Workshop of Vision, Modelling, and Visualization (VMV)", } @Article{EVL-1999-123, pages = "233--244", year = "1999", title = "An Interactive Visualization and Navigation Tool for Medical Volume Data", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-123", author = "O. Sommer and A. Dietz and R. Westermann and T. Ertl", note = "ISSN 0097-8493", number = "2", journal = "Computers & Graphics", } @InProceedings{EVL-1999-124, year = "1999", title = "Virtual Labyrinthoscopy: Visualization of the Inner Ear with Interactive Direct Volume Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-124", author = "B. Tomandl and P. Hastreiter and K. Eberhardt and H. Greess and U. Nissen", note = "accepted for publication in Jan. 2000", booktitle = "RadioGraphics", } @InProceedings{EVL-1999-125, pages = "45--56", year = "1999", title = "Decoupling Polygon Rendering from Geometry using Rasterization Hardware", author = "Ruediger Westermann and Ove Sommer and Thomas Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-125", organization = "Eurographics", note = "ISBN 3-211-83382-X", editor = "D. Lischinski and G. W. Larson", booktitle = "Rendering Techniques '99", publisher = "Springer-Verlag, Wien, New York", } @Article{EVL-1999-13, pages = "63--75", year = "1999", title = "Evaluating a robust contour tracker on echocardiographic sequences", author = "G. Jacob and J. A. Noble and M. Mulet-Parada and A. Blake", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-13", language = "en", abstract = "In this paper we present an evaluation of a robust visual image tracker on echographic image sequences. We show how the tracking framework can be customized to define an appropriate shape space that describes heart shape deformations that can be learned from a training dataset. We also investigate energy-based temporal boundary enhancement methods to improve image feature measurement. Results are presented demonstrating real-time tracking on normal heart motion data sequences and abnormal synthesized and real heart motion data sequences. We conclude by discussing some of our current research efforts.", keywords = "2-D+T ultrasound, echocardiography, energy filters, heart wall motion, real-time tracking", volume = "3", number = "1", journal = "Medical Image Analysis", } @TechReport{EVL-1999-14, year = "1999", title = "Efficient image retrieval through vantage objects", author = "J. Vleugels and R. C. Veltkamp", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-14", abstract = "We describe a new indexing structure for general image retrieval that relies solely on a distance function giving the similarity between two images. For each image object in the database, its distance to a set of m predetermined vantage objects is calculated; the m-vector of these distances specifies a point in the m-dimensional vantage space. The database objects that are similar (in terms of the distance function) to a given query object can be determined by means of an efficient nearest-neighbor search on these points. We demonstrate the viability of our approach through experimental results obtained with a database of about 40.000 hieroglyphic polylines.", number = "UU-CS-1999-01", institution = "Department of Computer Science, Utrecht University", } @Article{EVL-1999-144, pages = "817--835", year = "1999", title = "Using Farin Points for Rational Bezier Surfaces", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-144", author = "Holger Theisel", month = sep, volume = "16", number = "8", journal = "Computer Aided Geometric Design", } @InProceedings{EVL-1999-145, pages = "89--102", year = "1999", title = "Fast Volume rendering methods for voxel-based 2{D}/3{D} registration - {A} comparative study", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-145", author = "Roland G{\"{o}}cke and Heidrun Schumann", booktitle = "Proceedings Biomedical Image Registration, WBIR´99", } @Article{EVL-1999-146, year = "1999", title = "Demand-driven Image Transmission with Levels of Detail and Regions of Interest", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-146", author = "Uwe Rauschenbach and Heidrun Schumann", volume = "23", number = "6", journal = "Computers and Graphics", } @InProceedings{EVL-1999-147, year = "1999", title = "The Rectangular Fish Eye View as an Efficient Method for the Transmission and Display of Large Images", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-147", author = "U. Rauschenbach", month = oct, booktitle = "Proceedings of IEEE ICIP'99, Kobe, Japan", } @Conference{EVL-1999-148, year = "1999", title = "A fast voxel-based 2{D}/3{D} registration algorithm using a volume rendering method based on the shear warp factorization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-148", author = "J. Weese and R. G{\"{o}}cke and G. P. Penney and P. Desmedt and T. Buzug and H. Schumann", month = feb, booktitle = "SPIE International Symposium on Medical Imaging, San Diego,USA", } @InProceedings{EVL-1999-149, year = "1999", title = "Blobworld: {A} system for region-based image indexing and retrieval", author = "Chad Carson and Megan Thomas and Serge Belongie and Joseph M. Hellerstein and Jitendra Malik", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-149", abstract = "Blobworld is a system for image retrieval based on finding coherent image regions which roughly correspond to objects. Each image is segmented into regions by fitting a mixture of Gaussians to the pixel distribution in a joint color-texture-position feature space. Each region ({"}blob{"}) is then associated with color and texture descriptors. Querying is based on the user specifying attributes of one or two regions of interest, rather than a description of the entire image. In order to make large-scale retrieval feasible, we index the blob descriptions using a tree. Because indexing in the high-dimensional feature space is computationally prohibitive, we use a lower-rank approximation to the high-dimensional distance. Experiments show good results for both querying and indexing.", month = jun, booktitle = "Third International Conference on Visual Information Systems", publisher = "Springer", } @TechReport{EVL-1999-15, year = "1999", title = "Mesh-Oriented 3{D} Graphics Architecture", author = "Tzi-cker Chiueh Tulika Mitra", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-15", abstract = "Although triangle meshes are used pervasively in 3D graphics applications and there exist highly efficient mesh representations, almost all existing 3D graphics processors are based on the assumption that individual triangles are processed completely independently of one another. Consequently, none of these graphics processors are able to exploit triangle mesh's vertex/edge sharing property. This paper describes a meshoriented 3D graphics architecture called Heresy, which treats meshes as first-class objects, and significantly reduces the computation and communication costs of rendering triangle meshes by reusing intermediate computation results and eliminating data redundancy. The central architectural feature of Heresy is a highly efficient triangle mesh representation based on breadth-first mesh traversal, which is applied throughout the entire 3D graphics pipeline, from geometric transformation, clipping, to rasterization, and thus enables aggressive exploitation of vertex/edge sharing to minimize both transformation/shading and rasterization cost. Results of a detailed simulation study based on a set of sophisticated 3D models demonstrate the superiority of Heresy over traditional triangle-based architectures and show that on the average the geometric transformation/shading cost, the communications overhead between CPU and the rasterization hardware, and the rasterization delay are reduced by 82\%, 74\% and 37\%, respectively. Moreover, owing to a window-based prefetching technique, the on-chip storage requirement for Heresy is shown to remain small (about 128 vertices wide) and largely independent of the size of the triangle mesh.", number = "TR-62", institution = "Experimental Computer Systems Lab, State University of New York Stony Brook", } @InProceedings{EVL-1999-150, pages = "377--395", year = "1999", title = "Visualisierung von Multiparameterdaten in Raum und Zeit -eine Systematisierung-", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-150", author = "Heidrun Schumann", organization = "Society for Computer Simulation International, San Diego, Erlangen", booktitle = "Proceedings {"}Simulation und Visualisierung '99{"}", } @TechReport{EVL-1999-16, year = "1999", title = "Modeling with {A}-patches from Rational Trivariate Functions", author = "Guoliang Xu and Hongci Huang and Chandrajit Bajaj", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-16", abstract = "We approximate a manifold triangulation in IR3 using smooth implicit algebraic surface patches, which we call A-patches. Here each A-patch is a real iso-contour of a trivariate rational function defined within a tetrahedron. The rational trivariate function provides increased degrees of freedom so that the number of surface patches needed for free-form shape modeling is significantly reduced compared to earlier similar approaches. Furthermore, the surface patches have quadratic precision, that is they exactly recover quadratic surfaces. We give conditions under which a C1 smooth and single sheeted surface patch is isolated from the multiple sheets.", keywords = "Algebraic surface, rational A-patch, surface fit, triangulation", institution = "Department of Computer Science, Center for Computational Visualization, University of Texas, Austin", } @TechReport{EVL-1999-17, year = "1999", title = "Active Contouring of Images with Physical {A}-splines", author = "Chandrajit L. Bajaj and Valerio Pascucci and Robert J. Holt and Arun N. Netravali", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-17", abstract = "A-splines are implicit real algebraic curves in Bernstein-B{\'e}zier (BB) form that are smooth. We use these in an algorithm for active contouring of images. One advantage of A-splines is that any change to the controlling weights only affects the curve locally, which results in fast convergence. Our active A-splines are also level sets of a time-dependent function with the added flexibility of a dynamic unstructured mesh. Other advantages include the ability to use lower degree polynomials than traditional polynomial parametric B-splines. A-splines also avoid the necessity of dealing with poles that can arise from rational parametric B-splines (NURBS), and they also allow an easy specification of orientation, so that they may be driven to converge to an interior or exterior contour. Our algorithm finds image contours by using a level-set method to obtain an initial close fitting polygon, constructing a physical A-spline contour by minimizing the image energy, and then minimizing the total energy by considering the energy in each spline segment individually.", number = "99-03", institution = "Department of Computer Science, Center for Computational Visualization, University of Texas, Austin", } @InProceedings{EVL-1999-170, pages = "68--77", year = "1999", title = "Tetrahedal Discretization of Complex Volumetric Spaces: Implementation, Efficiency, Robustness and Interactive Control", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-170", author = "Ashwini Patgawkar and Dinesh Shikhareand and Satyashree Mahapatra and S. Gopalsamy and S. P. Mudur", abstract = "The problem of tetrahedal grid generation within volumes bounded by triangled surfaces has received considerable attention in recent years due its significance in CFD analysis dealing with complex geometric bodies. Tetrahedal discretization of volume is complex, and even more so when the bounding surfaces are complex geometric configurations of intersecting doubly curved surfaces, say, represented as NURBS, as is usually the case for aircraft surfaces. In addition, the CFD analyst has to be provided with both quantitative and qualitative controls over the grid generation process in terms of the number of tetrahedal elements to be generated, their size, shape, local density, variation and so on. The implementation related issues of efficiency, robustness, scalabitlity and interactive control are thus understandably hard to handle. In this paper, we describe these issues in detail and present the solutions we have implemented in our grid generation system - VolGrid.", organization = "National Centre for Software Technology, Mumbai, India", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", } @InProceedings{EVL-1999-171, title = "Construction of Trimmed Surface Patches from Unstructured Set of Points", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "78--87", year = "1999", author = "N. Adhikary and B. Gurumoorthy", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-171", abstract = "This paper addresses the problem of constructing a smooth representation of a trimmed surface patch from a given set of unstructured point data measured on the surface patch. Unlike the bottom up approaches reported thus far, the approach described in this paper is similar to the way a trimmed surface would be constructed in a CAD system. The underlying four sided patch is first identified and constructed from the point data and then trimmed with the boundary curves to obtain the trimmed surface patch. The algorithm for identifying the underlying four sided patch is described and results of implementation on typical point data are presented.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "CAD, surface modelling, surface fitting, reverse engineering", } @InProceedings{EVL-1999-172, title = "Virtual Reality and Augmented Reality", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "88--94", year = "1999", author = "Stefan M{\"{u}}ller", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-172", abstract = "Virtual Reality (VR) became an important technology for the daily development process. One example is the use of {"}digital mock-ups{"} with the aim to reduce the number of prototypes in order to minimize product development times and costs. A far less known technology is described by the term {"}Augmented Reality{"}. As an extension of Virtual Reality, this technology integrates virtual information into a real environment. In this paper, an overview of existing solutions in both areas and the potential for future development areas are presented.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "virtual reality, augmented reality", } @InProceedings{EVL-1999-173, title = "A Virtual Environment for Interactive Music Reproduction", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "95--100", year = "1999", author = "Hartmut Chodura and Arnold Kaup", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-173", abstract = "In this paper a new application for interactive music experience is described. In contrast to the conventional way of consuming music productions, the user is able to change the location of sound sources, like instruments or vocals and navigate through a three dimensional virtual environment. Additionally, he can change the visual and acoustical presentation of the scene. So the virtual performance can take place in a church or a chamber for instance. The functionality of the system and the synchronization between the graphic and sound components is described. Also discussed are important aspects for audio-visual presentations in virtual worlds. For the proposed system a new way of recording and production is required. The multi-track recording of a chamber quartet in an anechoic chamber is specified. The feasibility for various music types is evaluated. Because of taking advantage of 3D output for graphics and sound it is highly entertaining. But also for professionals, like architects and music students there are useful applications, for example individual {"}minus-one recordings{"}.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "virtual environments, 3D HCI, spatial audio", } @InProceedings{EVL-1999-174, title = "Virtual Surgery: Methods and Areas of Application", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "101--105", year = "1999", author = "Hans-Peter Meinzer and Harald Evers and Gerald Glombitza", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-174", abstract = "This paper describes the current objectives, methods and applications of virtual surgery. The increased use of three-dimensional imaging has led to an improved diagnosis and enables one to plan surgical procedures in an individualized manner, focusing on the specific patient. Since the conventional evaluation of the large quantity of image data is a complex task, computerassisted processing has gained increased interest. In light of this, the range of methods required for applications in virtual surgery are explained in a step by step manner and are clarified by selected examples. Finally, a discussion follows of the current areas of application, the systems employed as well as the future objectives and developments. The value of systems that support surgery will continue to increase. They profit from a continual improvement in imaging as well as new analysis and presentation techniques which simplify preperative planning and will in the future do the same for the intraoperative implementation of surgical objectives.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "volume visualization, segmentation, virtual surgery", } @InProceedings{EVL-1999-175, title = "Model-Based Invariant using Simulated Motion for the Recovery of Planar Objects", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "107--116", year = "1999", author = "Hock Soon Seah and Kok Cheong Wong", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-175", abstract = "A scheme to recover 3D planar object shapes in a single perspective image is presented. The model-based invariant proposed to recognize planar objects is based on the computation of a simulated camera motion between appropriate template and the shape image. It features an active template whose position and orientation are determined for accurate computation of this simulated motion. With the motion parameters between the template and the shape image known, the surface normal of the template, and the surface normal of the object are estimated. If the observed shape is a view of the template, the recovered surface normal of the template will agree with the known value. Once the object is recognized, its pose is also recovered. The recovered 3D surface can then be used for facilitating interactions between the images and computer graphics in augmented reality applications.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "structure-from-motion, planar objects recovery, model-based invariant, active template", } @InProceedings{EVL-1999-176, title = "Evolution of Autonomous Actors in an Interactive Real-Time Environment", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "117--122", year = "1999", author = "Cedric Sanza and Christophe Destruel and Yves Duthen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-176", abstract = "This paper presents a learning system based on artificial life that uses short-term memory and knowledge sharing. Inspired from classifier systems, the model allows to generate behaviors for agents integrated in a multi-task environment. The user, immersed in the scene, interacts through this clone with autonomous actors. By his own behavior, he influences the agents' one. An agent perceives the world through sensors and acts through effectors in order to produce rules (called classifiers). Rewards from the environment allow to adjust the strength of every rule that is used in order to define the best behavior. The {"}sending message{"} protocol has been included to increase the performances of the system in complex environment. By combining communication and evolution, we then produce a real-time application (a virtual soccer) where the user plays with the other agents. After a short period of adaptation, the simulation gives some positive results: a coherent global behavior is built by the teams.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "agent, evolution, adaptation, classifier systems, virtual environments", } @InProceedings{EVL-1999-177, title = "Hierarchical Model For Complex Geometrical Objects Modeling", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "123--128", year = "1999", author = "Oskar Guilbert and Yves Bertrand", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-177", abstract = "The representation of multi-resolution geometric objects can easily overflow the resources of the most powerful computers. Indeed, going down the hierarchy, the number of elements of an object grows exponentially and it is impossible to represent it in extenso. The traditional CAD tools are generally restricted to one level of representation or one topological dimension. That is why we define a B-rep hierarchical model for geometric objects based on generalized maps, and which is homogeneous at all dimensions. It allows important information savings thanks to the cloning of objects. Clones can be linked topologically, even when they come from one representation level to another, may possibly increase the number of topological dimensions, in order to produce more various and richer objects, or degrease the number of topological dimensions in order to realize further information savings. Finally, the interactive handling of this model authorizes, throughout the creation process, operations both at a given level of the hierarchy and on the structure of the hierarchy itself.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "modeling curves / surfaces / solids / volumes, geometry compression, geometry simplification, ease-of-use for 3D designs", } @InProceedings{EVL-1999-178, title = "An algorithm for Interference Detection in Cloth Animation", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "129--133", year = "1999", author = "Torbjorn Hallgren and Chandini Wijenayake Halpegamage", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-178", abstract = "This paper presents an algorithm for low-level (also called elementary) collision detection. This encompasses accurate and efficient computation of intersection and proximity parameters. The algorithm in it's basic form addresses collisions between convex polyhedra. However, a small extension makes it attractive also for intersection and proximity computations for any application involving colliding surfaces modeled by means of polygonal meshes. The algorithm offers an improvement in time performance by a factor of about 2 or more compared to often referenced algorithms. The algorithm is generally applicable, but the particular application in mind is cloth modeling and animation. The method is based on a well established algorithm for line clipping.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "collision detection, cloth animation, virtual reality", } @InProceedings{EVL-1999-179, title = "Image-Based Rendering: {A} Survey", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "136--143", year = "1999", author = "Heinrich M{\"{u}}ller", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-179", abstract = "Image-based rendering means to use images for modeling 3D scenes from which new views can be rendered, like from traditional surface-based scene models. A well-known step in this direction was classical image-based texture mapping. Image-based rendering helps to cope with complex realistic scenes which can hardly be modeled traditionally, and to render such scenes in significant less time. We give an overview of the different approaches to image-based rendering developed in the last few years, and show up the achievements, but also difficulties not yet solved. We do this in a systematic framework. The basis of the framework is the representation of the scene in an optical ray space. From that, direct image-based rendering methods can be immediately deduced, like light field rendering, the lumigraph, and direct view interpolation. Other classes are reconstructive methods, like depth images, layered depth images, dexel and voxel volumes, and hybrid surface-/image-based modeling and rendering. This variety of methods shows the interest image-based modeling and rendering currently finds, and is an example of increasing interaction between the field of computer graphics and the field of digital image processing.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "image-based rendering, rendering", } @InCollection{EVL-1999-18, pages = "215--255", year = "1999", title = "Three-dimensional grid drawings of graphs", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-18", author = "J{\'a}nos Pach and Geza T{\'o}th and Torsten Thiele", address = "Mount Holyoke College", editor = "Bernhard Chazelle and Jacob E. Goodman and Richard Pollack", volume = "223", booktitle = "Advances in Discrete and Computational Geometry", publisher = "American Mathematical Society", } @InProceedings{EVL-1999-180, title = "Hybrid Shear-Warp Rendering", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "144--153", year = "1999", author = "M. Nordin Zakaria and Md. Yazid Md. Saman", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-180", abstract = "Shear-warp rendering is a fast and efficient method for visualizing a volume of sampled data based on a factorization of the viewing transformation into a shear and a warp. In shear-warp rendering, the volume is resampled, composited and warped to obtain the final image. Many applications, however, require a mixture of polygonal and volumetric data to be rendered together in a single image. We describe, in this paper, a new approach for extending the shear-warp rendering to simultaneously handle polygonal objects. We present a data structure, that we call the zlist-buffer, which is basically a multilayered z-buffer. With the zlist-buffer, an object-based scan conversion of polygons requires only a simple modification of the standard polygon scan-conversion algorithm. We show in this paper how the scan conversion can be integrated with shear-warp rendering of run-length encoded volume data to obtain quality images in real time. We discuss the quality and performance of the approach using a number of test renderings.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "volume rendering, polygon rendering, shear-warp factorization", } @InProceedings{EVL-1999-181, pages = "154--161", year = "1999", title = "Visible Space Models: 2 1/2-{D} Representation for Large Virtual Environments", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-181", author = "P. J. Narayanan", abstract = "Traditional geometric representation of virtual environments describe its component objects independently in a single global reference frame. This could be inefficient for large environments, neccessitating representational mechanisms like level-of-detail (LOD) and visibility culling to reduce the adverse impact of intricate detail that has little visible influence from the current viewpoint. In this paper, we present an alternate representation of virtual environments in terms of multiple viewpoint-based (i.e. 2 1/2-D) models called Visible Space Models (VSM). These are motivated by the recent efforts to compute the geometric structure of a real scene using range fining devices. We present the MVSM representation and the associated algorithms for rendering in this paper.", organization = "National Centre for Software Technology, Mumbai, India", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", } @InProceedings{EVL-1999-182, pages = "162--167", year = "1999", title = "{LDP}: An Image-based Representation for Interactive Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-182", author = "Li Xinxiao and Zheng Nanning and Jin Li", abstract = "In this paper, an efficient image-based modeling and rendering approach is presented. This method, which is an extension of layered depth image (LDI), uses a panorama-like structure to describe the model of the object or scene. The representation has the regularity of pixels' position and epipolar line relationship among multiple views. It is fitful to compress N sample images efficiently, and generate new views in interactive rate.", organization = "National Centre for Software Technology, Mumbai, India", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", } @InProceedings{EVL-1999-183, title = "Wavelets for Volume Fusion", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "168--177", year = "1999", author = "Lakshmish. M. R. and Swami Manohar and Vijay Chandru", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-183", abstract = "Volume Fusion is a technique by which two or more {"}similar{"} volumes are intermixed to yield a volume which includes the significant features present in each of the volumes. Volume fusion has direct applications in several areas including medicine and computational fluid dynamics. In this paper we describe a novel waveletbased algorithm for volume fusion that is an extension to three dimensions of an algorithm for image fusion presented by H. Li et al. in 1995. We present a simple measure for the effectiveness of volume fusion and demonstrate the quality of our algorithm with respect to this measure. A Gaussian-blur technique is used to generate the 'similar' volume data sets from a standard shell data set and these derived data sets have been used to demonstrate our algorithm.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "volume graphics, wavelets, volume fusion, visualization", } @InProceedings{EVL-1999-184, pages = "178--186", year = "1999", title = "Motion vector interpolation using wavelets", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-184", author = "S. H. Srinivasan and P. Padmashree and K. R. Ramakrishnan", abstract = "Motion vectors constitute an important feature for object segmentation algorithms. In MPEG we have motion vectors defined at the macroblock level. In order to get realistic object boundaries, we need to get the motion vectors at the pixel level. In other words, we need to interpolate the MPEG motion vectors from the block level to the pixel level. There are conflicting requirements on the interpolation scheme. (1) The interpolation scheme used should interpolate smoothly. (2) The interpolation scheme should also preserve discontinuities in order to ensure realistic segmentation. The well-known linear interpolation of motion vectors smoothes discontinuities in the motion field. The wavelet interpolation scheme (Pentland, 1994) which meets these twin objectives considered in this paper for motion vectors. This algorithm also has other good properties. (1) It regularizes the interpolation operator. (2) It runs in linear (O(n)) time. We cluster the interpolated motion vectors to object boundaries. We compare the results of object segmentation obtained using wavelet interpolation with that obtained using linear interpolation. The object boundaries obtained using wavelet interpolation are closer to real object boundaries as expected.", organization = "National Centre for Software Technology, Mumbai, India", address = "05, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", } @InProceedings{EVL-1999-185, title = "Automated Generation of Visual Elements for Image Processing Algorithms", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "187--192", year = "1999", author = "Carlos E. Cardenas S. and Athanasios M. Demiris and Hans-Peter Meinzer", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-185", abstract = "The development of a new image processing algorithm, the {"}semantic debugging{"} and its application are usually supported by a user interface. A graphical user interface makes the interactive operation and parameterization of the algorithms easier. The development of graphical user interfaces, though, is a laborious and complex process and distracts the developer of image processing solutions from his/hers actual work-tasks. In this paper we present a generic system, which offers an extensive automation of the generation process of graphical user interfaces specially designed and developed for image processing algorithms. The primary goal was to reach an automation level such as to have the system generate user interface elements with either minimal or no additional information or interference by the developer. We developed a framework for the generation of graphical user interface elements and implemented a test-editor which demonstrates the feasibility of such an approach and the practical advantages of its application in the realm of medical image processing.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "visual interface, image processing algorithms, GUI-generation, object-oriented frameworks, rapid prototyping", } @InProceedings{EVL-1999-186, title = "A New Approach to Lighting Design", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "194--203", year = "1999", author = "Antonio Cardoso Costa and Antonio Augusto Sousa and Fernando Nunes Ferreira", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-186", abstract = "There is a need for robust and reliable lighting design applications. Architects, engineers and designers need working tools to define, test and validate the lighting solutions for their problems. Unfortunately, available tools are limited and inappropriate for interactive or creative use. In this paper, we present a new approach to the lighting design problem based on two methodologies that include scene geometry, material properties and lighting design goals. It is possible to obtain luminaires characteristics that maximize the attainment of the lighting goals, which may include different kinds of constraints or objectives (lighting, geometrical, etc.). Our main goal is to shorten and improve the design cycle.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "lighting design, global illumination, light transport", } @InProceedings{EVL-1999-187, title = "Building a Visualisation on the Foundation of Software Ergonomics and Media Design", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "204--210", year = "1999", author = "Bernhard E. B{\"{u}}rdek and Maximilian Eibl and J{\"{u}}rgen Krause", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-187", abstract = "Boolean queries in information retrieval are still a problem not solved. Users have serious trouble building Boolean expressions. Although many IR systems move on to probabilistic methods, there still remain domains where Boolean algebra is needed. There have been made some attempts introducing visualisation to solve the problem but they brought a bunch of new problems with them. This paper deals with an attempt to consider aspects of software ergonomics and interface- and mediadesign in order to find a suitable visualisation.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "document retrieval, visualisation, human computer interface, software ergonomics, graphics design", } @InProceedings{EVL-1999-188, title = "Simulation of Ply Realization in Composites Manufacturing", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "211--216", year = "1999", author = "P. V. Kiran Kumar and V. Devaraja Holla and K. G. Shastry", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-188", abstract = "Laminated composite structures are generally realized using Uni.-directional tapes and bi-directional (woven) fabric. A simulation process is a must to assess the realizability of the component in terms of fiber orientation and fabric deformation. It serves as a manufacturing aid to the composite lay-up process. It also ensures process repeatability and maximizes material utilization. The present paper describes the simulation software developed for realizing the composite ply of any shape using bi-directional fabric or uni-directional tapes. Though the fabric and tape material constituents are same, the lay-up path taken by fabric and tape on the tool surface with the same initial conditions are different due to their differing mechanical properties. The uni-directional tapes are mapped onto the component surface by estimating natural path of the tape. Tchebychev net-based mapping is used for the draping simulation of a bi-directional fabric on the tool surface contour. The user can define several overlapping or non-overlapping regions on the given surface, and can run the simulation on individual regions separately, which facilitates handling of complex surfaces.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "ply, bi-directional fabric, uni-directional tape, surface allocation, draping", } @InProceedings{EVL-1999-189, title = "Automatic Reconstruction of Shape, Surface and Solid Model of Laminated Composites", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "217--222", year = "1999", author = "V. T. Johnson and Prabba Srinivasan and G. V. V. Ravi kumar and K. G. Shastry", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-189", abstract = "With the advent of powerful graphics computers, Computer Aided concurrent engineering design of geometrically complex objects is becoming increasingly popular in the realm of design and manufacture of laminated composites (laminate). The precise definition of geometric data of the laminate and plies in various forms such as tessellated model, surface model and solid model are required for design and manufacture of the laminate. This geometric data for a laminate is to be computed from the geometry of the layup surface, the ply boundary curves and ply thickness information. This paper attempts to address these issues and presents methodologies to retrieve and reconstruct precise representation of the laminate in the form of tessellated surface model, G1 continuous multiple-patch surface model. Further research effort has evolved a software system for automating the same on UNIX platform using C/C++.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "laminated composites, geometrically constrained triangulation, surface reconstruction, solid model", } @TechReport{EVL-1999-19, year = "1999", title = "Applying an Edit Distance to the Matching of Tree Ring Sequences in Dendrochronology", author = "Carola Wenk", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-19", abstract = "In dendrochronology wood samples are dated according to the tree rings they contain. The dating process is a one dimensional matching in which the sequence of tree ring widths in the sample is compared to a dated master sequence. Assuming that a tree forms one ring per year a consecutive piece in the master sequence is searched which has the same length than and is similar to the sample sequence. A brute force algorithm takes $\theta(mn)$ time where n and m are the lengths of the sample and the master sequences, respectively. Yet, sometimes a tree produces no ring or even two rings in a year. A sample sequence containing this kind of inconsistencies cannot be dated correctly by the simple dating algorithm mentioned above. We therefore introduce a $O(\alpha^{4}(m+n)+\alpha^{2}mn)$ algorithm for dating such sample sequence against an error-free master sequence. Our algorithms takes into account that the sample might contain up to $\alpha$ missing our double rings and suggests possible positions for these kind of inconsistencies. This is done by employing an edit distance as the distance measure.", month = jan, institution = "Freie Universit{\"a}t Berlin, Department of Computer Science, Germany", } @InProceedings{EVL-1999-190, title = "A Virtual Prototyping, Simulation And Automated Control System For {A} Family of Palletising Robots", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "223--228", year = "1999", author = "Juha Tuominen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-190", abstract = "The main interest within the robotics research has recently been in the highly articulated manipulators and the related computationally complex problems, such a automated path planning. At the same time, the increased demand for flexibility, effectivity and safety in the portal robot and palletising applications has brought new challenges to the domain. The design and implementation of a modern palletising robot system targeted at applications dealing with the handling of a large variety of products and orders requires the use of the same technique as with the case of any other type of a robot cell. With the increased demands, also Virtual prototyping, simulation and off-line programming have a lot to offer to the palletising robot applications. This paper reports the design and implementation of an integrated software system for virtual prototyping, simulation and automated control of a family of palletising robots.", organization = "ational Centre for Software Technology, Mumbai, India", keywords = "robotics, virtual prototyping, off-line programming, palletising, graphical simulation, 3D modeling, reconfigurable control system", } @InProceedings{EVL-1999-191, title = "Applying {A}. {I}. Informed Search and Iterative Methods to Solve Containment Problems for the Footwear Industry", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "229--234", year = "1999", author = "Nuno Marques and Joao Bernardo and Pedro Capela", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-191", abstract = "This paper deals with containment problems in which there is a set of shapes to be allocated in another shape, called the container. We are making the correspondence between 2D translational or rotational containment problems and generic A* informed search methods for geometric reasoning. A* can be proven to be complete and optimal if the heuristic has some restrictions, that is, if it holds the admissibility property. We formally present the 2D containment problems as an A* informed search problem and give an admissible heuristic, using Minkowski operators. We also present an iterative containment algorithm that selects a shape from a set of shapes to place at each step to keep running times controlled. We mix both approximations in order to get results that have low time execution and still can compete with the manual containment process.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "containment algorithms, heuristic search, Minkowski operators", } @InProceedings{EVL-1999-192, title = "{CAPP}: {A} 2{D} Feature Based Modeling Approach", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "235--238", year = "1999", author = "Milind D. Sinkar", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-192", abstract = "Down stream applications such as process planning, require geometric information as well as process parameters. This information is captured from the 2d-Feature Based Component Data Model (2d-FBCDM), obtained through a 2d-Feature Based Modeling System (2d-FBMS). 2d-fbms works as an integrated software module of the present 2d-CAD Systems. 2d-FBCDM can be used to take process planning decisions to generate process plan autmatically. Efforts are being made to develop a process planning system that will use the 2d-FBCDM as one of the inputs. At present, this study is confined to rotational parts only.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "2d-CAD Systems, 2d-FBMS, 2d-FBCDM, CAPP, Expert-System, Knowledge Base, Frames, Rules", } @InProceedings{EVL-1999-193, title = "Implementation of {LAN}-based Virtual Classroom and Video Telephony Services", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "240--246", year = "1999", author = "Shailendra Sinha and Anamitra Makur", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-193", abstract = "This work describes an implementation of the multimedia services involving continuous media over PCs connected by an ethernet LAN. The services we have implemented are Virtual Classroom and Video Telephony. In a Virtual Classroom scenario, there is one teacher (sender) and many students (recipients), located at different places. Video telephony is similar to conventional telephony between two parties, except that in addition to audio, video too is transmitted and received by both sides. In this work, we describe Conditional Replenishment with Forced Update as our compression algorithm for Virtual Classroom, and simple Conditional Replenishment for Video Telephony. We also describe multiplexing and demultiplexing of audio/video streams, simulated random packet loss in Virtual Classroom scenario, experiments with various packet sizes and their effect on the performance. Other relevant design issues have also been described.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "computer assisted Virtual Classroom, Video Encoding/Compression, Multimedia", } @InProceedings{EVL-1999-194, title = "Virtual Reality Semiconductor Laboratory ({VRSEMLAB}): an Advanced Training Tool for Teaching Complex Ideas", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "247--255", year = "1999", author = "Christopher Allport and Brandon Schreiner and Paul Sines and Biswajit Das", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-194", abstract = "Virtual Reality (VR) training systems are advanced interactive self-paced learning systems that are customizable and adaptable to the need of different individuals. Because of their many advantages, VR training systems are finding increased applications in a variety of disciplines. Virtual Reality's superior 3D immersive environment makes it especially suitable for teaching complex ideas, in particular, principles that involve spatial relationships. VR provides the user with the ability to visualize and manipulate objects in 3 dimensions. This results in a clearer elicitation of spatial relationships. As a demonstration of VR's potential for teaching complex themes, we have developed the Virtual Reality Semiconductor Laboratory (VRSEMLAB). It is designed to aid in teaching semiconductor device physics to undergraduate college students. VRSEMLAB demonstrates an effective method for modeling abstract and complicated 3D systems. It does so by presenting semiconductor devices in an experimental environment free of concerns of electrical safety, equipment limitations, and device limitations.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "Virtual Reality, 3D visualization, Education and Training", } @InProceedings{EVL-1999-195, title = "Authoring Courseware for Distributed Environments", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "256--263", year = "1999", author = "Jose Carlos Teixeira and Cesar Paris and Joao M. Brisson Lopes and Ana Maria Paiva", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-195", abstract = "This paper introduces a new approach to the design and delivery of computer based courseware. The new approach is based on modularity and adaptability. It allows lower courseware production costs and leads to solutions in oder to meet the new demands of the learning/teaching process such as: the inclusion of new educational technologies, the new emerging learning scenarios and, as a consequence, a whole new learning philosophy. In a global way, the concepts presented supported Individual, Group Learning and Lecturing scenarios, with or without Tutoring Support. In all these scenarios, coursware can record student performance, and even, adapt itself to student understanding and mastering of the content. This feature is of crucial interest for heterogeneous audiences. This new approach allows the creation of Virtual Learning Spaces, where learning material is distributed over the different databases, which constitute the system. This way all the learning material is available at all places as if it was stored in one. IDEALS, a European Union funded project, implemented these concepts and used the transport mechanism of the World Wide Web to present learning material and interact with learners. The use of such technology ensures future evolution of the application and simplifies the authoring process.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "authoring tools and methodologies, Internet based educational systems, cost effectiveness, on-demand education", } @InProceedings{EVL-1999-196, title = "Spherical harmonic surface modeling with improved center location", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "265--273", year = "1999", author = "Sarp Ert{\"{u}}rk and Tim J. Dennis", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-196", abstract = "Spherical harmonic (SH) modeling is used in the representation of rigid and non-rigid object shapes. The object surface is expressed in the form of a radial distance from a chosen center and two spatial angle co-ordinates. A linear combination of SH basis functions are used for the radial distance, with coefficients computed from range data sampled on the object surface. This paper focuses on the selection of an appropriate center location to improve the fit between actual shape and the SH model. Instead of pre-determined positions the co-ordinate system center is chosen to be located close to areas of high detail. This is accomplished by comparing the surface with its low order SH approximation using a variance-based technique. The technique provides a direction with respect to current co-ordinate system along which the center is located. This paper demonstrates that it is possible to improve visual and statistical accuray of SH representation for objects with concentrated local detail, by improving the location of the co-ordinate system center.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "shape representation, surface modeling, spherical harmonics", } @InProceedings{EVL-1999-197, title = "Implicit Surface Approximation Using Adaptive Spatial Meshes", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "ntasey Typesetters Pvt. Ltd.", pages = "274--280", year = "1999", author = "Heinrich M{\"{u}}ller and Michael Wehle", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-197", abstract = "An algorithm is presented which calculates surface meshes approximating an implicitly defined surface. The algorithm first performs an adaptive spatial tetrahedrization from which the surface is extracted by an marching tetrahedra approach. Our improvement over the known implementations of this approach is the context-free calculation of the spatial tetrahedrization which is more efficient than existing context-sensitive or two-pass solutions. Furthermore, an improved quality of the surface mesh is achieved by setting the subdivision points on the surface so that the resulting surface mesh is part of the resulting spatial mesh.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "graphics and geometric algorithms, modeling surfaces", } @InProceedings{EVL-1999-198, title = "Engineering a geometric Approach for Efficient Visible Surface Determination", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "281--288", year = "1999", author = "Amit Shirsat and Gopat Shevare", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-198", abstract = "We describe a simple, robust and efficient algorithm to compose the trapezoidal decomposition of line segments by endpoint rounding and exact computation of the signs of determinants. We use a two pass approach derived from [3] to delay the computation of intersection to the second pass. Using this approach and Mulmuley's [6] randomized incremental construction, we give an algorithm for an efficient geometric solution to visible surface determination.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "computational geometry, robustness, exact computation, hidden surface removal (HSR), trapezoidal decompositions.", } @InProceedings{EVL-1999-199, title = "Modelling of the Left Ventricle with a Dynamic Gaussian Blob Model", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", pages = "289--293", year = "1999", author = "Soo-Mi Choi and Myoung-Hee Kim", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-199", abstract = "We present a method for modelling of the heart's left ventricle (LV) wall motion during a cardiac cycle. In this method, the LV is approximated by a dynamic gaussian blob model, which unify a gaussian interpolation basis FEM element with a superellipsoid. The proposed model describes the shape of the LV and the wall motion using a physics-based approach. It tracks the LV due to forces exerted from 3-D points corresponding to the wall of the LV in a time sequence of images. We believe that our method may help automatic diagnosis of heart diseases.", organization = "National Centre for Software Technology, Mumbai, India", keywords = "left ventricle, finite element method, gaussian interpolations, superellipsoids", } @Article{EVL-1999-2, pages = "87--115", year = "1999", title = "Deformable Smooth Surface Design", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-2", author = "H. Edelsbrunner", language = "en", abstract = "A new paradigm for designing smooth surfaces is described. A finite set of points with weights specifies a closed surface in space referred to as skin. It consists of one or more components, each tangent continuous and free of self-intersections and intersections with other components. The skin varies continuously with the weights and locations of the points, and the variation includes the possibility of a topology change facilitated by the violation of tangent continuity at a single point in space and time. Applications of the skin to molecular modeling and to geometric deformation are discussed.", month = jan, volume = "21", number = "1", journal = "Discrete and Computational Geometry", } @TechReport{EVL-1999-20, year = "1999", title = "Introduction to Integer-Coordinate Crystalline Meshes", author = "Vasiliki Chatzi and Franco P. Preparata", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-20", abstract = "We introduce 2D and 3D integer-coordinate crystalline meshes and discuss their properties. We explain that crystalline meshes give us both the flexibility of variable element density in different parts of the domain as well as the ability to construct the system of equations quickly and accurately, which makes them ideal for problems where the domain has regions of interest. We also illustrate the versatility of crystalline meshes in the context of dynamic mesh adaptation, discussing in detail the refinement procedure. Finally, we give some experimental results and compare the computational behavior of crystalline meshes with that of current methods.", month = feb, number = "CS-99-01", institution = "Brown University", } @InProceedings{EVL-1999-200, pages = "295--302", year = "1999", title = "ScanlineFlow Rasterization - {A} Sort-Last Algorithm for Polygon Rendering on a Multicomputer", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-200", author = "Joao Madeiras Pereira and Mario R. Gomes", abstract = "A sort-last strategy for polygon parallel rendering, namely the ScanlineFlow Rasterization algorithm, is described. Its main characteristic resides on the fact that both steps, rendering and merging, run concurrently. By taking advantage of a pipeline interconnection network and since this algorithm renders an image one scanline at a time, each node rasterizes multiple polygons active on a given scanline after synchronisation with the previous node in order to read the rasterization data concerning that scanline. The execution is pipelined, in the sense that while a node is rasterizing a scanline (already rasterized) to the next node. The algorithm makes use of the full-frame merging technique because merging a full frame from each node is very regular and easy to implement. This solution has provided good results and is a viable alternative to implement sort-last algorithms on a multicomputer. Our developing platform consisted of a Parsytec MultiCluster machine with seventeen processors running the Helios Operating System and using the CDL (Component Distributing Language) parallel programming language.", organization = "National Centre for Software Technology, Mumbai, India", address = "305, Mahadkar Chambers, 127/3A, Karve Road, Kothrud, Pune 29", editor = "S. P. Mudur and Dinesh Shikhare", booktitle = "ICVC99 - International Conference on Visual Computing", publisher = "Fontasey Typesetters Pvt. Ltd.", } @Article{EVL-1999-201, pages = "20--21", year = "1999", title = "Visual Data Mining", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-201", author = "Pak Chung Wong", month = sep, note = "guest editor's introduction", keywords = "state of the art, data mining, visualization, techniques", volume = "19", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-202, pages = "61--65", year = "1999", title = "Visualizing Underwater Environments Using Multifrequency Sonar", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-202", author = "Paul Chapman and Derek Wills and Graham Brookes and Peter Stevens", abstract = "This article introduces seabed visualization by describing three case studies that use a high-speed, multifrequency, continuous scan sonar called the Seabed Visualization System.", month = sep, volume = "19", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-203, pages = "22--31", year = "1999", title = "{HD}-Eye: Visual Mining of High-Dimensional Data", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-203", author = "Alexander Hinnenburg and Daniel A. Keim and Markus Wawryniuk", abstract = "An advanced clustering algorithm combined with new visualization methods interactively clusters data. Experiments show these techniques improve the data mining process.", month = sep, volume = "19", keywords = "data mining, information visualization", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-204, pages = "32--39", year = "1999", title = "Discovery Visualization Using Fast Clustering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-204", author = "William Ribarsky and Jochen Katz and Frank Jiang and Aubrey Holland", abstract = "Discovery visualization combines automated response and user selection to achieve and sustain animated action while users explore time-dependent data.", month = sep, volume = "19", keywords = "data mining, information visualization, feature-based hierarchy", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-205, pages = "40--46", year = "1999", title = "A Shape-based Visual Interface for Text Retrieval", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-205", author = "Randall M. Rohrer and John L. Silbert and David S. Ebert", abstract = "Our shape-based visual interface uses procedurally generated shapes coupled with an underlying text-retrieval engine. The interface lets users visualize multidimensional relationships among documents. We use implicit surface models for visualizing the query results of a text retrieval engine.", month = sep, keywords = "data mining, information retrieval, document retrieval, information visualization, text retrieval, procedural shapes", volume = "19", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-206, pages = "54--60", year = "1999", title = "Visualizing the Atomic Nucleus", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-206", author = "Norman D. Cook and Takefumi Hayashi and Nobuaki Yoshida", abstract = "Developments in computer science and nuclear theory make it possible to visualize the nucleus consistently among the diverse models of nuclear structure. Nuclear Visualization Software facilitates this goal.", month = sep, volume = "19", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-207, pages = "66--71", year = "1999", title = "First-Generation {ASCI} Production Visualization Environment", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-207", author = "Philip D. Heermann", abstract = "Visualization terascale computing results requires considering the entire data visualization system. The systems approach presented here decreases the time needed to prepare large data sets for visualization four-fold.", month = sep, volume = "19", keywords = "parallel computing, physics calculations, simulation", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-208, pages = "72--77", year = "1999", title = "Task-Specific Visualization Design", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-208", author = "Lloyd A. Treinish", abstract = "This case study in operational weather forecasting demonstrates the principles of task-specific visualization design: defining user needs, implementing that definition, and establishing techniques for different user goals.", month = sep, volume = "19", keywords = "3D visualization, meteorology", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-209, pages = "48--49", year = "1999", title = "Visualizing Case Studies: Drawing a Roadmap for Future Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-209", author = "Kwan-Liu Ma and Frits H. Post", month = sep, note = "Guest editor's Introduction", volume = "19", number = "5", journal = "IEEE Computer Graphics and Applications", } @InProceedings{EVL-1999-21, year = "1999", title = "A Mobile Augmented Reality User Interface for Terrestrial Navigation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-21", author = "W. Piekarski and D. Hepworth and V. Demczuk and B. Thomas and B. Gunther", month = jan, address = "Auckland, New Zealand", booktitle = "Proceedings of the Twenty Second Australasian Computer Science Conference", } @Article{EVL-1999-210, pages = "50--53", year = "1999", title = "Visualizing 3{D} Configuration Spaces for Mechanical Design", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-210", author = "Elisha Sacks and Charles Pisula and Leo Joskowicz", abstract = "We describe configuration space visualization methods for mechanical design. The research challenge is to relate the configuration space geometry to the mechanical function of the parts.", month = sep, volume = "19", keywords = "visualization, construction, robot motion, mechanics", number = "5", journal = "IEEE Computer Graphics and Applications", } @Article{EVL-1999-211, pages = "286--297", year = "1999", title = "Segmentation of gated Tl-{SPECT} images and computation of ejection fraction: {A} different approach", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-211", author = "P. Brigger and S. L. Bacharach and G. Srinivasan and K. A. Nour and J. A. Carson and V. Dilsizian and A. Aldroubi and M. Unser", abstract = "We describe a set of image processing algorithms and mathematical models that can be advantageously used in schemes for the segmentation of thallium-201-single photon emission computed tomography (SPECT) images and for computation of left ventricular ejection fraction (EF). Methods: The system consists of two independent blocs for image segmentation and computation of function. The former is based on a multiresolution elliptical coordinate transformation and dynamic contour tracking. Computation of EF is formulated on the basis of both the endocardial and epicardial contours, and we compare this formulation with that using only the endocardial border for images with low signal-to-noise ratios. The accuracy of border detection was validated against manual border tracing on FDG-PET images, simulated Tl-201-SPECT images where the true underlying borders were known, and actual Tl-201-SPECT images. Finally, we compared EFs computed for FDG-PET, technetium-99m-SPECT and Tl-201-SPECT with those obtained from planar gated blood pool imaging. Results: The automatically obtained results always were within the manual uncertainty range. Agreement between myocardial volumes from positron emission tomography and automatically obtained values from the simulated Tl-201-SPECT images was excellent (r = 0.95, n = 32), agreement between EFs from planar gated blood pool imaging and the other image modalities was good (FDG-PET: y = 5.89 + 1.21x, r = 0.92, see = 6.24, n = 19, Tc-99m-SPECT: y = -3.86 + 1.06x, r = 0.88, see = 7.78, n = 9, Tl-201-SPECT: y = 17.8 + 0.81x, r = 0.77, see = 7.44, n = 26), for noisy input data the combined use of information from epicardial and endocardial contours gives more accurate EF values than the traditional formula on the basis of the endocardial contour only. Conclusions: Alternate approaches for segmentation and computation of function have been presented and validated. They might also be advantageously incorporated into other existing techniques.", month = may, volume = "6", number = "3", journal = "J. Nuclear Cardiology", } @TechReport{EVL-1999-212, year = "1999", title = "Computing Contour Trees in All Dimensions", author = "Hamish Carr and Jack Snoeyink and Ulrike Axen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-212", abstract = "We show that contour trees can be computed in all dimensions by a simple algorithm that merges two trees. Our algorithm extends, simplifies, and improves work of Tarasov and Vyalyi and of van Kreveld et al.", month = aug, number = "TR-99-09", institution = "Department of Computer Science, University of British Comlumbia", } @TechReport{EVL-1999-213, year = "1999", title = "Practical Point-in-Polygon Tests Using {CSG} Representations of Polygons", author = "Robert J. Walker and Jack Snoeyink", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-213", abstract = "We investigate the use of a constructive solid geometry (CSG) representation of polygons in testing if points fall within them; this representation consists of a tree whose nodes are either Boolean operators or edges. By preprocessing the polygons, we seek (1) to construct a space-conserving data structure that supports point-in-polygon tests, (2) to prune as many edges as possible while maintaining the semantics of our tree, and (3) to obtain a tight inner loop to make testing the remaining edges as fast as possible. We utilize opportunities to optimize the pruning by permuting sibling nodes. We find that this process is less memory-intensive than the grid method and faster than existing one-shot methods.", month = nov, number = "TR-99-12", institution = "Department of Computer Science, University of British Comlumbia", } @Article{EVL-1999-214, pages = "52--58", year = "1999", title = "Solving Einstein's Equation on Supercomputers", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-214", author = "Gabrielle Allen and Tom Goodale and Gerd Lanfermann and Edward Seidel and Werner Benger and Hans-Christian Hege and Andre Merzky and Joan Masso and John Shalf", abstract = "Globally distributed scientific teams, linked to the most powerful supercomputers, are running visual simulations of Einstein's equations on the gravitational effects of colliding black holes.", month = dec, keywords = "scientific visualization, visualization software, theory of relativity, collaborative visualization", volume = "32", number = "12", journal = "IEEE Computer", } @Article{EVL-1999-215, pages = "36--43", year = "1999", title = "Distance Visualization: Data Exploration on the Grid", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-215", author = "Ian Foster and Joseph Insley and Gregor von Laszewski and Carl Kesselman and Marcus Thiebaux", abstract = "We describe an online system that supports three-dimensional tomographic image reconstruction -- and subsequent collaborative analysis -- of data from remote scientific instruments.", month = dec, volume = "32", number = "12", journal = "IEEE Computer", } @Article{EVL-1999-216, pages = "44--51", year = "1999", title = "Virtue: Performance Visualization of Parallel and Distributed Applications", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-216", author = "Eric Shaffer and Daniel A. Reed and Shannon Whitmore and Benjamin Schaeffer", month = dec, volume = "32", number = "12", journal = "IEEE Computer", } @Article{EVL-1999-217, pages = "59--65", year = "1999", title = "Interactive Simulation and Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-217", author = "C. Johnson and S. G. Parker and C. Hansen and G. L. Kindlmann and Y. Livnat", abstract = "As computational science and engineering applications grow in complexity, working with the data becomes increasingly difficult. An emerging technology - called computational steering - addressses this problem by providing a mechanism to integrate modeling, simulation, data analysis, and visualization.", month = dec, volume = "32", number = "12", journal = "IEEE Computer", } @Article{EVL-1999-218, pages = "66--73", year = "1999", title = "Visualization in Teleimmersive Environments", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-218", author = "Jason Leigh and Andrew E. Johnson and Maxime Brown and Daniel J. Sandin and Thomas A. DeFanti", abstract = "In teleimmersion, collaborators at remote sites share the details of a virtual world that can autonomously control computation, query databases, and gather results. They don't meet in a room to discuss a car engine. They meet in the engine itself.", month = dec, keywords = "visualization, virtual environments, collaborative virtual reality", volume = "32", number = "12", journal = "IEEE Computer", } @Conference{EVL-1999-219, year = "1999", title = "Fersteuerung und Fernüberwachung von verteilten Anwendungen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-219", author = "André Merzky", note = "in press", booktitle = "Conference Booklet HLRN-Workshop: Wissenschaftliche Anwendungen auf Höchstleistungsrechnern", } @Article{EVL-1999-22, pages = "177--181", year = "1999", title = "Isoperimetric Inequalities for Densities of Lattice-Periodic Sets", author = "Peter Brass", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-22", note = "appeared also as preprint Freie Universit{\"a}t Berlin, Fachbereich Mathematik und Informatik Serie B 97-05", volume = "127", journal = "Monatshefte f{\"u}r Mathematik", } @Article{EVL-1999-220, pages = "93--96", year = "1999", title = "A quantitative three-dimensional model of the Drosophila optic lobes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-220", author = "Karlheinz Rein and Malte Z{\"o}ckler and Martin Heisenberg", volume = "9", number = "2", journal = "Current Biology", } @Conference{EVL-1999-221, pages = "942--946", year = "1999", title = "Optimized Arrangement of Osseointegrated Implants: {A} Surgical Planning System for the Fixation of Facial Prostheses", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-221", author = "Stefan Zachow and Tim C. Lueth and Detlev Stalling and Andreas Hein and Martin Klein and Horst Menneking", editor = "Lenke and Vannier and Inamura and Farman", booktitle = "Computer Assisted Radiology and Surgery (CARS'99)", publisher = "Elsevier Science B.V.", } @InCollection{EVL-1999-222, pages = "203--207", year = "1999", title = "Mehrschichtige Oberfl{\"a}chenmodelle zur computergenerierten Planung in der Chirugie", author = "Detlev Stalling and Martin Seeba{\ss} and Stefan Zachow", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-222", abstract = "Polygonale Sch{\"{a}}delmodelle bilden ein wichtiges Hilfsmittel f{\"{u}}r computergest{\"{u}}tzte Planungen im Bereich der plastischen Chirurgie. Wir beschreiben, wie derartige Modelle automatisch aus hochaufgel{\"{o}}sten CT-Datens{\"{a}}tzen erzeugt werden k{\"{o}}nnen. Durch einen lokal steuerbaren Simplifizierungsalgorithmus werden die Modelle so weit vereinfacht, da{\ss{}} auch auf kleineren Graphikcomputern interaktives Arbeiten m{\"{o}}glich wird. Die Verwendung eines speziellen Transparenzmodells erm{\"{o}}glicht den ungehinderten Blick auf die bei der Planung relevanten Knochenstrukturen und l{\"{a}}{\ss{}}t den Benutzer zugleich die Kopfumrisse des Patienten erkennen.", editor = "H. Evers and G. Glombitza and T. Lehmann and H.-P. Meinzer", keywords = "Isofl{\"{a}}chen, Simplifizierung, Transparenzen", booktitle = "Bildverarbeitung f{\"u}r die Medizin 1999", publisher = "Springer-Verlag", } @TechReport{EVL-1999-223, year = "1999", title = "Visualizing Quantum Mechanical Phenomena", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-223", author = "J. Schmidt-Ehrenberg and H.-C. Hege", abstract = "In this paper we discuss several ways to visualize stationary and non-stationary quantum mechanical systems. We demonstrate an approach for the quantitative interpretation of probability density isovalues which yields a reasonable correlation between isosurfaces for different timesteps. As an intuitive quantity for visualizing the momentum of a quantum system we propose the probability flow density which can be treated by vector field visualization techniques. Finally, we discuss the visualization of non-stationary systems by a sequence of single timestep images.", keywords = "quantum dynamics, isosurfaces, probability flow, animation", institution = "Konrad-Zuse-Zentrum f{\"ur} Informationstechnik (ZIB), Preprint SC 99-39", } @InCollection{EVL-1999-224, pages = "1049", year = "1999", title = "A 2{D} Planning System for Robot-Assisted Interventions", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-224", author = "A. Hein and T. C. Lueth and S. Zachow and M. Stien", editor = "H. U. Lemke et al.", booktitle = "Computer Assisted Radiology and Surgery", publisher = "Elsevier Science B.V.", } @InProceedings{EVL-1999-225, year = "1999", title = "Visualization of groundwater flow using line integral convolution", author = "J{\"o}rg Gotthardt and Carola Bl{\"o}mer and Detlev Stalling", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-225", abstract = "Line integral convolution (LIC) is a particularly elegant and powerful method for the visualisation of 2D and 3D vector field data. The method is based on convolving a random input texture or noise image along the streamlines of a stationary flow. The resulting output image clearly reveals the directional structure of the flow at high spatial resolution. For an efficient computing of L IC images the pixel coherence along the stream should be exploited. A fast LIC algorithm based on this principle has been d eveloped at Konrad-Zuse-Zentrum. Additional scalar quantities may be visualized using pseudo-coloring. The algorithm has been integra ted into the software system SPRING designed for the simulation of groundwater flow and transport models.", booktitle = "Proc. ModelCare'99", } @InProceedings{EVL-1000-1, pages = "73--80", year = "1999", title = "Efficient Compression of Non-Manifold Polygonal Meshes", author = "Andr{\'{e}} P. Gu{\'{e}}ziec and Frank Bossen and Gabriel Taubin and Cl{\'{a}}udio T. Silva", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-226", abstract = "We present a method for compressing non-manifold polygonal meshes, i.e. polygonal meshes with singularities, which occur very frequently in the real-world. Most efficient polygonal compression methods currently available are restricted to a manifold mesh: they require a conversion process, and fail to retrieve the original model connectivity after decompression. The present method works by converting the original model to a manifold model, encoding the manifold model using an existing mesh compression technique, and clustering, or stitching together during the decompression process vertices that were duplicated earlier to faithfully recover the original connectivity. This paper focuses on efficiently encoding and decoding the stitching information. By separating connectivity from geometry and properties, the method avoids encoding vertices (and properties bound to vertices) multiple times; thus a reduction of the size of the bit-stream of about 10% is obtained compared with encoding the model as a manifold.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Polygonal Mesh, Geometry Compression, Non-Manifold, Stitching Copyright", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-227, title = "Physically Based Motion Transformation", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "11--20", year = "1999", author = "Zoran Popovic and Andy Witkin", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-227", abstract = "We introduce a novel algorithm for transforming character anima-tion sequences that preserves essential physical properties of the motion. By using the spacetime constraints dynamics formulationour algorithm maintains realism of the original motion sequence without sacrificing full user control of the editing process. In contrast to most physically based animation techniques thatsynthesize motion from scratch, we take the approach of motion transformation as the underlying paradigm for generating computeranimations. In doing so, we combine the expressive richness of an input animation sequence with the controllability of spacetime op-timization to create a wide range of realistic character animations. The spacetime dynamics formulation also allows editing of intu-itive, high-level motion concepts such as the time and placement of footprints, length and mass of various extremities, number of bodyjoints and gravity.", organization = "Computer Graphics (SIGGRAPH) 1999", keywords = "Human Body Simulation, Physically Based Animation, Animation with Constraints", } @InProceedings{EVL-1999-228, title = "Voice Puppetry", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "21--28", year = "1999", author = "Matthew Brand", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-228", abstract = "We introduce a method for predicting a control signal from anotherrelated signal, and apply it to voice puppetry: Generating full facial animation from expressive information in an audio track. Thevoice puppet learns a facial control model from computer vision of real facial behavior, automatically incorporating vocal and facialdynamics such as co-articulation. Animation is produced by using audio to drive the model, which induces a probability distributionover the manifold of possible facial motions. We present a lineartime closed-form solution for the most probable trajectory overthis manifold. The output is a series of facial control parameters, suitable for driving many different kinds of animation ranging fromvideo-realistic image warps to 3D cartoon characters.", organization = "ACM Siggraph", keywords = "Facial animation, lip-syncing, control, learning,computer vision and audition.", } @InProceedings{EVL-1999-229, title = "Cognitive Modeling: Knowledge, Reasoning and Planning for Intelligent Characters", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "29--38", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-229", author = "John Funge and Xiaoyuan Tu and Demetri Terzopoulos", abstract = "Recent work in behavioral animation has taken impressive steps toward autonomous, self-animating characters for use in production animation and interactive games. It remains difficult, however, to direct autonomous characters to perform specific tasks. This paper addresses the challenge by introducing cognitive modeling. Cognitive models go beyond behavioral models in that they govern what a character knows, how that knowledge is acquired, and how it can be used to plan actions. To help build cognitive models, we develop the cognitive modeling language CML. Using CML, we can imbue a character with domain knowledge, elegantly specified in terms of actions, their preconditions and their effects, and then direct the characters behavior in terms of goals. Our approach allows behaviors to be specified more naturally and intuitively, more succinctly and at a much higher level of abstraction than would otherwise be possible. With cognitively empowered characters, the animator need only specify a behavior outline or {"}sketch plan{"} and, through reasoning, the character will automatically work out a detailed sequence of actions satisfying the specification. We exploit interval methods to integrate sensing into our underlying theoretical framework, thus enabling our autonomous characters to generate action plans even in highly complex, dynamic virtual worlds. We demonstrate cognitive modeling applications in advanced character animation and automated cinematography.", organization = "ACM Siggraph", keywords = "Computer Animation, Character Animation, Intelligent Characters, Behavioral Animation, Cognitive Modeling, Knowledge, Sensing, Action, Reasoning, Planning", } @TechReport{EVL-1999-23, year = "1999", title = "On the number of maximum-area triangles in a planar pointset", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-23", author = "Peter Brass and Konrad Swanepoel", note = "eingereicht bei {Discrete Comput. Geom.\/}", number = "B 99-07", institution = "Freie Universit{\"a}t Berlin, Fachbereich Mathematik und Informatik", } @InProceedings{EVL-1999-230, title = "A Hierarchical Approach to Interactive Motion Editing for Human-LikeFigures", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceddings", publisher = "Addison Wesley Longman", pages = "39--48", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-230", author = "Jehee Lee and Sung Yong Shin", abstract = "This paper presents a technique for adapting existing motion of a human-like character to have the desired features that are specified by a set of constraints. This problem can be typically formulated as a spacetime constraint problem. Our approach combines a hierarchical curve fitting technique with a new inverse kinematics solver. Using the kinematics solver, we can adjust the configuration of an articulated figure to meet the constraints in each frame. Through the fitting technique, the motion displacement of every joint at each constrained frame is interpolated and thus smoothly propagated to frames. We are able to adaptively add motion details to satisfy the constraints within a specified tolerance by adopting a multilevel B-spline representation which also provides a speedup for the interpolation. The performance of our system is further enhanced by the new inverse kinematics solver. We present a closed-form solution to compute the joint angles of a limb linkage. This analytical method greatly reduces the burden of a numerical optimization to find the solutions for full degrees of freedom of a human-like articulated figure. We demonstrate that the technique can be used for re-targetting a motion to compensate for geometric variations caused by both characters and environments. Furthermore, we can also use this technique for directly manipulating a motion clip through a graphical interface.", organization = "ACM Siggraph", keywords = "Motion Editing, Motion Adaptation, Spacetime Constraints, Hierarchical Techniques, Inverse Kinematics", } @InProceedings{EVL-1999-232, title = "Robust Mesh Watermarking", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "49--56", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-232", author = "Emil Praun and Hugues Hoppe and Adam Finkelstein", abstract = "We describe a robust method for watermarking triangle meshes. Watermarking provides a mechanism for copyright protection of digital media by embedding information identifying the owner in the data. The bulk of the research on digital watermarks has focused on media such as images, video, audio, and text. Robust watermarks must be able to survive a variety of {"}attacks,{"} including resizing, cropping, and filtering. For resilience to such attacks, recent watermarking schemes employ a {"}spread-spectrum{"} approach - they transform the document to the frequency domain and perturb the coefficients of the perceptually most significant basis functions. We extend this spread-spectrum approach to work for the robust watermarking of arbitrary triangle meshes. Generalizing spread spectrum techniques to surfaces presents two major challenges. First, arbitrary surfaces lack a natural parametrization for frequency-based decomposition. Our solution is to construct a set of scalar basis function over the mesh vertices using multiresolution analysis. The watermark perturbs vertices along the direction of the surface normal, weighted by the basis functions. The second challenge is that simplification and other attacks may modify the connectivity of the mesh. We use an optimization technique to resample an attacked mesh using the original mesh connectivity. Results show that our watermarks are resistant to common mesh operations such as translation, rotation, scaling, cropping, smoothing, simplification, and resampling, as well as malicious attacks such as the insertion of noise, modification of low-order bits, or even insertion of other watermarks.", organization = "ACM Siggraph", keywords = "copyright protection, steganography", } @InProceedings{EVL-1999-233, title = "Interpolating Nets of Curves by Smooth Subdivision Surface", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "57--64", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-233", author = "Adi Levin", abstract = "A subdivision algorithm is presented for the computation and representation of a smooth surface of arbitrary topological type interpolating a given net of smooth curves. The algorithm belongs to a new class of subdivision schemes called combined subdivision schemes. These schemes can exactly interpolate a net of curves given in any parametric representation. The surfaces generated by our algorithm are G2 except at a finite number of points, where the surface is G1 and has bounded curvature. The algorithm is simple and easy to implement, and is based on a variant of the famous Catmull-Clark subdivision scheme.", organization = "ACM Siggraph", keywords = "Subdivision, Interpolation, Combined Subdivision schemes, Net of curves", } @InProceedings{EVL-1999-234, title = "ArtDefo - Accurate Real Time Deformable Objects", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "65--72", year = "1999", author = "Doug L. James and Dinesh K. Pai", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-234", abstract = "We present an algorithm for fast, physically accurate simulation of deformable objects suitable for real time animation and virtual environment interaction. We describe the boundary integral equation formulation of static linear elasticity as well as the related Boundary Element Method (BEM) discretization technique. In addition, we show how to exploit the coherence of typical interactions to achieve low latency; the boundary formulation lends itself well to a fast update method when a few boundary conditions change. The algorithms are described in detail with examples from ArtDefo, our implementation.", organization = "ACM Siggraph", } @InProceedings{EVL-1999-235, title = "A Perceptually Based Physical Error Metric for Realistic Image Synthesis", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "73--82", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-235", author = "Mahesh Ramasubramanian and Sumanta N. Pattanaik and Donald P. Greenberg", abstract = "We introduce a new concept for accelerating realistic image synthesis algorithms. At the core of this procedure is a novel physical error metric that correctly predicts the perceptual threshold for detecting artifacts in scene features. Built into this metric is a computational model of the human visual system's loss of sensitivity at high background illumination levels, high spatial frequencies, and high contrast levels (visual masking). An important feature of our model is that it handles the luminance-dependent processing and spatially-dependent processing independently. This allows us to precompute the expensive spatially-dependent component, making our model extremely efficient. We illustrate the utility of our procedure with global illumination algorithms used for realistic image synthesis. The expense of global illumination computations is many orders of magnitude higher than the expense of direct illumination computations and can greatly benefit by applying our perceptually based technique. Results show our method preserves visual quality while achieving significant computational gains in areas of images with high frequency texture patterns, geometric details, and lighting variations.", organization = "ACM Siggraph", keywords = "Realistic Image Synthesis, Global Illumination, Adaptive Sampling, Perception, Visual Masking, Error Metric, Visual Threshol", } @InProceedings{EVL-1999-236, title = "Subdivision Schemes for Fluid Flow", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "111--120", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-236", author = "Henrik Weimer and Joe Warren", abstract = "The motion of fluids has been a topic of study for hundreds of years. In its most general setting, fluid flow is governed by a system of non-linear partial differential equations known as the Navier-Stokes equations. However, in several important settings, these equations degenerate into simpler systems of linear partial differential equations. This paper will show that flows corresponding to these linear equations can be modeled using subdivision schemes for vector fields. Given an initial, coarse vector field, these schemes generate an increasingly dense sequence of vector fields. The limit of this sequence is a continuous vector field defining a flow that follows the initial vector field. The beauty of this approach is that realistic flows can now be modeled and manipulated in real time using their associated subdivision schemes.", organization = "ACM Siggraph", keywords = "CAD, subdivision, multi-grid, fluid simulations, fractals, physically based animation, physically based modeling", } @InProceedings{EVL-1999-237, title = "{LCIS}: {A} Boundary Hierarchy for Detail-Preserving Contrast Reduction", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "83--90", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-237", author = "Jack Tumblin and Greg Turk", abstract = "High contrast scenes are difficult to depict on low contrast displays without loss of important fine details and textures. Skilled artists preserve these details by drawing scene contents in coarse-to-fine order using a hierarchy of scene boundaries and shadings. We build a similar hierarchy using multiple instances of a new low curvature image simplifier (LCIS), a partial differential equation inspired by anisotropic diffusion. Each LCIS reduces the scene to many smooth regions that are bounded by sharp gradient discontinuities, and a single parameter K chosen for each LCIS controls region size and boundary complexity. With a few chosen K values (K1 > K2 > K3...) LCIS makes a set of progressively simpler images, and image differences form a hierarchy of increasingly important details, boundaries and large features. We construct a high detail, low contrast display image from this hierarchy by compressing only the large features, then adding back all small details. Unlike linear filter hierarchies such as wavelets, filter banks, or image pyramids, LCIS hierarchies do not smooth across scene boundaries, avoiding {"}halo{"} artifacts common to previous contrast reducing methods and some tone reproduction operators. We demonstrate LCIS effectiveness on several example images.", organization = "ACM Siggraph", keywords = "Signal Processing, Displays, Non-Realistic Rendering, Level Of Detail Algorithms, Radiosity, Weird Math", } @InProceedings{EVL-1999-238, title = "A Practical Analytic Model for Daylight", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Grahics Procedings", publisher = "Addison Wesley Longman", pages = "91--100", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-238", author = "A. J. Preetham and Peter Shirley and Brian E. Smits.", abstract = "Sunlight and skylight are rarely rendered correctly in computer graphics. A major reason for this is high computational expense. Another is that precise atmospheric data is rarely available. We present an inexpensive analytic model that approximates full spectrum daylight for various atmospheric conditions. These conditions are parameterized using terms that users can either measure or estimate. We also present an inexpensive analytic model that approxi-mates the effects of atmosphere (aerial perspective). These models are fielded in a number of conditions and intermediate results verified against standard literature from atmospheric science. These models are analytic in the sense that they are simple formulas based on fits to simulated data; no explicit simulation is required to use them. Our goal is to achieve as much accuracy as possible without sacrificing usability.", organization = "ACM Siggraph", keywords = "sunlight, skylight, aerial perspective, illumination", } @InProceedings{EVL-1999-239, title = "Diffraction Shaders", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "101--110", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-239", author = "Jos Stam", abstract = "The reflection of light from surfaces is a fundamental problem in computer graphics. Although many reflection models have been proposed, few take into account the wave nature of light. In this paper, we derive a new class of reflection models for metallic surfaces that handle the effects of diffraction. Diffraction is a purely wave-like phenomenon and cannot be properly modeled using the ray theory of light alone. A common example of a surface which exhibits diffraction is the compact disk. A characteristic of such surfaces is that they reflect light in a very colorful manner. Our model is also a generalization of most reflection models encountered in computer graphics. In particular, we extend the He-Torrance model to handle anisotropic reflections. This is achieved by rederiving, in a more general setting, results from surface wave physics which were taken for granted by other researchers. Specifically, our use of Fourier analysis has enabled us to tackle the difficult task of analytically computing the Kirchhoff integral of surface scattering.", organization = "ACM Siggraph", keywords = "shading models, diffraction, Fourier transform, Kirchhoff theory, rough surface scattering, random processes", } @Article{EVL-1999-24, year = "1999", title = "A Distributed Spatial Architecture for Bush Fire Simulation", author = "Peter Eklund and Stephen Kirkby and Jonathan Mann", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-24", abstract = "This paper describes a spatial systems architecture allowing clients to modify parameters and run their own bush fire simulations via map data provided by a world wide web server. The simulations conform to the model of bush fire behaviors as well as operational requirements. A wavelet model and fire simulation over a distributed network are considered in this paper and we demonstrate how the architecture is general enough to accommodate other spatial simulations for emergency management using the world wide web.", volume = "3", keywords = "Distributed spatial information systems, web-based spatial simulation, bush fire modeling", number = "3", journal = "Transactions on GIS", publisher = "Blackwell Publishers Oxford", } @InProceedings{EVL-1999-240, title = "Stable Fluids", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "121--128", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-240", author = "Jos Stam", abstract = "Building animation tools for fluid-like motions is an important and challenging problem with many applications in computer graphics. The use of physics-based models for fluid flow can greatly assist in creating such tools. Physical models, unlike key frame or procedural based techniques, permit an animator to almost effortlessly create interesting, swirling fluid-like behaviors. Also, the interaction of flows with objects and virtual forces is handled elegantly. Until recently, it was believed that physical fluid models were too expensive to allow real-time interaction. This was largely due to the fact that previous models used unstable schemes to solve the physical equations governing a fluid. In this paper, for the first time, we propose an unconditionally stable model which still produces complex fluid-like flows. As well, our method is very easy to implement. The stability of our model allows us to take larger time steps and therefore achieve faster simulations. We have used our model in conjuction with advecting solid textures to create many fluid-like animations interactively in two- and three-dimensions.", organization = "ACM Siggraph", keywords = "animation of fluids, Navier-Stokes, stable solvers, implicit elliptic PDE solvers, interactive modeling, gaseous phenomena, advected textures", } @InProceedings{EVL-1999-241, title = "Computational Fluid Dynamics in a Traditional Animation Environment", address = "Los Angeles", editor = "Alyn Rockwood.", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "129--136", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-241", author = "Patrick Witting", abstract = "This paper presents a system that uses computational fluid dynamics to produce smoke, water, and other effects for traditionally-animated films. The system was used in over twenty scenes in the animated feature film {"}The Prince of Egypt.{"} Animators use images and animation sequences to drive two-dimensional numerical simulations of the time-dependent compressible Navier-Stokes equations. For instance, images can be used to initialize temperature fields which cause dynamic buoyancy-driven vortices to evolve. In addition to being image-driven, the systemis unique in allowing for compressibility of the fluid, and in its use of partial differential equations for texture mapping.", organization = "ACM Siggraph", keywords = "animation, animation systems, applications, fluid simulations, natural phenomena, numerical analysis, physically based animation, physically based modeling, scientific visualization, texture mapping", } @InProceedings{EVL-1999-242, title = "Graphical Modeling and Animation of Brittle", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Grpahics Proceedings", publisher = "Addison Wesley Longman", pages = "137--146", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-242", author = "James F. O'Brien and Jessica K. Hodgins", abstract = "In this paper, we augment existing techniques for simulating flexible objects to include models for crack initiation and propagation in three-dimensional volumes. By analyzing the stress tensors computed over a finite element model, the simulation determines where cracks should initiate and in what directions they should propagate. We demonstrate our results with animations of breaking bowls, cracking walls, and objects that fracture when they collide. By varying the shape of the objects, the material properties, and the initial conditions of the simulations, we can create strikingly different effects ranging from a wall that shatters when it is hit by a wrecking ball to a bowl that breaks in two when it is dropped on edge.", organization = "ACM Siggraph", keywords = "Animation techniques, physically based modeling, simulation, dynamics, fracture, cracking, deformation, finite element method", } @InProceedings{EVL-1999-243, title = "Direct Illumination With LazyVisibility Evaluation", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "147--154", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-243", author = "David Hart and Philip Dutr{\'{e}} and Donald P. Greenberg", abstract = "In this paper we present a technique for computing the direct lighting in a three-dimensional scene containing area light sources. Our method correctly handles partial visibility between luminaires and receivers, and is able to efficiently generate accurate soft shadows in scenes modeled with general bidirectional reflectance distribution functions. In most current algorithms, the form factor between a light source and receiver is computed using a stochastic ray casting approach which evaluates partial visibility. Such an approach often leads to noisy artifacts or aliasing problems. Generating significantly more rays is often the only solution to improving image quality. Our approach first stores visibility information in the image plane, using lazy evaluation of the visibility function. In a second phase, illumination values for each pixel are generated, using analytic or stochastic integration. Soft shadows and other shading effects are generated with high accuracy in less time than with existing shading algorithms. Coherence in specific blocker-light source relationships across the image plane is exploited to amortize the cost of analytic form factor calculations. By storing information in the image plane, our method is currently designed for generating a single image, and is thus view-dependent.", organization = "ACM Siggraph", keywords = "Rendering, Illumination Effects, Monte Carlo Techniques, Shadow Algorithms, Visibility Determination", } @InProceedings{EVL-1999-244, title = "Computing Exact Shadow Irradiance Using Splines", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "155--164", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-244", author = "Michael M. Stark and Elaine Cohen and Tom Lyche and Richard F. Riesenfeld", abstract = "We present a solution to the general problem of characterizing shadows in scenes involving a uniform polygonal area emitter and a polygonal occluder in arbitrary position by manifesting shadow irradiance as a spline function. Studying generalized prism-like constructions generated by the emitter and the occluder in a four-dimensional (shadow) space reveals a simpler intrinsic structure of the shadow as compared to the more complicated 2D projection onto a receiver. A closed form expression for the spline shadow irradiance function is derived by twice applying Stokes' theorem to reduce an evaluation over a 4D domain to an explicit formula involving only 2D faces on the receiver, derived the scene geometry. This leads to a straightforward computational algorithm and an interactive implementation. Moreover, this approach can be extended to scenes involving multiple emitters and occluders, as well as curved emitters, occluders, and receivers. Spline functions are constructed from these prism-like objects. We call them generalized polyhedral splines because they extend the classical polyhedral splines to include curved boundaries and a density function. The approach can be applied to more general problems such as some of those occurring in radiosity, and other related topics.", organization = "ACM Siggraph", keywords = "rendering, shadow algorithms, illumination, visibility determination", } @InProceedings{EVL-1999-245, title = "Reflection Space Image Based Rendering", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "165--170", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-245", author = "Brian Cabral and Marc Olano and Philip Nemec", abstract = "High quality, physically accurate rendering at interactive rates has widespread application, but is a daunting task. We attempt to bridge the gap between high-quality offline and interactive rendering by using existing environment mapping hardware in combination with a novel Image Based Rendering (IBR) algorithm. The primary contribution lies in performing IBR in reflection space. This method can be applied to ordinary environment maps, but for more physically accurate rendering, we apply reflection space IBR to radiance environment maps. A radiance environment map pre-integrates a Bidirectional Reflection Distribution Function (BRDF) with a lighting environment. Using the reflection-space IBR algorithm on ra-diance environment maps allows interactive rendering of arbitrary objects with a large class of complex BRDFs in arbitrary lighting environments. The ultimate simplicity of the final algorithm suggests that it will be widely and immediately valuable given the ready availability of hardware assisted environment mapping.", organization = "ACM Siggraph", keywords = "interactive rendering and shading, texture mapping, reflection mapping, image based rendering", } @InProceedings{EVL-1999-246, title = "Realistic, Hardware-Accelerated Shading and Lighting", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Annual Conference Proceedings", publisher = "Addison Wesley Longman", pages = "171--178", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-246", author = "Wolfgang Heidrich and Hans-Peter Seidel", abstract = "With fast 3D graphics becoming more and more available even on low end platforms, the focus in hardware-accelerated rendering is beginning to shift towards higher quality rendering and additional functionality instead of simply higher performance implementations based on the traditional graphics pipeline. In this paper we present techniques for realistic shading and lighting using computer graphics hardware. In particular, we discuss multipass methods for high quality local illumination using physically-based reflection models, as well as techniques for the interactive visualization of non-diffuse global illumination solutions. These results are then combined with normal mapping for increasing the visual complexity of rendered images Although the techniques presented in this paper work at interactive frame rates on contemporary graphics hardware, we also discuss some modifications of the rendering pipeline that help to further improve both performance and quality of the proposed methods", organization = "ACM Siggraph", keywords = "reflectance functions, illumination effects, shading, texture mapping, renderinghardware, frame buffer techniques", } @InProceedings{EVL-1999-247, title = "Tracing Ray Differential", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "179--186", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-247", author = "Homan Igehy", abstract = "Antialiasing of ray traced images is typically performed by super-sampling the image plane. While this type of filtering works well for many algorithms, it is much more efficient to perform filtering locally on a surface for algorithms such as texture mapping. In order to perform this type of filtering, one must not only trace the ray passing through the pixel, but also have some approximation of the distance to neighboring rays hitting the surface (i.e., a ray¹s footprint). In this paper, we present a fast, simple, robust scheme for tracking such a quantity based on ray differentials, derivatives of the ray with respect to the image plane.", organization = "ACM Siggraph", keywords = "color, shading, shadowing, and texture; raytracing", } @InProceedings{EVL-1999-248, title = "A Morphable Model for the Synthesis of 3{D} Faces", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "187--194", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-248", author = "Volker Blanz and Thomas Vetter", abstract = "In this paper, a new technique for modeling textured 3D faces is introduced. 3D faces can either be generated automatically from one or more photographs, or modeled directly through an intuitive user interface. Users are assisted in two key problems of computer aided face modeling. First, new face images or new 3D face models can be registered automatically by computing dense one-to-one correspondence to an internal face model. Second, the approach regulates the naturalness of modeled faces avoiding faces with an {"}unlikely{"} appearance. Starting from an example set of 3D face models, we derive a morphable face model by transforming the shape and texture of the examples into a vector space representation. New faces and expressions can be modeled by forming linear combinations of the prototypes. Shape and texture constraints derived from the statistics of our example faces are used to guide manual modeling or automated matching algorithms. We show 3D face reconstructions from single images and their applications for photo-realistic image manipulations. We also demonstrate face manipulations according to complex parameters such as gender, fullness of a face or its distinctiveness.", organization = "ACM Siggraph", keywords = "facial modeling, registration, photogrammetry, morphing, facial animation, computer vision", } @InProceedings{EVL-1999-249, title = "Creating Generative Models From Range Images", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "195--204", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-249", author = "Ravi Ramamoorthi and James Arvo", abstract = "We describe a new approach for creating concise high-level generative models from range images or other approximate representations of real objects. Using data from a variety of acquisition techniques and a user-defined class of models, our method produces a compact object representation that is intuitive and easy to edit. The algorithm has two inter-related phases: recognition, which chooses an appropriate model within a user-specified hierarchy, and parameter estimation, which adjusts the model to best fit the data. Since the approach is model-based, it is relatively insensitive to noise and missing data. We describe practical heuristics for automatically making tradeoffs between simplicity and accuracy to select the best model in a given hierarchy. We also describe a general and efficient technique for optimizing a model by refining its constituent curves. We demonstrate our approach for model recovery using both real and synthetic data and several generative model hierarchies.", organization = "ACM Siggraph", keywords = "Generative Models, Range Images, Curves and Surfaces, Procedural Modeling", } @Article{EVL-1999-25, pages = "3--16", year = "1999", title = "Linear complexity hexahedral mesh generation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-25", author = "David Eppstein", abstract = "We show that any polyhedron forming a topological ball with an even number of quadrilateral sides can be partitioned into O (n) topological cubes, meeting face to face. The result generalizes to non-simply-connected polyhedra satisfying an additional bipartiteness condition. The same techniques can also be used to reduce the geometric version of the hexahedral mesh generation problem to a finite case analysis amenable to machine solution.", month = feb, volume = "12", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-250, title = "Environment Matting and Compositing", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Sigggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "205--214", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-250", author = "Douglas E. Zongker and Dawn M. Werner and Brian Curless and David H. Salesin.", abstract = "This paper introduces a new process, environment matting,which captures not just a foreground object and its traditional opacity matte froma real-world scene, but also a description of how that object refracts and reflects light, which we call an environment matte. The foreground object can then be placed in a new environment, using environment compositing, where it will refract and reflect light from that scene. Objects captured in this way exhibit not only specular but glossy and translucent effects, as well as selective attenuation and scattering of light according to wavelength. Moreover, the environment compositing process, which can be performed largely with texture mapping operations, is fast enough to run at interactive speeds on a desktop PC. We compare our results to photos of the same objects in real scenes. Applications of this work include the relighting of objects for virtual and augmented reality, more realistic 3D clip art, and interactive lighting design.", organization = "ACM Siggraph", keywords = "environment matte, refraction, reflection, image-based rendering, environment map, augmented reality, interactive lighting design, clip art, alpha channel, blue-screen matting, blue spill, colored transparency", } @InProceedings{EVL-1999-251, title = "Inverse Global Illumination: Recovering Reflectance Models of Real Scenes From Photographs From", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph99, Annual Conference Series", publisher = "Addison Wesley Longman", pages = "215--224", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-251", author = "Yizhou Yu and Paul Debevec and Jitendra Malik and Tim Hawkins", abstract = "In this paper we present a method for recovering the reflectance properties of all surfaces in a real scene from a sparse set of photographs, taking into account both direct and indirect illumination. The result is a lighting-independent model of the scene's geometry and reflectance properties, which can be rendered with arbitrary modifications to structure and lighting via traditional rendering methods. Our technique models reflectance with a low-parameter reflectance model, and allows diffuse albedo to vary arbitrarily over surfaces while assuming that non-diffuse characteristics remain constant across particular regions. The method's input is a geometric model of the scene and a set of calibrated high dynamic range photographs taken with known direct illumination. The algorithm hierarchically partitions the scene into a polygonal mesh, and uses image-based rendering to construct estimates of both the radiance and irradiance of each patch from the photographic data. The algorithm computes the expected location of specular highlights, and then analyzes the highlight areas in the images by running a novel iterative optimization procedure to recover the diffuse and specular reflectance parameters for each region. Lastly, these parameters are used in constructing high-resolution diffuse albedo maps for each surface. The algorithm has been applied to both real and synthetic data, including a synthetic cubical room and a real meeting room. Re-renderings are produced using a global illumination system under both original and novel lighting, and with the addition of synthetic objects. Side-by-side comparisons show success at predicting the appearance of the scene under novel lighting conditions.", organization = "ACM Siggraph", keywords = "Global Illumination, Image-Based Modeling and Rendering, BRDF Models, Reflectance Recovery, Albedo Maps, Radiance, Radiosity, Rendering", } @InProceedings{EVL-1999-252, title = "Modeling and Rendering of Weathered Stone", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "225--234", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-252", author = "Julie Dorsey and Alan Edelman and Justin Legakis and Henrik Wann Jensen and Hans Kohling Pedersen", abstract = "Stone is widespread in its use as a building material and artistic medium. One of its most remarkable qualities is that it changes appearance as it interacts with the environment. These changes are mainly confined to the surface but involve complex volumetric effects such as erosion and mineral dissolution. This paper presents an approach for the modeling and rendering of changes in the shape and appearance of stone. To represent stone, we introduce a slab data structure, which is a surface-aligned volume confined to a narrow region around the boundary of the stone. Our weathering model employs a simulation of the flow of moisture and the transport, dissolution, and recrystallization of minerals within the porous stone volume. In addition, this model governs the erosion of material from the surface. To render the optical effects of translucency and coloration due to the composition of minerals near the surface, we simulate the scattering of light inside the stone using a general subsurface Monte Carlo ray tracer. These techniques can capture many aspects of the time-dependent appearance of stone. We demonstrate the approach with models of granite and marble statues, as well as a sandstone column.", organization = "ACM Siggraph", keywords = "erosion, material models, natural phenomena, physical simulation, ray tracing, subsurface scattering, texturing, volume modeling, weathering", } @InProceedings{EVL-1999-253, title = "Pattern-Based Texturing Revisited", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "235--242", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-253", author = "Fabrice Neyret and Marie-Paule Cani", abstract = "We present a texturing method that correctly maps homogeneous non-periodic textures to arbitrary surfaces without any of the difficulties usually encountered using existing tools. Our technique requires little redundant designer work, has low time and memory costs during rendering and provides high texture resolution. The idea is simple: a few triangular texture samples, which obey specific boundary conditions, are chosen from the desired pattern and mapped in a non-periodic fashion onto the surface. Our mapping algorithm enables us to freely tune the scale of the texture with respect to the object's geometry, while minimizing distortions. Moreover, it yields singularity-free texturing whatever the topology of the object. The sets of texture samples may be created interactively from pictures or drawings. We also provide two alternative methods for automatically generating them, defined as extensions of Perlin's and Worley's procedural texture synthesis techniques. As our results show, the method produces textured objects that look reasonable from any viewpoint and can be used in real-time applications.", organization = "ACM Siggraph", keywords = "Texture Mapping, Patterns, Texture Synthesis, Non-periodic Tiling", } @InProceedings{EVL-1999-254, title = "Feline: Fast Elliptical Lines for Anisotropic Texture Mapping", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "243--250", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-254", author = "Joel McCormack and Ronald Perry and Keith I. Farkas and Norman P. Jouppi", abstract = "Texture mapping using trilinearly filtered mip-mapped data is efficient and looks much better than point-sampled or bilinearly filtered data. But trilinear filtering represents the projection of a pixel filter footprint from screen space into texture space as a square, when in reality the footprint may be long and narrow. Consequently, trilinear filtering severely blurs images on surfaces angled obliquely away from the viewer This paper describes a new texture filtering technique called Feline (for Fast Elliptical Lines). Like other recent hardware anisotropic filtering algorithms, Feline uses an underlying space-invariant (isotropic) filter with mip-mapped data, and so can be built on top of an existing trilinear filtering engine. To texture a pixel, it uses this space-invariant filter at several points along a line in texture space, and combines the results. With a modest increase in implementation complexity over earlier techniques, Feline more accurately matches the desired projection of the pixel filter in texture space, resulting in images with fewer aliasing artifacts. Feline s visual quality compares well against Elliptical Weighted Average, the best software anisotropic texture filtering algorithm known to date, but Feline requires much less setup computation and far fewer cycles for texel fetches. Finally, since it uses standard mip-maps, Feline requires minimal extensions to standard 3D interfaces like OpenGL.", organization = "ACM Siggraph", keywords = "texture mapping, anisotropic filtering, space-variant filtering", } @InProceedings{EVL-1999-255, title = "The VolumePro Real-Time Ray-casting System", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings,", publisher = "Addison Wesley Longman", pages = "251--260", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-255", author = "Hanspeter Pfister and Jan Hardenbergh and Jim Knittel and Hugh Lauer and Larry Seiler", abstract = "This paper describes VolumePro, the world's first single-chip real-time volume rendering system for consumer PCs. VolumePro implements ray-casting with parallel slice-by-slice processing. Our discussion of the architecture focuses mainly on the rendering pipeline and the memory organization. VolumePro has hardware for gradient estimation, classification, and per-sample Phong illumination. The system does not perform any pre-processing and makes parameter adjustments and changes to the volume data immediately visible. We describe several advanced features of VolumePro, such as gradient magnitude modulation of opacity and illumination, supersampling, cropping and cut planes. The system renders 500 million interpolated, Phong illuminated, composited samples per second. This is sufficient to render volumes with up to 16 million voxels (e.g., 2563) at 30 frames per second.", organization = "ACM Siggraph", keywords = "Graphics Hardware, Hardware Systems, Rendering Hardware, Rendering Systems, Volume Renderin", } @InProceedings{EVL-1999-256, title = "Deep Compression for Streaming Texture Intensive Animations", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "261--268", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-256", author = "Daniel Cohen-Or and Yair Mann and Shachar Fleishman", abstract = "This paper presents a streaming technique for synthetic texture intensive 3D animation sequences. There is a short latency time while downloading the animation, until an initial fraction of the compressed data is read by the client. As the animation is played, the remainder of the data is streamed online seamlessly to the client. The technique exploits frame-to-frame coherence for transmitting geometric and texture streams. Instead of using the original textures of the model, the texture stream consists of view-dependent textures which are generated by rendering offline nearby views. These textures have a strong temporal coherency and can thus be well compressed. As a consequence, the bandwidth of the stream of the view-dependent textures is narrow enough to be transmitted together with the geometry stream over a low bandwidth network. These two streams maintain a small online cache of geometry and view-dependent textures from which the client renders the walk-through sequence in real-time. The overall data transmitted over the network is an order of magnitude smaller than an MPEG post-rendered sequence with an equivalent image quality.", organization = "ACM Siggraph", keywords = "compression, MPEG, streaming, virtual environment, image-based rendering", } @InProceedings{EVL-1999-257, title = "Optimization of Mesh Locality for Transparent Vertex Caching", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "269--276", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-257", author = "Hugues Hoppe", abstract = "Bus traffic between the graphics subsystem and memory can become a bottleneck when rendering geometrically complex meshes. In this paper, we investigate the use of vertex caching to transparently reduce geometry bandwidth. Use of an indexed triangle strip representation permits application programs to animate the meshes at video rates, and provides backward compatibility on legacy hardware. The efficiency of vertex caching is maximized by reordering the faces in the mesh during a preprocess. We present two reordering techniques, a fast greedy strip-growing algorithm and a local optimization algorithm. The strip-growing algorithm performs lookahead simulations of the cache to adapt strip lengths to the cache capacity. The local optimization algorithm improves this initial result by exploring a set of perturbations to the face ordering. The resulting cache miss rates are comparable to the efficiency of the earlier mesh buffer scheme described by Deering and Chow, even though the vertex cache is not actively managed.", organization = "ACM Siggraph", keywords = "geometry compression, triangle strips", } @InProceedings{EVL-1999-258, title = "A Real Time Low-Latency Hardware Light-Field Renderer", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annula Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "287--290", year = "1999", author = "Matthew J. P. Regan and Gavin S. P. Miller and Steven M. Rubin and Chris Kogelnik", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-258", abstract = "This paper describes the design and implementation of an architecture for interactively viewing static light fields with very low latency. The system was deliberately over engineered to specifications much tighter than expected necessary to eliminate perceptible latency. This allowed us to relax the specifications to the point at which human users began to detect latency artifacts. We found empirically that when interacting with a light field, human users began to notice latency artifacts when the total system latency is approximately 15 ms. Although the architecture may not be used in practice, this result should prove fundamental for designers of future interactive graphics systems.", organization = "ACM Siggraph", } @InProceedings{EVL-1999-259, title = "{LDI} Tree: {A} Hierarchical Representation for Image-Based Rendering", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "291--298", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-259", author = "Chun-Fa Chang and Gary Bishop and Anselmo Lastra", abstract = "Using multiple reference images in 3D image warping has been a challenging problem. Recently, the Layered Depth Image (LDI) was proposed by Shade et al. to merge multiple reference images under a single center of projection, while maintaining the simplicity of warping a single reference image. However it does not consider the issue of sampling rate. We present the LDI tree, which combines a hierarchical space partitioning scheme with the concept of the LDI. It preserves the sampling rates of the reference images by adaptively selecting an LDI in the LDI tree for each pixel. While rendering from the LDI tree, we only have to traverse the LDI tree to the levels that are comparable to the sampling rate of the output image. We also present a progressive refinement feature and a {"}gap filling{"} algorithm implemented by pre-filtering the LDI tree. We show that the amount of memory required has the same order of growth as the 2D reference images. This also bounds the complexity of rendering time to be less than directly rendering from all reference images.", organization = "ACM Siggraph", keywords = "image-based rendering, hierarchical representation", } @Article{EVL-1999-26, year = "1999", title = "Combinatorial and experimental results for randomized point matching algorithms", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-26", author = "Sandy Irani and Prabhakar Raghavan", abstract = "The subject of this paper is the design and analysis of Monte Carlo algorithms for two basic matching techniques used in model-based recognition: alignment, and geometric hashing. We first give analyses of our Monte Carlo algorithms, showing that they are asymptotically faster than their deterministic counterparts while allowing failure probabilities that are provably very small. We then describe experimental results that bear out this speed-up, suggesting that randomization results in significant improvements in running time. Our theoretical analyses are not the best possible; as a step to remedying this we define a combinatorial measure of self-similarity for point sets, and give an example of its power.", month = feb, volume = "12", keywords = "Model-based recognition; Geometric point matching; Randomized algorithms", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-260, title = "Rendering with Concentric Mosaics", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "299--306", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-260", author = "Heung-Yeung Shum and Li-Wei He", abstract = "This paper presents a novel 3D plenoptic function, which we call concentric mosaics. We constrain camera motion to planar concentric circles, and create concentric mosaics using a manifold mosaic for each circle (i.e., composing slit images taken at different locations). Concentric mosaics index all input image rays naturally in 3 parameters: radius, rotation angle and vertical elevation. Novel views are rendered by combining the appropriate captured rays in an efficient manner at rendering time. Although vertical distortions exist in the rendered images, they can be alleviated by depth correction. Like panoramas, concentric mosaics do not require recovering geometric and photometric scene models. Moreover, concentric mosaics provide a much richer user experience by allowing the user to move freely in a circular region and observe significant parallax and lighting changes. Compared with a Lightfield or Lumigraph, concentric mosaics have much smaller file size because only a 3D plenoptic function is constructed. Concentric mosaics have good space and computational efficiency, and are very easy to capture. This paper discusses a complete working system from capturing, construction, compression, to rendering of concentric mosaics from synthetic and real environments.", organization = "ACM Siggraph", keywords = "plenoptic functions, virtual environments, image-based rendering", } @InProceedings{EVL-1999-261, title = "Implicit Fairing of Irregular Meshes Using Diffusion and Curvature Flow", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "317--324", year = "1999", author = "Mathieu Desbrun and Mark Meyer and Peter Schr{\"{o}}der and Alan H. Barr", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-261", abstract = "In this paper, we develop methods to rapidly remove rough features from irregularly triangulated data intended to portray a smooth surface. The main task is to remove undesirable noise and uneven edges while retaining desirable geometric features. The problem arises mainly when creating high-fidelity computer graphics objects using imperfectly-measured data from the real world. Our approach contains three novel features: an implicit integration method to achieve efficiency, stability, and large time-steps; a scale-dependent Laplacian operator to improve the diffusion process; and finally, a robust curvature flow operator that achieves a smoothing of the shape itself, distinct from any parameterization. Additional features of the algorithm include automatic exact volume preservation, and hard and soft constraints on the positions of the points in the mesh. We compare our method to previous operators and related algorithms, and prove that our curvature and Laplacian operators have several mathematically-desirable qualities that improve the appearance of the resulting surface. In consequence, the user can easily select the appropriate operator according to the desired type of fairing. Finally, we provide a series of examples to graphically and numerically demonstrate the quality of our results.", organization = "ACM Siggraph", } @InProceedings{EVL-1999-262, title = "Automatic Image Placement to Provide a Guaranteed Frame Rate", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "307--316", year = "1999", author = "Daniel G. Aliaga and Anselmo Lastra", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-262", abstract = "We present a preprocessing algorithm and run-time system for rendering 3D geometric models at a guaranteed frame rate. Our approach trades off space for frame rate by using images to replace distant geometry. The preprocessing algorithm automatically chooses a subset of the model to display as an image so as to render no more than a specified number of geometric primitives. We also summarize an optimized layered-depth-image warper to display images surrounded by geometry at run time. Furthermore, we show the results of applying our method to accelerate the interactive walkthrough of several complex models.", organization = "ACM Siggraph", } @InProceedings{EVL-1999-263, title = "Multiresolution Signal Processing for Meshes", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "325--334", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-263", author = "Igor Guskov and Wim Sweldens and Peter Schr{\"{o}}der", abstract = "We generalize basic signal processing tools such as downsampling, upsampling, and filters to irregular connectivity triangle meshes. This is accomplished through the design of a non-uniform relaxation procedure whose weights depend on the geometry and we show its superiority over existing schemes whose weights depend only on connectivity. This is combined with known mesh simplification methods to build subdivision and pyramid algorithms. We demonstrate the power of these algorithms through a number of application examples including smoothing, enhancement, editing, and texture mapping.", organization = "ACM Siggraph", keywords = "Meshes, subdivision, irregular connectivity, surface parameterization, multiresolution, wavelets, Laplacian Pyramid", } @InProceedings{EVL-1999-264, title = "Shape Transformation Using Variational Implicit Functions", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "1999", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-264", author = "Greg Turk and James O'Brien", abstract = "Traditionally, shape transformation using implicit functions is performed in two distinct steps: 1) creating two implicit functions, and 2) interpolating between these two functions. We present a new shape transformation method that combines these two tasks into a single step. We create a transformation between two N-dimensional objects by casting this as a scattered data interpolation problem in N + 1 dimensions. For the case of 2D shapes, we place all of our data constraints within two planes, one for each shape. These planes are placed parallel to one another in 3D. Zero-valued constraints specify the locations of shape boundaries and positive-valued constraints are placed along the normal direction in towards the center of the shape. We then invoke a variational interpolation technique (the 3D generalization of thin-plate interpolation), and this yields a single implicit function in 3D. Intermediate shapes are simply the zero-valued contours of 2D slices through this 3D function. Shape transformation between 3D shapes can be performed similarly by solving a 4D interpolation problem. To our knowledge, ours is the first shape transformation method to unify the tasks of implicit function creation and interpolation. The transformations produced by this method appear smooth and natural, even between objects of differing topologies. If desired, one or more additional shapes may be introduced that influence the intermediate shapes in a sequence. Our method can also reconstruct surfaces from multiple slices that are not restricted to being parallel to one another.", organization = "ACM Siggraph", keywords = "Shape transformation, shape morphing, contour interpolation, implicit surfaces, thin-plate techniques", } @InProceedings{EVL-1999-265, title = "Multiresolution Mesh Morphing", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "343--350", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-265", author = "Aaron Lee and David Dobkin and Wim Sweldens and Peter Schr{\"{o}}der", abstract = "We present a new method for user controlled morphing of two homeomorphic triangle meshes of arbitrary topology. In particular we focus on the problem of establishing a correspondence map between source and target meshes. Our method employs the MAPS algorithm to parameterize both meshes over simple base domains and an additional harmonic map bringing the latter into correspondence. To control the mapping the user specifies any number of feature pairs, which control the parameterizations produced by the MAPS algorithm. Additional controls are provided through a direct manipulation interface allowing the user to tune the mapping between the base domains. We give several examples of aesthetically pleasing morphs which can be created in this manner with little user input. Additionally we demonstrate examples of temporal and spatial control over the morph.", organization = "ACM Siggraph", keywords = "Meshes, surface parameterization, mesh simplification, multiresolution, interpolation, morphing", } @InProceedings{EVL-1999-266, title = "Balancing Fusion, Image Depth and Distortion in Stereoscopic Head-Tracked Displays", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "351--358", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-266", author = "Zachary Wartell and Larry F. Hodges and William Ribarsky", abstract = "Stereoscopic display is a fundamental part of virtual reality HMD systems and HTD (head-tracked display) systems such as the virtual workbench and the CAVE. A common practice in stereoscopic systems is deliberate incorrect modeling of user eye separation. Underestimating eye separation is frequently necessary for the human visual system to fuse stereo image pairs into single 3D images, while overestimating eye separation enhances image depth. Unfortunately, false eye separation modeling also distorts the perceived 3D image in undesirable ways. This paper makes three fundamental contributions to understanding and controlling this stereo distortion. (1) We analyze the distortion using a new analytic description. This analysis shows that even with perfect head tracking, a user will perceive virtual objects to warp and shift as she moves her head. (2) We present a new technique for counteracting the shearing component of the distortion. (3) We present improved methods for managing image fusion problems for distant objects and for enhancing the depth of flat scenes.", organization = "ACM Siggraph", keywords = "virtual reality, stereoscopic display, head-tracking, image distortion", } @InProceedings{EVL-1999-267, title = "Walking > Walking-in-Place > Flying, in Virtual Environments", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "359--364", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-267", author = "Martin Usoh and Kevin Arthur and Mary C. Whitton and Rui Bastos and Anthony Steed and Mel Slater and Jr. Frederick P. Brooks", abstract = "A study by Slater, et al., [1995] indicated that naive subjects in an immersive virtual environment experience a higher subjective sense of presence when they locomote by walking-in-place (virtual walking) than when they push-button-fly (along the floor plane). We replicated their study, adding real walking as a third condition. Our study confirmed their findings. We also found that real walking is significantly better than both virtual walking and flying in ease (simplicity, straightforwardness, naturalness) as a mode of locomotion. The greatest difference in subjective presence was between flyers and both kinds of walkers. In addition, subjective presence was higher for real walkers than virtual walkers, but the difference was statistically significant only in some models. Follow-on studies show virtual walking can be substantially improved by detecting footfalls with a head accelerometer. As in the Slater study, subjective presence significantly correlated with subjects' degree of association with their virtual bodies (avatars). This, our strongest statistical result, suggests that substantial potential presence gains can be had from tracking all limbs and customizing avatar appearance. An unexpected by-product was that real walking through our enhanced version of Slater's visual-cliff virtual environment (Figure 1) yielded a strikingly compelling virtual experiencethe strongest we and most of our visitors have yet experienced. The most needed system improvement is the substitution of wireless technology for all links to the user.", organization = "ACM Siggraph", keywords = "Presence, Locomotion, Virtual Reality, Virtual Walking, Human Factors, Neural Networks, Visual Cliff", } @InProceedings{EVL-1999-268, title = "Real-Time Acoustic Modeling for Distributed Virtual Environments", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longma", pages = "365--374", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-268", author = "Thomas A. Funkhouser and Patrick Min and Ingrid Carlbom", abstract = "Realistic acoustic modeling is essential for spatializing sound in distributed virtual environments where multiple networked users move around and interact visually and aurally in a shared virtual world. Unfortunately, current methods for computing accurate acoustical models are not fast enough for real-time auralization of sounds for simultaneously moving sources and receivers. In this paper, we present three new beam tracing algorithms that greatly accelerate computation of reverberation paths in a distributed virtual environment by taking advantage of the fact that sounds can only be generated or heard at the positions of {"}avatars{"} representing the users. The priority-driven beam tracing algorithm performs a best-first search of a cell adjacency graph, and thus enables new termination criteria with which all early reflection paths can be found very efficiently. The bidirectional beam tracing algorithm combines sets of beams traced from pairs of avatar locations to find reverberation paths between them while requiring significantly less computation than previous unidirectional algorithms. The amortized beam tracing algorithm computes beams emanating from box-shaped regions of space containing predicted avatar locations and re-uses those beams multiple times to compute reflections paths as each avatar moves inside the box. Cumulatively, these algorithms enable speedups of approximately two orders of magnitude over previous methods. They are incorporated into a time-critical multiprocessing system that allocates its computational resources dynamically in order to compute the highest priority reverberation paths between moving avatar locations in real-time with graceful degradation and adaptive refinement.", organization = "ACM Siggraph", keywords = "Virtual environment systems, virtual reality, acoustic modeling, auralization, beam tracing", } @InProceedings{EVL-1999-269, title = "Six Degrees-of-Freedom Haptic Rendering Using Voxel Sampling", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "401--408", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-269", author = "William A. McNeely and Kevin D. Puterbaugh and James J. Troy", abstract = "A simple, fast, and approximate voxel-based approach to 6-DOF haptic rendering is presented. It can reliably sustain a 1000 Hz haptic refresh rate without resorting to asynchronous physics and haptic rendering loops. It enables the manipulation of a modestly complex rigid object within an arbitrarily complex environment of static rigid objects. It renders a short-range force field surrounding the static objects, which repels the manipulated object and strives to maintain a voxel-scale minimum separation distance that is known to preclude exact surface interpenetration. Force discontinuities arising from the use of a simple penalty force model are mitigated by a dynamic simulation based on virtual coupling. A generalization of octree improves voxel memory efficiency. In a preliminary implementation, a commercially available 6-DOF haptic prototype device is driven at a constant 1000 Hz haptic refresh rate from one dedicated haptic processor, with a separate processor for graphics. This system yields stable and convincing force feedback for a wide range of user controlled motion inside a large, complex virtual environment, with very few surface inter-penetration events. This level of performance appears suited to applications such as certain maintenance and assembly task simulations that can tolerate voxel-scale minimum separation distances.", organization = "ACM Siggraph", keywords = "force feedback, voxel representations, virtual environments", } @Article{EVL-1999-27, pages = "33--44", year = "1999", title = "On the bit complexity of minimum link paths: Superquadratic algorithms for problem solvable in linear time", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-27", author = "Simon Kahan and Jack Snoeyink", abstract = "All of the linear-time algorithms that have been developed for minimum-link paths use the real RAM model of computation. If one considers bit complexity, however, merely representing a minimum-link path may require a superquadratic number of bits. This paper considers bounds on the number of links (segments) needed by limited-precision approximations of minimum-link paths: When vertices are restricted to {"}first-derived{"} points, the number of links can increase by a constant factor; when they are restricted to points of an N×N grid, the number of links can increase by $\Theta(log N)$.", month = feb, volume = "12", keywords = "Simple polygons; Link paths; Exact geometric computation; Grid geometry", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-270, title = "Creating a Live Broadcast from a Virtual Environment", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "375--384", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-270", author = "Chris Greenhalgh and Steve Benford and Ian Taylor and John Bowers and Graham Walker and John Wyver", abstract = "{"}Inhabited Television{"} combines multiuser virtual environments with television, so that online audience-members can participate in TV shows staged in a virtual world. It is presented simultaneously both to conventional passive viewers and to online participants. In many cases it benefits from being broadcast live. This paper is based on our fourth major experiment with Inhabited TV, a live virtual game show called {"}Out Of This World.{"} For this event we adopted non-automated approaches to camera control and mixing to allow an exploration of appropriate forms of presentation for inhabited television. We describe the techniques which were used to create and enhance the live video output which was produced during the show: appropriate world design; dynamic constraints on participant movements; and a performance-oriented virtual camera control interface. This camera control interface includes explicit support for a range of spatial and temporal control styles. We also give evaluative feedback on the camera control interface and the event's (television-based) approach to mixing and directing, drawing on a social scientific field study conducted on-site during the preparation for, and performances of, the show.", organization = "ACM Siggraph", keywords = "Multi-User, Networked Apps, Video, Viewpoint control", } @InProceedings{EVL-1999-271, title = "Emancipated Pixels: Real-World Graphics in the Luminous Room", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "385--392", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-271", author = "John Underkoffler and Brygg Ullmer and Hiroshi Ishii", abstract = "We describe a conceptual infrastructure - the Luminous Room - for providing graphical display and interaction at each of an interior architectural space's various surfaces, arguing that pervasive environmental output and input is one natural heir to today's rather more limited notion of spatially-confined, output-only display (the CRT). We discuss the requirements of such real-world graphics, including computational & networking demands; schemes for spatially omnipresent capture and display; and issues of design and interaction that emerge under these new circumstances. These discussions are both illustrated and motivated by five particular applications that have been built for a real, experimental Luminous Room space, and by details of the current technical approach to its construction (involving a two-way optical transducer called an I/O Bulb that projects and captures pixels).", organization = "ACM Siggraph", keywords = "real-world graphics, luminous-tangible interfaces, projection, computer vision, architectural space, CAD", } @InProceedings{EVL-1999-272, title = "Skin: {A} Constructive Approach to Modeling Free-form Shapes", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "393--400", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-272", author = "Lee Markosian and Jonathan M. Cohen and Thomas Crulli and John F. Hughes", abstract = "We present a new particle-based surface representation with which a user can interactively sculpt free-form surfaces. The particles maintain mesh connectivity and operate under rules that lead them to form triangulations with properties that make them suitable for use in subdivision. A user interactively guides the particles, which we call skin, to grow over a given collection of polyhedral elements (or skeletons), yielding a smooth surface (through subdivision) that approximates the underlying skeletal shapes. Skin resembles blobby modeling in the constructive approach to modeling it supports, but allows a richer vocabulary of skeleton shapes, supports sharp creases where desired, and provides a convenient mechanism for adding multiresolution surface detail.", organization = "ACM Siggraph", keywords = "Free-form modeling, meshes, subdivision, multiresolution", } @InProceedings{EVL-1999-273, title = "Teddy: {A} Sketching Interface for 3{D} Freeform Design", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Srries", booktitle = "Siggraph 1999", publisher = "Addison Wesley Longman", pages = "409--416", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-273", author = "Takeo Igarashi and Satoshi Matsuoka and Hidehiko Tanaka", abstract = "We present a sketching interface for quickly and easily designing freeform models such as stuffed animals and other rotund objects. The user draws several 2D freeform strokes interactively on the screen and the system automatically constructs plausible 3D polygonal surfaces. Our system supports several modeling operations, including the operation to construct a 3D polygonal surface from a 2D silhouette drawn by the user: it inflates the region surrounded by the silhouette making wide areas fat, and narrow areas thin. Teddy, our prototype system, is implemented as a Java program, and the mesh construction is done in real-time on a standard PC. Our informal user study showed that a first-time user typically masters the operations within 10 minutes, and can construct interesting 3D models within minutes.", organization = "ACM Siggraph", keywords = "3D modeling, sketching, pen-based systems, gestures, design, chordal axes, inflation", } @InProceedings{EVL-1999-274, title = "Digital Facial Engraving", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer graphics Proceedings", publisher = "Los Angeles", pages = "417--424", year = "1999", author = "Victor Ostromoukhov", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-274", abstract = "This contribution introduces the basic techniques for digital facial engraving, which imitates traditional copperplate engraving. Inspired by traditional techniques, we first establish a set of basic rules thanks to which separate engraving layers are built on the top of the original photo. Separate layers are merged according to simple merging rules and according to range shift/scale masks specially introduced for this purpose. We illustrate the introduced technique by a set of black/white and color engravings, showing different features such as engraving-specific image enhancements, mixing different regular engraving lines with mezzotint, irregular perturbations of engraving lines etc. We introduce the notion of engraving style which comprises a set of separate engraving layers together with a set of associated range shift/scale masks. The engraving style helps to port the look and feel of one engraving to another. Once different libraries of pre-defined mappable engraving styles and an appropriate user interface are added to the basic system, producing a decent gravure starting from a simple digital photo will be a matter of seconds. The engraving technique described in this contribution opens new perspectives for digital art, adding unprecedented power and precision to the engraver's work.", organization = "ACM Siggraph", keywords = "photorealistic rendering, nonphotorealistic rendering, halftoning, dithering, digital engraving", } @InProceedings{EVL-1999-275, title = "Multi-Color and Artistic Dithering", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "425--432", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-275", author = "Victor Ostromoukhov and Roger D. Hersch", abstract = "A multi-color dithering algorithm is proposed, which converts a barycentric combination of color intensities into a multi-color non-overlapping surface coverage. Multi-color dithering is a generalization of standard bi-level dithering. Combined with tetrahedral color separation, multi-color dithering makes it possible to print images made of a set of non-standard inks. In contrast to most previous color halftoning methods, multi-color dithering ensures by construction that the different selected basic colors are printed side by side. Multi-color dithering is applied to generate color images whose screen dots are made of artistic shapes (letters, symbols, ornaments, etc.). Two dither matrix postprocessing techniques are developed, one for enhancing the visibility of screen motives and one for the local equilibration of large dither matrices. The dither matrix equilibration process corrects disturbing local intensity variations by taking dot gain and the human visual system transfer function into account. Thanks to the combination of the presented techniques, high quality images can be produced, which incorporate at the micro level the desired artistic screens and at the macro level the full color image. Applications include designs for advertisements and posters as well as security printing. Multi-color dithering also offers new perspectives for printing with special inks, such as fluorescent and metallic inks.", organization = "ACM Siggraph", keywords = "color halftoning, artistic dithering, dither matrix equilibration, non-standard inks, side by side printing", } @InProceedings{EVL-1999-276, title = "Art-Based Rendering of Fur, Grass, and Trees", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "433--438", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-276", author = "Michael A. Kowalski and Lee Markosian and J. D. Northrup and Lubomir Bourdev and Ronen Barzel and Loring S. Holden and John Hughes", abstract = "Artists and illustrators can evoke the complexity of fur or vegetation with relatively few well-placed strokes. We present an algorithm that uses strokes to render 3D computer graphics scenes in a stylized manner suggesting the complexity of the scene without representing it explicitly. The basic algorithm is customizable to produce a range of effects including fur, grass and trees, as we demonstrate in this paper and accompanying video. The algorithm is implemented within a broader framework that supports procedural stroke-based textures on polyhedral models. It renders mod-erately complex scenes at multiple frames per second on current graphics workstations, and provides some interframe coherence.", organization = "ACM Siggraph", keywords = "Non-photorealistic rendering, graftals, procedural textures", } @InProceedings{EVL-1999-277, title = "View-Dependent Geometry", address = "Los Angeles", editor = "Alyn Rockwood", series = "Annual Conference Series", booktitle = "Siggraph 1999, Computer Graphics Proceedings", publisher = "Addison Wesley Longman", pages = "439--446", year = "1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-277", author = "Paul Rademacher", abstract = "When constructing 3D geometry for use in cel animation, the reference drawings of the object or character often contain various view-specific distortions, which cannot be captured with conventional 3D models. In this work we present a technique called View-Dependent Geometry, wherein a 3D model changes shape based on the direction it is viewed from. A view-dependent model consists of a base model, a set of key deformations (deformed versions of the base model), and a set of corresponding key viewpoints (which relate each 2D reference drawing to the 3D base model). Given an arbitrary viewpoint, our method interpolates the key deformations to generate a 3D model that is specific to the new viewpoint, thereby capturing the view-dependent distortions of the reference drawings.", organization = "ACM Siggraph", keywords = "Cartoon animation, 3D animation, rendering, animation systems, non-photorealistic rendering, 3D blending", } @InProceedings{EVL-1999-278, pages = "19--26", year = "1999", title = "Construction of Vector Field Hierarchies", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-278", author = "Bjoern Heckel and Gunther H. Weber and Bernd Hamann and Kenneth I. Joy", abstract = "We present a method for the hierarchical representation of vector fields. Our approach is based on iterative refinement using clustering and principal component analysis. The input to our algorithm is a discrete set of points with associated vectors. The algorithm generates a top-down segmentation of the discrete field by splitting clusters of points. We measure the error of the various approximation levels by measuring the discrepancy between streamlines generated by the original discrete field and its approximations based on much smaller discrete data sets. Our method assumes no particular structure of the field, nor does it require any topological connectivity information. It is possible to generate multiresolution representations of vector fields using this approach.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "vector field visualization; Hardy's multiquadric method; binary-space partitioning; data simplification", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-279, pages = "27--34", year = "1999", title = "Large Field Visualization With Demand-Driven Calculation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-279", author = "Patrick J. Moran and Chris Henze", abstract = "We present a system designed for the interactive definition and visualization of fields derived from large data sets: the Demand-Driven Visualizer (DDV). The system allows the user to write arbitrary expressions to define new fields, and then apply a variety of visualization techniques to the result. Expressions can include differential operators and numerous other built-in functions. Determination of field values, both in space and in time, is directed automatically by the demands of the visualization techniques. The payoff of following a demand-driven design philosophy throughout the visualization system becomes particularly evident when working with large time-series data, where the costs of eager evaluation alternatives can be prohibitive.", organization = "IEEE", address = "San Francisco", editor = "Edited by David Ebert and Markus Gross and Bernd Hamann", keywords = "arge scale visualization, scientific visualization, interactive visualization, demand-driven evaluation, lazy evaluation, interpreted systems, Python", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-28, pages = "45--62", year = "1999", title = "Partial surface matching by using directed footprints", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-28", author = "Gill Barequet and Micha Sharir", abstract = "In this paper we present a new technique for partial surface and volume matching of images in three dimensions. In this problem, we are given two objects in 3-space, each represented as a set of points, scattered uniformly along its boundary or inside its volume. The goal is to find a rigid motion of one object which makes a sufficiently large portion of its boundary lying sufficiently close to a corresponding portion of the boundary of the second object. This is an important problem in pattern recognition and in computer vision, with many industrial, medical, and chemical applications. Our algorithm is based on assigning a directed footprint to every point of the two sets, and locating all the pairs of points (one of each set) whose undirected components of the footprints are sufficiently similar. The algorithm then computes for each such pair of points all the rigid transformations that map the first point to the second, while making the respective direction components of their footprints coincide. A voting scheme is employed for computing transformations which map significantly large number of points of the first set to points of the second set. Experimental results on various examples are presented and show the accurate and robust performance of our algorithm.", month = feb, volume = "12", keywords = "Geometric hashing; Computer vision; Pattern recognition; Partial surface matching", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-280, pages = "35--42", year = "1999", title = "Simplified Representation of Vector Fields", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-280", author = "Alexandru Telea and Jarke J. van Wijk", abstract = "Vector field visualization remains a difficult task. Although many local and global visualization methods for vector fields such as flow data exist, they usually require extensive user experience on setting the visualization parameters in order to produce images communicating the desired insight. We present a visualization method that produces simplified but suggestive images of the vector field automatically, based on a hierarchical clustering of the input data. The resulting clusters are then visualized with straight or curved arrow icons. The presented method has a few parameters with which users can produce various simplified vector field visualizations that communicate different insights on the vector data", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Flow Visualization, Simplification, Clustering", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-281, pages = "43--50", year = "1999", title = "Hierarchical Parallel Coordinates for Exploration of Large Datasets", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-281", author = "Ying-Huey Fua and Matthew O. Ward and Elke A. Rundensteiner", abstract = "Our ability to accumulate large, complex (multivariate) data sets has far exceeded our ability to effectively process them in search of patterns, anomalies, and other interesting features. Conventional multivariate visualization techniques generally do not scale well with respect to the size of the data set. The focus of this paper is on the interactive visualization of large multivariate data sets based on a number of novel extensions to the parallel coordinates display technique. We develop a multiresolutional view of the data via hierarchical clustering, and use a variation on parallel coordinates to convey aggregation information for the resulting clusters. Users can then navigate the resulting structure until the desired focus region and level of detail is reached, using our suite of navigational and filtering tools. We describe the design and implementation of our hierarchical parallel coordinates system which is based on extending the XmdvTool system. Lastly, we show examples of the tools and techniques applied to large (hundreds of thousands of records) multivariate data sets.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Large-scale multivariate data visualization, hierarchical data exploration, parallel coordinates", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-282, pages = "67--72", year = "1999", title = "Progressive Compression of Arbitrary Triangular Meshes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-282", author = "Daniel Cohen-Or and David Levin and Offir Remez", abstract = "In this paper we present a mesh compression method based on a multiresolution decomposition whose detail coefficients have a compact representation and thus smaller entropy than the original mesh. Given an arbitrary triangular mesh with an irregular connectivity, we use a hierarchical simplification scheme, which generates a multiresolution model. By reversing the process we define a hierarchical progressive refinement process, where a simple prediction plus a correction is used for inserting vertices to form a finer level. We show how the connectivity of an arbitrary triangulation can be encoded efficiently by a coloring technique, and recovered incrementally during the progressive reconstruction of the original mesh.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "compression, streaming, progressive meshes, simplification", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-283, pages = "51--58", year = "1999", title = "Tetrahedral Mesh Compression with the Cut-Border Machine", author = "Stefan Gumhold and Stefan Guthe and Wolfgang Stra{\ss{}}er", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-283", abstract = "In recent years, substantial progress has been achieved in the area of volume visualization on irregular grids, which is mainly based on tetrahedral meshes. Even moderately fine tetrahedral meshes consume several mega-bytes of storage. For archivation and transmission compression algorithms are essential. In scientific applications lossless compression schemes are of primary interest. This paper introduces a new lossless compression scheme for the connectivity of tetrahedral meshes. Our technique can handle all tetrahedral meshes in three dimensional euclidean space even with non manifold border. We present compression and decompression algorithms which consume for reasonable meshes linear time in the number of tetrahedra. The connectivity is compressed to less than 2.4 bits per tetrahedron for all measured meshes. Thus a tetrahedral mesh can almost be reduced to the vertex coordinates, which consume in a common representation about one quarter of the total storage space. We complete our work with solutions for the compression of vertex coordinates and additional attributes, which might be attached to the mesh.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "compression algorithms, solid modeling, scientific visualization, volume rendering", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-284, pages = "59--66", year = "1999", title = "New Quadric Metric for Simplifying Meshes with Appearance Attributes", author = "Hugues H. Hoppe", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-284", abstract = "Complex triangle meshes arise naturally in many areas of computer graphics and visualization. Previous work has shown that a quadric error metric allows fast and accurate geometric simplification of meshes. This quadric approach was recently generalized to handle meshes with appearance attributes. In this paper we present an improved quadric error metric for simplifying meshes with attributes. The new metric, based on geometric correspondence in 3D, requires less storage, evaluates more quickly, and results in more accurate simplified meshes. Meshes often have attribute discontinuities, such as surface creases and material boundaries, which require multiple attribute vectors per vertex. We show that a wedge-based mesh data structure captures such discontinuities efficiently and permits simultaneous optimization of these multiple attribute vectors. In addition to the new quadric metric, we experiment with two techniques proposed in geometric simplification, memoryless simplification and volume preservation, and show that both of these are beneficial within the quadric framework. The new scheme is demonstrated on a variety of meshes with colors and normals.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "level of detail, mesh decimation, multiresolution", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-285, pages = "81--88", year = "1999", title = "Image Graphs - {A} Novel Approach to Visual Data Exploration", author = "Kwan-Liu Ma", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-285", abstract = "For types of data visualization where the cost of producing images is high, and the relationship between the rendering parameters and the image produced is less than obvious, a visual representation of the exploration process can make the process more effcient and effective. Image graphs represent not only the results but also the process of data visualization. Each node in an image graph consists of an image and the corresponding visualization parameters used to produce it. Each edge in a graph shows the change in rendering parameters between the two nodes it connects. Image graphs are not just static representations: users can interact with a graph to review a previous visualization session or to perform new rendering. Operations which cause changes in rendering parameters can propagate through the graph. The user can take advantage of the information in image graphs to understand how certain parameter changes affect visualization results. Users can also share image graphs to streamline the process of collaborative visualization. We have implemented a volume visualization system using the image graph interface, and our examples in the paper come from this application.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "knowledge representations, scientific visualization, visualization systems, volume renderin", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-286, pages = "89--96", year = "1999", title = "Forward Image Warping", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-286", author = "Baoquan Chen and Frank Dachille and Arie E. Kaufman", abstract = "We present a new forward image mapping algorithm, which speeds up perspective warping - as in texture mapping. It processes the source image in a special scanline order instead of the normal raster scanline order. This special scanline has the property of preserving parallelism when projecting to the target image. The algorithm reduces the complexity of perspective-correct image warping by eliminating the division per pixel and replacing it with a division per scanline. The method also corrects the perspective distortion in Gouraud shading with negligible overhead. Furthermore, the special scanline order is suitable for antialiasing using a more accurate antialiasing conic filter, with minimum additional cost. The algorithm is highlighted by incremental calculations and optimized memory bandwidth by reading each source pixel only once, suggesting a potential hardware implementation.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "image warping, forward mapping, texture mapping, antialiasing, anisotropic filtering, Gouraud shading, hardware", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-287, pages = "97--104", year = "1999", title = "Structured Spatial Domain Image and Data Comparison Metrics", author = "Nivedita Sahasrabudhe and John E. West and Raghu Machiraju and Mark Janus", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-287", abstract = "Often, images or datasets have to be compared, to facilitate choices of visualization and simulation parameters respectively. Common comparison techniques include side-by-side viewing and juxtaposition, in order to facilitate visual verification of verisimilitude. In this paper, we propose quantitative techniques which accentuate differences in images and datasets. The comparison is enabled through a collection of partial metrics which, essentially, measure the lack of correlation between the datasets or images being compared. That is, they attempt to expose and measure the extent of the inherent structures in the difference between images or datasets. Besides yielding numerical attributes, the metrics also produce images, which can visually highlight differences. Our metrics are simple to compute and operate in the spatial domain. We demonstrate the effectiveness of our metrics through examples for comparing images and datasets.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "metrics, steering, rendering, correlation measure", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-288, pages = "105--114", year = "1999", title = "Feature Comparisons Of 3-{D} Vector Fields Using Earth Mover's Distance", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-288", author = "Rajesh K. Batra and Lambertus Hesselink", abstract = "A method for comparing three-dimensional vector fields constructed from simple critical points is described. This method is a natural extension of the previous work [1] which defined a distance metric for comparing two-dimensional fields The extension to three-dimensions follows the path of our previous work, rethinking the representation of a critical point signature and the distance measure between the points. Since the method relies on topologically based information, problems such as grid matching and vector alignment which often complicate other comparison techniques are avoided. In addition, since only feature information is used to represent, and therefore stored for each field, a significant amount of compression occurs.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-289, pages = "115--122", year = "1999", title = "Rendering on a Budget: {A} Framework for Time-Critical Rendering", author = "James T. Klosowski and Cl{\'{a}}udio T. Silva", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-289", abstract = "We present a technique for optimizing the rendering of high-depth complexity scenes. Prioritized-Layered Projection (PLP) does this by rendering an estimation of the visible set for each frame. The novelty in our work lies in the fact that we do not explicitly compute visible sets. Instead, our work is based on computing on demand a priority order for the polygons that maximizes the likelihood of rendering visible polygons before occluded ones for any given scene. Given a fixed budget, e.g. time or number of triangles, our rendering algorithm makes sure to render geometry respecting the computed priority. There are two main steps to our technique: (1) an occupancy-based tessellation of space; and (2) a solidity-based traversal algorithm. PLP works by computing an occupancy-based tessellation of space, which tends to have smaller cells where there are more geometric primitives, e.g., polygons. In this spatial tessellation, each cell is assigned a solidity value, which is directly proportional to its likelihood of occluding other cells. In its simplest form, a cell's solidity value is directly proportional to the number of polygons contained within it. During our traversal algorithm, cells are marked for projection, and the geometric primitives contained within them actually rendered. The traversal algorithm makes use of the cells' solidity, and other view-dependent information to determine the ordering in which to project cells. By tailoring the traversal algorithm to the occupancy-based tessellation, we can achieve very good frame rates with low preprocessing and rendering costs In this paper, we describe our technique and its implementation in detail. We also provide experimental evidence of its performance and briefly discuss extensions of our algorithm.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Polygon rendering, visibility ordering, occlusion culling", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-29, pages = "155--176", year = "1999", title = "Multicolor Combination Lemma", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-29", author = "Sariel Har-Peled", abstract = "We present an extension of the Combination Lemma of Guibas et al. (1983) that expresses the complexity of one or several faces in the overlay of many arrangements (as opposed to just two arrangements in (Guibas et al. 1989)), as a function of the number of arrangements, the number of faces, and the complexities of these faces in the separate arrangements. Several applications of the new Combination Lemma are presented. We first show that the complexity of a single face in an arrangement of k simple polygons with a total of n sides is $\Theta(n \alpha(k) )$, where $\alpha() is the inverse of Ackermann's function. We also give a new and simpler proof of the bound $ O(ROOT(m) \lambda_{s+2} (n))$ on the total number of edges of m faces in an arrangement of n Jordan arcs, each pair of which intersect in at most s points, where $\lambda_s(n)$ is the maximum length of a Davenport--Schinzel sequence of order s with n symbols. We extend this result, showing that the total number of edges of m faces in a sparse arrangement of n Jordan arcs is $ O( (n + ROOT(m)ROOT(w)) \lambda_{s+2} (n)/n ) , where w is the total complexity of the arrangement. Several other related results are also obtained.", month = apr, volume = "12", keywords = "Arrangements; Combination lemma", number = "3-4", journal = "Computational Geometry", } @InProceedings{EVL-1999-290, pages = "123--130", year = "1999", title = "Time-critical Multiresolution Scene Rendering", author = "Enrico Gobbetti and Eric Bouvier", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-290", abstract = "We describe a framework for time-critical rendering of graphics scenes composed of a large number of objects having complex geometric descriptions. Our technique relies upon a scene description in which objects are represented as multiresolution meshes. We perform a constrained optimization at each frame to choose the resolution of each potentially visible object that generates the best quality image while meeting timing constraints. The technique provides smooth level-of-detail control and aims at guaranteeing a uniform, bounded frame rate even for widely changing viewing conditions. The optimization algorithm is independent from the particular data structure used to represent multiresolution meshes. The only requirements are the ability to represent a mesh with an arbitrary number of triangles and to traverse a mesh structure at an arbitrary resolution in a short predictable time. A data structure satisfying these criteria is described and experimental results are discussed.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "multiresolution modeling, level of detail, adaptive rendering, time-critical graphics", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-291, pages = "131--138", year = "1999", title = "Skip Strips: Maintaining Triangle Strips for View-dependent Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-291", author = "Jihad A. El-Sana and Elvir Azanli and Amitabh Varshney", abstract = "View-dependent simplification has emerged as a powerful tool for graphics acceleration in visualization of complex environments. However, view-dependent simplification techniques have not been able to take full advantage of the underlying graphics hardware. Specifically, triangle strips are a widely used hardware-supported mechanism to compactly represent and efficiently render static triangle meshes. However, in a view-dependent framework, the triangle mesh connectivity changes at every frame making it difficult to use triangle strips. In this paper we present a novel data-structure, Skip Strip, that efficiently maintains triangle strips during such view-dependent changes. A Skip Strip stores the vertex hierarchy nodes in a skip-list-like manner with path compression. We anticipate that Skip Strips will provide a roadmap to combine rendering acceleration techniques for static datasets, typical of retained-mode graphics applications, with those for dynamic datasets found in immediate-mode applications.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-292, pages = "139--146", year = "1999", title = "Isosurface Extraction Techniques for Web-based Volume Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-292", author = "Klaus D. Engel and R{\"{u}}diger Westermann and Thomas Ertl", abstract = "The reconstruction of isosurfaces from scalar volume data has positioned itself as a fundamental visualization technique in many different applications. But the dramatically increasing size of volumetric data sets often prohibits the handling of these models on affordable low-end single processor architectures. Distributed client-server systems integrating high-bandwidth transmission channels and Web-based visualization tools are one alternative to attack this particular problem, but therefore new approaches to reduce the load of numerical processing and the number of generated primitives are required. In this paper we outline different scenarios for distributed isosurface reconstruction from large-scale volumetric data sets. We demonstrate how to directly generate stripped surface representations and we introduce adaptive and hierarchical concepts to minimize the number of vertices that have to be reconstructed, transmitted and rendered. Furthermore, we propose a novel computation scheme, which allows the user to flexibly exploit locally available resources. The proposed algorithms have been merged together in order to build a platform-independent Web-based application. Extensive use of VRML and Java OpenGL-bindings allows for the exploration of large-scale volume data quite efficiently.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Volume visualization, Isosurface reconstruction, Distributed Systems, Web-based Applications", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-293, pages = "147--154", year = "1999", title = "Isosurface Extraction in Time-varying Fields Using a Temporal Branch-on-Need Tree ({T}-{BON})", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-293", author = "Philip M. Sutton and Charles D. Hansen", abstract = "The Temporal Branch-on-Need Tree (T-BON) extends the three-dimensional branch-on-need octree for time-varying isosurface extraction. At each time step, only those portions of the tree and data necessary to construct the current isosurface are read from disk. This algorithm can thus exploit the temporal locality of the isosurface and, as a geometric technique, spatial locality between cells in order to improve performance. Experimental results demonstrate the performance gained and memory overhead saved using this technique.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "isosurface, time-dependent scalar field visualization, multiresolution methods, octree", booktitle = "EEE Visualization '99", } @InProceedings{EVL-1999-294, pages = "155--160", year = "1999", title = "Interactive Lens Visualization Techniques", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-294", author = "Christopher D. Shaw and James A. Hall and David S. Ebert and Aaron Roberts", abstract = "This paper describes new techniques for minimally immersive visualization of 3D scalar and vector fields, and visualization of document corpora. In our glyph-based visualization system, the user interacts with the 3D volume of glyphs using a pair of button-enhanced 3D position and orientation trackers. The user may also examine the volume using an interactive lens, which is a rectangle that slices through the 3Dvolume and displaysscalar information on its surface. Alens allows the display of scalar data in the 3Dvolume using a contour diagram, and a texture-based volume rendering.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Volumetric Data, Glyphs, Two-Handed Interfaces, Interactive Volume Rendering, Contour Diagrams, Stereoscopic Field Analyzer SFA, Seed Fill, Over Blending", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-295, pages = "169--174", year = "1999", title = "Exploring Geo-Scientific Data in Virtual Environments", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-295", author = "Bernd Fr{\"{o}}hlich and Stephen Barrass and Bj{\"{o}}rn Zehner and John Plate and Martin G{\"{o}}bel", abstract = "This paper describes tools and techniques for the exploration of geo-scientific data from the oil and gas domain in stereoscopic virtual environments. The two main sources of data in the exploration task are seismic volumes and multivariate well logs of physical properties down a bore hole. We have developed a props-based interaction device called the cubic mouse to allow more direct and intuitive interaction with a cubic seismic volume. This device effectively places the seismic cube in the user's hand. Geologists who have tried this device have been enthusiastic about the ease of use, and were adept only a few moments after picking it up. We have also developed a multi-modal visualisation and sonification technique for the dense, multivariate well log data. The visualisation can show two well log variables mapped along the well geometry in a bivariate colour scheme, and another variable on a sliding lens. A sonification probe is attached to the lens so that other variables can be heard. The sonification is based on a Geiger-counter metaphor that is widely understood and which makes it easy to explain. The data is sonified at higher or lower resolutions depending on the speed of the lens. Sweeps can be made at slower rates and over smaller intervals to home in on peaks, boundaries or other features in the full resolution data set.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-296, pages = "175--182", year = "1999", title = "Animating Wrinkles on Clothes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-296", author = "Sunil Hadap and Endre Bangarter and Pascal Volino and Nadia Magnenat-Thalmann", abstract = "This paper describes a method to simulate realistic wrinkles on clothes without fine mesh and large computational overheads. Cloth has very little in-plane deformations, as most of the deformations come from buckling. This can be looked at as area conservation property of cloth. The area conservation formulation of the method modulates the user defined wrinkle pattern, based on deformation of individual triangle. The methodology facilitates use of small in-plane deformation stiffnesses and a coarse mesh for the numerical simulation, this makes cloth simulation fast and robust. Moreover, the ability to design wrinkles (even on generalized deformable models) makes this method versatile for synthetic image generation. The method inspired from cloth wrinkling problem, being geometric in nature, can be extended to other wrinkling phenomena.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "cloth modeling, wrinkle modeling, deformable models", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-297, pages = "191--198", year = "1999", title = "Mixing Translucent Polygons with Volumes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-297", author = "Kevin A. Kreeger and Arie E. Kaufman", abstract = "We present an algorithm which renders opaque and/or translucent polygons embedded within volumetric data. The processing occurs such that all objects are composited in the correct order, by rendering thin slabs of the translucent polygons between volume slices using slice-order volume rendering. We implemented our algorithm with OpenGL on current general-purpose graphics systems. We discuss our system implementation, speed and image quality, as well as the renderings of several mixed scenes.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Mixing polygons and volumes, Translucent Polygon Rendering, Volume rendering, Ray casting, Voxelization", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-298, pages = "215--224", year = "1999", title = "A Distributed Graphics System for Large Tiled Displays", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-298", author = "Greg Humphreys and Pat Hanrahan", abstract = "Recent interest in large displays has led to renewed development of tiled displays, which are comprised of several individual displays arranged in an array and used as one large logical display. Stanford's 'Interactive Mural' is an example of such a display, using an overlapping four by two array of projectors that back-project onto a diffuse screen to form a 6' by 2' display area with a resolution of over 60 dpi. Writing software to make effective use of the large display space is a challenge because normal window system interaction metaphors break down. One promising approach is to switch to immersive applications; another approach, the one we are investigating, is to emulate office, conference room or studio environments which use the space to display a collection of visual material to support group activities. In this paper we describe a virtual graphics system that is designed to support multiple simultaneous rendering streams from both local and remote sites. The system abstracts the physical number of computers, graphics subsystems and projectors used to create the display. We provide performance measurements to show that the system scales well and thus supports a variety of different hardware configurations. The system is also interesting because it uses transparent 'layers,' instead of windows, to manage the screen", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99,", } @InProceedings{EVL-1999-299, pages = "199--206", year = "1999", title = "Multi-resolution Multi-field Ray Tracing: {A} mathematical overview", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-299", author = "Charidimos E. Gasparakis", abstract = "A rigorous mathematical review of ray tracing is presented. The concept of a generic voxel decoder acting on flexible voxel formats is introduced. The necessity of interpolating opacity weighted colors is proved, using a new definition of the blending process in terms of functional integrals. The continuum limit of the discrete opacity accumulation formula is presented, and its convexity properties are investigated. The issues pertaining to interpolation/ classification order are discussed. The lighting equation is expressed in terms of opacity weighted colors. The multi-resolution (along the ray) correction of the opacity-weighted color is derived. The mathematics of filtering on the image plane are studied, and an upper limit of the local pixel size on the image plane is obtained. Interpolation of pixel values on the image plane is shown to be inequivalent to blending of interpolated samples.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-3, pages = "1--16", year = "1999", title = "Software Visualization of {LR} Parsing and Synthesized Attribute Evaluation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-3", author = "Elizabeth L. White and Jeffrey Ruby and Laura Denise Deddens", language = "en", abstract = "Visual YACC is a tool that automatically creates visualizations of the YACC LR parsing process and synthesized attribute computation. The Visual YACC tool works by instrumenting a standard YACC grammar with graphics calls that draw the appropriate data structures given the current actions by the parser. The new grammar is processed by the YACC tools and the resulting parser displays the parse stack and parse tree for every step of the parsing process of a given input string. Visual YACC was initially designed to be used in compiler construction courses to supplement the teaching of parsing and syntax directed evaluation. We have also found it to be useful in the difficult task of debugging YACC grammars. In this paper, we describe this tool and how it is used in both contexts. We also detail two different implementations of this tool: one that produces a parser written in C with calls to Motif; and a second implementation that generates Java source code.", volume = "29", copyright = "John Wiley and Sons", number = "1", journal = "Software -- Practice and Experience", } @Article{EVL-1999-30, pages = "177--217", year = "1999", title = "The mixed volume optimization problem", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-30", author = "Mark J. Kaiser", abstract = "The mixed volume optimization problem is to determine the point of duality Q for a given convex set K that minimizes the {"}mixed volume{"} of the associated polar set $(K^* Q)$. In the plane, the mixed volumes translate as the area and length; in space, the mixed volumes include the volume, surface area, and mean width. In this paper, the geometric optimization problems associated with minimizing mixed volumes are examined from two perspectives: enumerative search and symbolic computation. The problem of minimizing the polar area through an enumerative search is first considered. The dual polygon $(Pm^* Q)$ is constructed for an arbitrary point of duality $Q \sin P_m^o$ by using an algebraic correspondence between the edges of Pm and the vertices of $(P_m^* Q)$ , and the area of $(P_m^* Q)$, A(P^*_m Q)$, is calculated and minimized using naive search techniques. A result due to Santal{\'{o}} is applied to verify the minimizing solution, and computational tests are described for various classes of randomly generated polygons. Statistical evidence indicates that a {"}good{"} approximation to the minimum area polar polygon occurs when the duality point is located at the center-of-gravity of Pm . The polar area problem is then investigated using symbolic procedures. Explicit symbolic expressions for the polar area and length functionals are computed and solved directly using the differential optimality conditions and Newton's iterative method of solution. The mixed volume and surface area functionals are formulated and solved using numerical products, and the mean width functional is described. Examples are used throughout to illustrate the methodology.", month = apr, volume = "12", keywords = "Mixed volumes; Geometric optimization; Constructive convex geometry; Symbolic computation; Polar figures; Santal{\'{o}} point", number = "3-4", journal = "Computational Geometry", } @InProceedings{EVL-1999-300, pages = "207--214", year = "1999", title = "Enabling Classification and Shading for 3{D} Texture Mapping based Volume Rendering using Open{GL} and Extensions", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-300", author = "Michael Mei{\ss{}}ner and Ulrich Hoffmann and Wolfgang Stra{\ss{}}er", abstract = "We present a new technique which enables direct volume rendering based on 3D texture mapping hardware, enabling shading as well as classification of the interpolated data. Our technique supports accurate lighting for a one directional light source, semi-transparent classification, and correct blending. To circumvent the limitations of one general classification, we introduce multiple classification spaces which are very valuable to understand the visualized data, and even mandatory to comprehensively grasp the 3D relationship of different materials present in the volumetric data. Furthermore, we illustrate how multiple classification spaces can be realized using existing graphics hardware. In contrast to previously reported algorithms, our technique is capable of performing all the above mentioned tasks within the graphics pipeline. Therefore, it is very efficient: The three dimensional texture needs to be stored only once and no load is put onto the CPU. Besides using standard OpenGL functionality, we exploit advanced per pixel operations and make use of available OpenGL extensions.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-301, pages = "225--232", year = "1999", title = "A Multi-Threaded Streaming Pipeline Architecture for Large Structured Data Sets", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-301", author = "C. Charles Law and Kenneth M. Martin and William J. Schroeder and Joshua Temkin", abstract = "Computer simulation and digital measuring systems are now generating data of unprecedented size. The size of data is becoming so large that conventional visualization tools are incapable of processing it, which is in turn is impacting the effectiveness of computational tools. In this paper we describe an object-oriented architecture that addresses this problem by automatically breaking data into pieces, and then processes the data piece-by-piece within a pipeline of filters. The piece size is user specified and can be controlled to eliminate the need for swapping (i.e., relying on virtual memory). In addition, because piece size can be controlled, any size problem can be run on any size computer, at the expense of extra computational time. Furthermore, pieces are automatically broken into sub-pieces and each piece assigned to a different thread for parallel processing. This paper includes numerical performance studies and references to the source code which is freely available on the Web.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-302, pages = "233--240", year = "1999", title = "Interactive Exploration of Volume Line Integral Convolution Based on 3{D}-Texture Mapping", author = "Christof Rezk-Salama and Peter Hastreiter and Teitzel Christian and Thomas Ertl", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-302", abstract = "Line integral convolution (LIC) is an effective technique for visualizing vector fields. The application of LIC to 3D flow fields has yet been limited by difficulties to efficiently display and animate the resulting 3D-images. Texture-based volume rendering allows interactive visualization and manipulation of 3D-LIC textures. In order to ensure the comprehensive and convenient exploration of flow fields, we suggest interactive functionality including transfer functions and different clipping mechanisms. Thereby, we efficiently substitute the calculation of LIC based on sparse noise textures and show the convenient visual access of interior structures. Further on, we introduce two approaches for animating static 3D-flow fields without the computational expense and the immense memory requirements for pre-computed 3D-textures and without loss of interactivity. This is achieved by using a single 3D-LIC texture and a set of time surfaces as clipping geometries. In our first approach we use the clipping geometry to pre-compute a special 3D-LIC texture that can be animated by time-dependent color tables. Our second approach uses time volumes to actually clip the 3D-LIC volume interactively during rasterization. Additionally, several examples demonstrate the value of our strategy in practice.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Flow Visualization, Animated LIC, Direct Volume Rendering, 3D-Textures Mapping, Interactive Volume Exploration", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-303, pages = "241--248", year = "1999", title = "A Framework for Assisted Exploration with Collaboration", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-303", author = "Eric A. Wernert and Andrew J. Hanson", abstract = "We approach the problem of exploring a virtual space by exploiting positional and camera-model constraints on navigation to provide extra assistance that focuses the user's explorational wanderings on the task objectives. Our specific design incorporates not only task-based constraints on the viewer's location, gaze, and viewing parameters, but also a personal 'guide' that serves two important functions: keeping the user oriented in the navigation space, and 'pointing' to interesting subject areas as they are approached. The guide's cues may be ignored by continuing in motion, but if the user stops, the gaze shifts automatically toward whatever the guide was interested in. This design has the serendipitous feature that it automatically incorporates a nested collaborative paradigm simply by allowing any given viewer to be seen as the 'guide' of one or more viewers following behind; the leading automated guide (we tend to select a guide dog for this avatar) can remind the leading live human guide of interesting sites to point out, while each real human collaborator down the chain has some choices about whether to follow the local leader's hints. We have chosen VRML as our initial development medium primarily because of its portability, and we have implemented a variety of natural modes for leading and collaborating, including ways for collaborators to attach to and detach from a particular leader.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "wayfinding, locomotion, navigation, exploration, collaboration, virtual reality, VRML", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-304, pages = "249--254", year = "1999", title = "Tensorlines: Advection-Diffusion based Propagation through Diffusion Tensor Fields", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-304", author = "David M. Weinstein and Gordon L. Kindlmann and Eric C. Lundberg", abstract = "Tracking linear features through tensor field datasets is an open research problem with widespread utility in medical and engineering disciplines. Existing tracking methods, which consider only the preferred local diffusion direction as they propagate, fail to accurately follow features as they enter regions of local complexity. This shortcoming is a result of partial voluming; that is, voxels in these regions often contain contributions from multiple features. These combined contributions result in ambiguities when deciding local primary feature orientation based solely on the preferred diffusion direction. In this paper, we introduce a novel feature extraction method, which we term tensorline propagation. Our method resolves the above ambiguity by incorporating information about the nearby orientation of the feature, as well as the anisotropic classification of the local tensor. The nearby orientation information is added in the spirit of an advection term in a standard diffusion-based propagation technique, and has the effect of stabilizing the tracking. To demonstrate the efficacy of tensorlines, we apply this method to the neuroscience problem of tracking white-matter bundles within the brain.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-305, pages = "255--262", year = "1999", title = "Visualizing Planar Vector Fields with Normal Component Using Line Integral Convolution", author = "Gerik Scheuermann and Holger Burbach and Hans Hagen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-305", abstract = "We present a method for visualizing three dimensional vector fields which are defined on a two dimensional manifold only. These vector fields do exist in real application, as we show by an example of an optical measuring instrument which can gauge the displacement at the surface of a mechanical part. The general idea is to compute LIC textures in the manifold's tangent space and to deform the manifold according to the normal information. The resulting LIC texture is mapped onto the deformed manifold and is rendered as a three dimensional scene. Due to the light's reflection on the deformed manifold, one can interactively explore the result of the deformation.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "LIC, vector field visualization, deformation", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-306, pages = "263--270", year = "1999", title = "The {"}Parallel Vectors{"} Operator - {A} Vector Field Visualization Primitive", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-306", author = "Ronald Peikert and Martin Roth", abstract = "In this paper we propose an elementary operation on a pair of vector fields as a building block for defining and computing global line-type features of vector or scalar fields. While usual feature definitions often are procedural and therefore implicit, our operator allows precise mathematical definitions. It can serve as a basis for comparing feature definitions and for reuse of algorithms and implementations. Applications focus on vortex core methods.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-307, pages = "271--278", year = "1999", title = "{C1}-Interpolation for Vector Field Topology Visualization", author = "Gerik Scheuermann and Xavier Tricoche and Hans Hagen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-307", abstract = "An application of C1 scalar interpolation for 2D vector field topology visualization is presented. Powell-Sabin and Nielson interpolants are considered which both make use of Nielson's Minimum Norm Network for the precomputation of the derivatives in our implementation. A comparison of their results to the commonly used linear interpolant underlines their significant improvement of singularity location and topological skeleton depiction. Evalution is based upon the processing of polynomial vector fields with known topology containing higher order singularities.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "vector field visualization, topology, critical point theory, C1-interpolation", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-308, pages = "279--284", year = "1999", title = "Optimal Triangular Haar Bases for Spherical Data", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-308", author = "Georges-Pierre Bonneau", abstract = "Multiresolution analysis based on FWT (Fast Wavelet Transform) is now widely used in Scientific Visualization. Spherical bi-orthogonal wavelets for spherical triangular grids where introduced in [5]. In order to improve on the orthogonality of the wavelets, the concept of nearly orthogonality, and two new piecewise-constant (Haar) bases were introduced in [4]. In our paper, we extend the results of [4]. First we give two one-parameter families of triangular Haar wavelet bases that are nearly orthogonal in the sense of [4]. Then we introduce a measure of orthogonality. This measure vanishes for orthogonal bases. Eventually, we show that we can find an optimal parameter of our wavelet families, for which the measure of orthogonality is minimized. Several numerical and visual examples for a spherical topographic data set illustrates our results.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "visualization, multiresolution, wavelets, orthogonality", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-309, pages = "285--290", year = "1999", title = "Cracking the Cracking Problem with Coons Patches", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-309", author = "Gregory M. Nielson and Dave Holliday and Tom Roxborough", abstract = "We present a new approach to solving the cracking problem. The cracking problem arises in many contexts in scientific visualization and computer graphics modeling where there is need for an approximation based upon domain decomposition that is fine in certain regions and coarse in others. This includes surface rendering, approximation of images and multiresolution terrain visualization. In general, algorithms based upon adaptive refinement strategies must deal with this problem. The new approach presented here is simple and general. It is based upon the use of a triangular Coons patch. Both the basic idea of using a triangular Coons patch in this context and the particular Coons patch that is used constitute the novel contributions of this paper.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-31, pages = "219--239", year = "1999", title = "On some geometric optimization problems in layered manufacturing", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-31", author = "Jayanth Majhi and Ravi Janardan and Michiel Smid and Prosenjit Gupta", abstract = "Efficient geometric algorithms are given for optimization problems arising in layered manufacturing, where a 3D object is built by slicing its CAD model into layers and manufacturing the layers successively. The problems considered include minimizing the stair-step error on the surfaces of the manufactured object under various formulations, minimizing the volume of the so-called support structures used, and minimizing the contact area between the supports and the manufactured object---all of which are factors that affect the speed and accuracy of the process. The stair-step minimization algorithm is valid for any polyhedron, while the support minimization algorithms are applicable only to convex polyhedra. The techniques used to obtain these results include construction and searching of certain arrangements on the sphere, 3D convex hulls, halfplane range searching, and constrained optimization.", month = apr, volume = "12", keywords = "Layered manufacturing; Computational geometry; Optimization", number = "3-4", journal = "Computational Geometry", } @InProceedings{EVL-1999-310, pages = "307--316", year = "1999", title = "Progressive Compression and Transmission of Arbitrary Triangular Meshes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-310", author = "Chandrajit L. Bajaj and Valerio Pascucci and Guozhong Zhuang", abstract = "The recent growth in the size and availability of large triangular surface models has generated interest in compact multi-resolution progressive representation and data transmission. An ongoing challenge is to design an efficient data structure that encompasses both compactness of geometric representations and visual quality of progressive representations. In this paper we introduce a topological layering based data-structure and an encoding scheme to build a compact progressive representation of an arbitrary triangular mesh (a 2D simplicial complex in 3D) with attached attribute data. This compact representation is composed of multiple levels of detail that can be progressively transmitted and displayed. The global topology, which is the number of holes and connected components, can be flexibly changed among successive levels while still achieving guaranteed size of the coarsest level mesh for very complex models. The flexibility in our encoding scheme also allows topology preserving progressivity.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-311, pages = "291--298", year = "1999", title = "{LOD}-Sprite Technique for Accelerated Terrain Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-311", author = "Baoquan Chen and J. Edward Swan II and Eddy Kuo and Arie E. Kaufman", abstract = "We present a new rendering technique, termed LOD-sprite rendering, which uses a combination of a level-of-detail (LOD) represen- tation of the scene together with reusing image sprites (previously rendered images). Our primary application is accelerating terrain rendering. The LOD-sprite technique renders an initial frame using a high-resolution model of the scene geometry. It renders subsequent frames with a much lower-resolution model of the scene geometry and texture-maps each polygon with the image sprite from the initial high-resolution frame. As it renders these subsequent frames the technique measures the error associated with the divergence of the view position from the position where the initial frame was rendered. Once this error exceeds a user-defined threshold, the technique re-renders the scene from the high-resolution model. We have efficiently implemented the LOD-sprite technique with texture-mapping graphics hardware. Although to date we have only applied LOD-sprite to terrain rendering, it could easily be extended to other applications. We feel LOD-sprite holds particular promise for real-time rendering systems.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-312, pages = "317--324", year = "1999", title = "Spiraling Edge: Fast Surface Reconstruction from Partially Organized Sample Points", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-312", author = "Patricia J. Crossno and Edward S. Angel", abstract = "Many applications produce three-dimensional points that must be further processed to generate a surface. Surface reconstruction algorithms that start with a set of unorganized points are extremely time-consuming. Sometimes, however, points are generated such that there is additional information available to the reconstruction algorithm. We present Spiraling Edge, a specialized algorithm for surface reconstruction that is three orders of magnitude faster than algorithms for the general case. In addition to sample point locations, our algorithm starts with normal information and knowledge of each point's neighbors. Our algorithm produces a localized approximation to the surface by creating a star-shaped triangulation between a point and a subset of its nearest neighbors. This surface patch is extended by locally triangulating each of the points along the edge of the patch. As each edge point is triangulated, it is removed from the edge and new edge points along the patch's edge are inserted in its place. The updated edge spirals out over the surface until the edge encounters a surface boundary and stops growing in that direction, or until the edge reduces to a small hole that is filled by the final triangle.", organization = "IEEE", address = "San Francisco", keywords = "Surface reconstruction, advancing front, triangulation", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-313, pages = "325--332", year = "1999", title = "Anisotropic Nonlinear Diffusion in Flow Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-313", author = "Tobias Preu{\ss{}}er and Martin Rumpf", abstract = "Vector field visualization is an important topic in scientific visualization. Its aim is to graphically represent field data in an intuitively understandable and precise way. Here a new approach based on anisotropic nonlinear diffusion is introduced. It enables an easy perception of flowdata and serves as an appropriate scale space method for the visualization of complicated flow pattern. The approach is closely related to nonlinear diffusion methods in image analysis where images are smoothed while still retaining and enhancing edges. Here an initial noisy image is smoothed along streamlines, whereas the image is sharpened in the orthogonal direction. The method is based on a continuous model and requires the solution of a parabolic PDE problem. It is discretized only in the final implementational step. Therefore, many important qualitative aspects can already be discussed on a continuous level. Applications are shown in 2D and 3D and the provisions for flow segmentation are outlined.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-314, pages = "299--306", year = "1999", title = "Implant Sprays: Compression of Progressive Tetrahedral Mesh Connectivity", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-314", author = "Renato B. Pajarola and Jarek Rossignac and Andrzej Szymczak", abstract = "Irregular tetrahedral meshes, which are popular in many engineering and scientific applications, often contain a large number of vertices. A mesh of V vertices and T tetrahedra requires 48*V bits or less to store the vertex coordinates, 4T log2 (V) bits to store the tetrahedra-vertex incidence relations, also called connectivity information, and k*V bits to store the k-bit value samples associated with the vertices. Given that T is 5 to 7 times larger than V and that V often exceeds 323 , the storage space required for the connectivity is larger than 300*V bits and thus dominates the overall storage cost. Our 'implants spray' compression approach introduced in this paper reduces this cost to about 30*V bits or less - a 10:1 compression ratio. Furthermore, implant spray supports the progressive refinement of a crude model through a series of vertex-splits operations.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "tetrahedral meshes, compression, multiresolution models, progressive incremental reconstruction", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-315, pages = "363--370", year = "1999", title = "Splatting Without The Blur", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-315", author = "Klaus Mueller and Torsten M{\"{o}}ller and Roger Crawfis", abstract = "Splatting is a volume rendering algorithm that combines efficient volume projection with a sparse data representation: Only voxels that have values inside the iso-range need to be considered, and these voxels can be projected via efficient rasterization schemes. In splatting, each projected voxel is represented as a radially symmetric interpolation kernel, equivalent to a fuzzy ball. Projecting such a basis function leaves a fuzzy impression, called a footprint or splat, on the screen. Splatting traditionally classifies and shades the voxels prior to projection, and thus each voxel foot-print is weighted by the assigned voxel color and opacity. Projecting these fuzzy color balls provides a uniform screen image for homogeneous object regions, but leads to a blurry appearance of object edges. The latter is clearly undesirable, especially when the view is zoomed on the object. In this work, we manipulate the rendering pipeline of splatting by performing the classification and shading process after the voxels have been projected onto the screen. In this way, volume contributions outside the iso-range never affect the image. Since shading requires gradients, we not only splat the density volume, using regular splats, but we also project the gradient volume, using gradient splats. However, alternative to gradient splats, we can also compute the gradients on the projection plane, using central differencing. This latter scheme cuts the number of footprint rasterization by a factor of four, since only the voxel densities have to be projected. Our new method renders objects with crisp edges and well-preserved surface detail. Added overhead is the calculation of the screen gradients and the per-pixel shading. Both of these operations, however, may be performed using fast techniques employing lookup tables", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-316, pages = "333--340", year = "1999", title = "Visualizing Multivalued Data from 2{D} Incompressible Flows Using Concepts from Painting", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-316", author = "R. M. Kirby and H. Marmanis and David H. Laidlaw", abstract = "We present a new visualization method for 2d flows which allows us to combine multiple data values in an image for simultaneous viewing. We utilize concepts from oil painting, art, and design as introduced in [1] to examine problems within fluid mechanics. We use a combination of discrete and continuous visual elements arranged in multiple layers to visually represent the data. The representations are inspired by the brush strokes artists apply in layers to create an oil painting. We display commonly visualized quantities such as velocity and vorticity together with three additional mathematically derived quantities: the rate of strain tensor (defined in section 4), and the turbulent charge and turbulent current (defined in section 5). We describe the motivation for simultaneously examining these quantities and use the motivation to guide our choice of visual representation for each particular quantity. We present visualizations of three flow examples and observations concerning some of the physical relationships made apparent by the simultaneous display technique that we employed", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-317, pages = "341--348", year = "1999", title = "{PLIC}: Bridging the Gap Between Streamlines and {LIC}", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-317", author = "Vivek Verma and David Kao and Alex Pang", abstract = "This paper explores mapping strategies for generating LIC-like images from streamlines and streamline-like images from LIC. The main contribution of this paper is a technique which we call pseudo-LIC or PLIC. By adjusting a small set of key parameters, PLIC can generate flow visualizations that span the spectrum of streamline-like to LIC-like images. Among the advantages of PLIC are: image quality comparable with LIC, performance speedup over LIC, use of a template texture that is independent of the size of the flow field, handles the problem of multiple streamlines occupying the same pixel in image space, reduced aliasing, applicability to time varying data sets, and variable speed animation.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "unsteady flow, variable speed animation, jitter, texture mapping, comparative visualization", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-318, pages = "349--354", year = "1999", title = "Collapsing Flow Topology Using Area Metrics", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-318", author = "Wim C. de Leeuw and Robert van Liere", abstract = "Visualization of topological information of a vector field can provide useful information on the structure of the field. However, in turbulent flows standard critical point visualization will result in a cluttered image which is difficult to interpret. This paper presents a technique for collapsing topologies. The governing idea is to classify the importance of the critical points in the topology. By only displaying the more important critical points, a simplified depiction of the topology can be provided. Flow consistency is maintained when collapsing the topology, resulting in a visualization which is consistent with the original topology. We apply the collapsing topology technique to a turbulent flow field.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "multi-level visualization techniques, flow visualization, flow topology", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-319, pages = "355--362", year = "1999", title = "Multiresolution Techniques for Interactive Texture-based Volume Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-319", author = "Eric C. LaMar and Bernd Hamann and Kenneth I. Joy", abstract = "We present a multiresolution technique for interactive texture-based volume visualization of very large data sets. This method uses an adaptive scheme that renders the volume in a region-of-interest at a high resolution and the volume away from this region at progressively lower resolutions. The algorithm is based on the segmentation of texture space into an octree, where the leaves of the tree define the original data and the internal nodes define lower-resolution versions. Rendering is done adaptively by selecting high-resolution cells close to a center of attention and low-resolution cells away from this area. We limit the artifacts introduced by this method by modifying the transfer functions in the lower-resolution data sets and utilizing spherical shells as a proxy geometry. It is possible to use this technique to produce viewpoint-dependent renderings of very large data sets.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "multiresolution rendering, volume visualization, hardware texture", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-32, pages = "63--83", year = "1999", title = "Fast randomized point location without preprocessing in two- and three-dimensional Delaunay triangulations", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-32", author = "Ernst P. M{\"u}cke and Isaac Saias and Binhai Zhu", abstract = "This paper studies the point location problem in Delaunay triangulations without preprocessing and additional storage. The proposed procedure finds the query point by simply {"}walking through{"} the triangulation, after selecting a {"}good starting point{"} by random sampling. The analysis generalizes and extends a recent result for d=2 dimensions by proving this procedure takes expected time close to $O(n^{1/(d+1)}) for point location in Delaunay triangulations of n random points in d=3 dimensions. Empirical results in both two and three dimensions show that this procedure is efficient in practice.", month = feb, volume = "12", keywords = "Computational geometry; Geometric computing; Randomized algorithms; Delaunay triangulations; Point location; Three dimensional", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-320, pages = "371--378", year = "1999", title = "A Fast Volume Rendering Algorithm for Time-Varying Fields Using a Time-Space Partitioning ({TSP}) Tree", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-320", author = "Han-Wei Shen and Ling-Jan Chiang and Kwan-Liu Ma", abstract = "This paper presents a fast volume rendering algorithm for time-varying fields. We propose a new data structure, called Time-Space Partitioning (TSP) tree, that can effectively capture both the spatial and the temporal coherence from a time-varying field. Using the proposed data structure, the rendering speed is substantially improved. In addition, our data structure helps to maintain the memory access locality and to provide the sparse data traversal so that our algorithm becomes suitable for large-scale out-of-core applications. Finally, our algorithm allows flexible error control for both the temporal and the spatial coherence so that a trade-off between image quality and rendering speed is possible. We demonstrate the utility and speed of our algorithm with data from several time-varying CFD simulations. Our rendering algorithm can achieve substantial speedup while the storage space overhead for the TSP tree is kept at a minimum.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "scalar field visualization, volume visualization, volume rendering, time-varying fields", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-321, pages = "379--388", year = "1999", title = "High Performance Presence-Accelerated Ray Casting", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-321", author = "Ming Wan and Arie E. Kaufman and Steve Bryson", abstract = "We present a novel presence acceleration for volumetric ray casting. A highly accurate estimation for object presence is obtained by projecting all grid cells associated with the object boundary on the image plane. Memory space and access time are reduced by run-length encoding of the boundary cells, while boundary cell projection time is reduced by exploiting projection templates and multiresolution volumes. Efforts have also been made towards a fast perspective projection as well as interactive classification. We further present task partitioning schemes for effective parallelization of both boundary cell projection and ray traversal procedures. Good load balancing has been reached by taking full advantage of both the optimizations in the serial rendering algorithm and shared-memory architecture. Our experimental results on a 16-processor SGI Power Challenge have shown interactive rendering rates for 2563/sup> volumetric data sets at 10 - 30 Hz. This paper describes the theory and implementation of our algorithm, and shows its superiority over the shear-warp factorization approach.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Volume rendering, presence acceleration, run-length encoding, projection template, multiresolution volumes, interactive classification, parallel processing", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-322, pages = "393--396", year = "1999", title = "Digital Design of a Surgical Simulator for Interventional Magnetic Resonance Imaging", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-322", author = "Terry S. Yoo and Penny Rheingans", abstract = "We present the design of a simulator for a prototype interventional magnetic resonance imaging scanner. This MRI scanner is integrated with an operating theater, enabling new techniques in minimally invasive surgery. The simulator is designed with a threefold purpose: (1) to provide a rehearsal apparatus for practicing and modifying conventional procedures for use in the magnetic environment, (2) to serve as a visualization workstation for procedure planning and previewing as well as a post-operative review, and (3) to form the foundation of a laboratory workbench for the development of new surgical tools and procedures for minimally invasive surgery. The simulator incorporates pre-operative data, either MRI or CT exams, as well as data from commercial surgical planning systems. Dynamic control of the simulation and interactive display of preoperative data in lieu of intra-operative data is handled via an opto-electronic tracking system. The resulting system is contributing insights into how best to perform visualization for this new surgical environment.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-323, pages = "397--400", year = "1999", title = "Volume Rendering Based Interactive Navigation within the Human Colon", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-323", author = "Ming Wan and Qingyu Tang and Arie E. Kaufman and Zhengrong Liang and Mark Wax", abstract = "We present an interactive navigation system for virtual colonoscopy, which is based solely on high performance volume rendering. Previous colonic navigation systems have employed either a surface rendering or a Z-buffer-assisted volume rendering method that depends on the surface rendering results. Our method is a fast direct volume rendering technique that exploits distance information stored in the potential field of the camera control model, and is parallelized on a multiprocessor. Experiments have been conducted on both a simulated pipe and patients' data sets acquired with a CT scanner.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-324, pages = "401--404", year = "1999", title = "A Computer Animation Representing the Molecular Events of {G} protein-coupled Receptor Activation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-324", author = "Zoya Maslak and Douglas J. Steel and Robert J. McDermott", abstract = "The molecular events involved in the activation of G protein-coupled receptors, represent a fundamental biochemical process. These events were selected for animation because the mechanism involves both a ligand-receptor conformational shape change, and an enzyme-substrate conformational shape change. Expository animation brought this biochemical process to life.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-325, pages = "405--408", year = "1999", title = "Visualizing Gridded Datasets with Large Number of Missing Values", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-325", author = "Suzana Djurcilov and Alex Pang", abstract = "Much of the research in scientific visualization has focused on complete sets of gridded data. This paper presents our experience dealing with gridded data sets with large number of missing or invalid data, and some of our experiments in addressing the shortcomings of standard off-the-shelf visualization algorithms. In particular, we discuss the options in modifying known algorithms to adjust to the specifics of sparse datasets, and provide a new technique to smooth out the side-effects of the operations. We apply our findings to data acquired from NEXRAD (NEXt generation RADars) weather radars, which usually have no more than 3 to 4 percent of all possible cell points filled.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "curvilinear grid, sparse data visualization, Delauney triangulation, isosurface, NEXRAD", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-326, pages = "389--392", year = "1999", title = "Interactive Exploration of Extra- and Interacranial Blood Vessels", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-326", author = "Dirk Bartz and Wolfgang Stra{\ss{}}er and Martin Skalej and Dorothea Welte", abstract = "We present a system for interactive explorations of extra-and intracranial blood vessels. Starting with a stack of images from 3D angiography, we use virtual clips to limit the segmentation of the vessel tree to the parts the neuroradiologists are interested in. Furthermore, methods of interactive virtual endoscopy are applied in order to provide an interior view of the blood vessels", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Virtual Environments, 3D Angiography, Virtual Angioscopy, Interventional Neuroradiology, Selective Segmentation, Computer Assisted Diagnosis", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-328, pages = "409--412", year = "1999", title = "Detecting Vortical Phenomena in Vector Data by Medium-Scale Correlation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-328", author = "H.-G. Pagendarm and B. Henne and M. Rutten", abstract = "The detection of vortical phenomena in vector data is one of the key issues in many technical applications, in particular in flow visualization. Many existing approaches rely on purely local evaluation of the vector data. In order to overcome the limits of a local approach we choose to combine a local method with a correlation of a pre-defined generic vortex with the data in a medium-scale region. Two different concepts of a generic vortices were tested on various sets of flow velocity vector data. The approach is not limited to the two generic patterns suggested here. The method was found to successfully detect vortices in cases were other methods fail.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-329, pages = "417--420", year = "1999", title = "Visual Debugging of Visualization Software: {A} Case Study for Particle Systems", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-329", author = "Patricia J. Crossno and Edward S. Angel", abstract = "Visualization systems are complex dynamic software systems. Debugging such systems is difficult using conventional debuggers because the programmer must try to imagine the three-dimensional geometry based on a list of positions and attributes. In addition, the programmer must be able to mentally animate changes in those positions and attributes to grasp dynamic behaviors within the algorithm. In this paper we shall show that representing geometry, attributes, and relationships graphically permits visual pattern recognition skills to be applied to the debugging problem. The particular application is a particle system used for isosurface extraction from volumetric data. Coloring particles based on individual attributes is especially helpful when these colorings are viewed as animations over successive iterations in the program. Although we describe a particular application, the types of tools that we discuss can be applied to a variety of problems", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Visual debugging, algorithm animation, program animation, program visualization, particle systems", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-33, pages = "85--103", year = "1999", title = "Checking geometric programs or verification of geometric structures", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-33", author = "Kurt Mehlhorn and Stefan N{\"a}her and Michael Seel and Raimund Seidel and Thomas Schilz and Stefan Schirra and Christian Uhrig", abstract = "A program checker verifies that a particular program execution is correct. We give simple and efficient program checkers for some basic geometric tasks. We report about our experiences with program checking in the context of the LEDA system. We discuss program checking for data structures that have to rely on user-provided functions.", month = feb, volume = "12", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-330, pages = "413--416", year = "1999", title = "Interactive Visualization of Fluid Dynamics Simulations in Locally Refined Cartesian Grids", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-330", author = "Martin Schultz and Frank Recks and Wolf Bartelheimer and Thomas Ertl", abstract = "This work presents interactive flow visualization techniques specifically adapted for PowerFLOW(tm), a lattice-based CFD code from the EXA corporation. Their Digital Physics(tm) fluid simulation technique is performed on a hierarchy of locally refined cartesian grids with a fine voxel resolution in areas of interesting flow features. Among other applications the PowerFLOW solver is used for aerodynamic simulations in car body development where the advantages of automatic grid generation from CAD models is of great interest. In a joint project with BMW and EXA we are developing a visualization tool which incorporates virtual reality techniques for the interactive exploration of the large scalar and vector data sets. In this paper we describe the specific data structures and interpolation techniques and we report on fast particle tracing taking into account collisions with the car body geometry. An OpenGL Optimizer based implementation allows for the inspection of the flow with particle probes and slice probes at interactive frame rates.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-333, pages = "421--424", year = "1999", title = "{DELTA}'s Virtual Physics Laboratory {A} Comprehensive Learning Platform on Physics & Astronomy", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-333", author = "Sepideh Chakaveh and Udo Zlender and Detlef Skaley and Konstantinos Fostiropoulos and Dieter Breitschwerdt", abstract = "Perhaps the most effective instrument to simplify and to clarify the comprehension of any complex mathematical or scientific theory is through visualisation. Moreover using interactivity & 3D real time representations, one can easily explore and hence learn quickly in the virtual environments. The concept of virtual and safe laboratories has vast potentials in education. With the aid of computer simulations & 3D visualisations, many dangerous or cumbersome experiments may be implemented in the virtual environments, with rather small effort. Nonetheless visualisation alone is of little use if the respective simulation is not scientifically accurate. Hence a rigours combination of precise computation as well as sophisticated visualisation, presented through some intuitive user interface is required to realise a virtual laboratory for education. Here we introduce Delta's Virtual Physics Laboratory, comprising of a wide range of applications in the field of Physics & Astronomy, which can be implemented and used as an interactive learning tool on the World Wide Web.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-334, pages = "433--436", year = "1999", title = "Visualization of Conflicts and Resolutions in a {"}Free Flight{"} Scenario", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-334", author = "Ronald Azuma and Howard Neely III and Mike Daily and Mario Correa", abstract = "'Free Flight' will change todays air traffic control system by giving pilots increased flexibility to choose and modify their routes in real time, reducing costs and increasing system capacity. This increased flexibility comes at the price of increased complexity. If Free Flight is to become a reality, future air traffic controllers, pilots, and airline managers will require new conflict detection, resolution and visualization decision support tools. This paper describes a testbed system for building and evaluating such tools, including its current capabilities, lessons we learned, and feedback received from expert users. The visualization system provides an overall plan view supplemented with a detailed perspective view, allowing a user to examine highlighted conflicts and select from a list of proposed solutions, as the scenario runs in real time. Future steps needed to improve this system are described.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "air traffic control, collision detection, aircraft, decision support tools, interactive 3D graphics", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-335, pages = "425--428", year = "1999", title = "VizCraft: {A} Multidimensional Visualization Tool for Aircraft Configuration Design", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-335", author = "A. Goel and C. Baker and C. A. Shaffer and B. Grossman and R. T. Haftka and W. H. Mason and L. T. Watson", abstract = "We describe a visualization tool to aid aircraft designers during the conceptual design stage. The conceptual design for an aircraft is defined by a vector of 10-30 parameters. The goal is to find a vector that minimizes an objective function while meeting a series of constraints. VizCraft integrates the simulation code that evaluates the design with visualizations for analyzing the design individually or in contrast to other designs. VizCraft allows the designer to easily switch between the view of a design in the form of a parameter set, and a visualization of the corresponding aircraft. The user can easily see which, if any, constraints are violated. VizCraft also allows the user to view a database of designs using parallel coordinates.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Scientific data visualization, aircraft design, multidisciplinary design optimization, multidimensional visualization", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-336, pages = "429--432", year = "1999", title = "Design and Implementation of an Immersive Geoscience Toolkit", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-336", author = "Christophe Winkler and Fabien Bosquet and Xavier Cavin and Jean-Claude Paul", abstract = "Having a better way to represent and to interact with large geological models are topics of high interest in geoscience, and especially for oil and gas companies. We present in this paper the design and implementation of a visualization program that involves two main features. It is based on the central data model, in order to display in real time the modifications caused by the modeler. Furthermore, it benefits from the different immersive environments which give the user a much more accurate insight of the model than a regular computer screen. Then, we focus on the difficulties that come in the way of performance.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-337, pages = "437--440", year = "1999", title = "Real-Time Visualization of Scalably Large Collections of Heterogeneous Objects", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-337", author = "Douglass Davis and William Ribarsky and T. Y. Jiang and Nickolas Faust and Sean Ho", abstract = "This paper presents results for real-time visualization of out-of-core collections of 3D objects. This is a significant extension of previous methods and shows the generality of hierarchical paging procedures applied both to global terrain and any objects that reside on it. Applied to buildings, the procedure shows the effectiveness of using a screen-based paging and display criterion within a hierarchical framework. The results demonstrate that the method is scalable since it is able to handle multiple collections of buildings (e.g., cities) placed around the earth with full interactivity and without extensive memory load. Further the method shows efficient handling of culling and is applicable to larger, extended collections of buildings. Finally, the method shows that levels of detail can be incorporated to provide improved detail management.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-338, pages = "441--444", year = "1999", title = "Geo-Spatial Visualization for Situational Awareness", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-338", author = "Eliot Feibush and Nikhil Gagvani and Daniel Williams", abstract = "Situational awareness applications require a highly detailed geo-spatial visualization covering a large geographic area. Conventional polygon based terrain modeling would exceed the capacity of current computer rendering. Terrain visualization techniques for a situational awareness application are described in this case study. Visualizing large amounts of terrain data has been achieved using very large texture maps. Sun shading is applied to the terrain texture map to enhance perception of relief features. Perception of submarine positions has been enhanced using a translucent, textured water surface. Each visualization technique is illustrated in the accompanying video tape.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-339, pages = "445--448", year = "1999", title = "{"}Whole Field Modelling{"} - Effective Real-time and Post-survey Visualization of Underwater Pipelines", author = "Paul Chapman and Derek Wills and Peter Stevens and Graham Brookes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-339", abstract = "The detailed underwater bathymetric data provided by Sonar Research and Development's high speed multi-frequency sonar transducer system provides new challenges in the development of interactive seabed visualizing tools. This paper introduces a 'Whole Field Modelling' system developed at Sonar Research and Development Ltd and The Department of Computer Science, University of Hull. This system provides the viewer with a new 3D underwater visualization environment that allows the user to pilot a virtual underwater vehicle around an accurate seabed model. In this paper we consider two example case studies that use the Whole Field Modelling System for visualizing sonar data. Both case studies, visualizing real-time pipeline dredging and pipe restoration visualization, are implemented using real survey data.", organization = "IEEE", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @Article{EVL-1999-34, pages = "105--124", year = "1999", title = "Temporally coherent conservative visibility", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-34", author = "Satyan Coorg and Seth Teller", abstract = "Efficiently identifying polygons that are visible from a changing synthetic viewpoint is an important problem in computer graphics. Even with hardware support, simple algorithms like depth-buffering cannot achieve interactive frame rates when applied to geometric models with many polygons. However, a visibility algorithm that exploits the occlusion properties of the scene to identify a superset of visible polygons, without touching most invisible polygons, could achieve fast frame rates while viewing such models. In this paper, we present a new approach to the visibility problem. The novel aspects of our algorithm are that it is temporally coherent and conservative; for all viewpoints the algorithm overestimates the set of visible polygons. As the synthetic viewpoint moves, the algorithm reuses visibility information computed for previous viewpoints. It does so by computing visual events at which visibility changes occur, and efficiently identifying and discarding these events as the viewpoint changes. In essence, the algorithm implicitly constructs and maintains a linearized portion of an aspect graph, a data structure for representing visual events. We demonstrate that the visibility algorithm significantly accelerates rendering of several test models.", month = feb, volume = "12", keywords = "Conservative visibility; Temporal coherence; Hierarchical representations; kD-trees; Visual events; Linearized dynamic aspect graphs", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-340, pages = "449--452", year = "1999", title = "Visualizing the Evolution of a Subject Domain: {A} Case Study", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-340", author = "Chaomei Chen and Leslie Carr", abstract = "We explore the potential of information visualization techniques in enhancing existing methodologies for domain analysis and modeling. In this case study, we particularly focus on visualizing the evolution of the hypertext field based on author co-citation patterns, including the use of a sliding-window scheme to generate a series of annual snapshots of the domain structure, and a factor-referenced color-coding scheme to highlight predominant specialties in the field.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "applications of visualization, domain analysis, citation analysis, visualization of literature", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-341, pages = "453--456", year = "1999", title = "An Interactive Framework for Visualizing Foreign Currency Exchange Options", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-341", author = "D. L. Gresh and B. E. Rogowitz and M. S. Tignor and E. J. Maryland", abstract = "Analyzing options is a complex, multi-variate process. Option behavior depends on a variety of market conditions which vary over the time course of the option. The goal of this project is to provide an interactive visual environment which allows the analyst to explore these complex interactions, and to select and construct specific views for communicating information to non-analysts (e.g., marketing managers and customers). In this paper we describe an environment for exploring 2- and 3-dimensional representations of options data, dynamically varying parameters, examining how multi-variate relationships develop over time, and exploring the likelihood of the development of different outcomes over the life of the option. We also demonstrate how this tool has been used by analysts to communicate to non-analysts how particular options no longer deliver the behavior they were originally intended to provide.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "visualization, foreign currency options, interactive applications", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-342, pages = "457--462", year = "1999", title = "Visualizing Large-Scale Telecommunication Networks and Services", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-342", author = "Eleftherios E. Koutsofios and Stephen C. North and Russell Truscott and Daniel A. Keim", abstract = "Visual exploration of massive data sets arising from telecommunication networks and services is a challenge. This paper describes SWIFT-3D, an integrated data visualization and exploration system created at AT&T Labs for large scale network analysis. SWIFT-3D integrates a collection of interactive tools that includes pixel-oriented 2D maps, interactive 3D maps, statistical displays, network topology diagrams and an interactive drill-down query interface. Example applications are described, demonstrating a successful application to analyze unexpected network events (high volumes of unanswered calls), and comparison of usage of an Internet service with voice network traffic and local access coverage.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-343, pages = "463--466", year = "1999", title = "Detecting Null Alleles with Vasarely Charts", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-343", author = "Carl Manaster and Elizabeth Nanthakumar and Phillip Morin", abstract = "Microsatellite genotypes can have problems that are difficult to detect with existing tools. One such problem is null alleles. This paper presents a new visualization tool that helps to find and characterize these errors. The paper explains how the tool is used to analyze groups of genotypes and proposes other possible uses.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Visualization, null alleles, Vasarely chart", booktitle = "EEE Visualization '99", } @InProceedings{EVL-1999-344, pages = "467--470", year = "1999", title = "Automating Transfer Function Design for Comprehensible Volume Rendering Based on 3{D} Field Topology Analysis", author = "Issei Fujishiro and Taeko Azuma and Yuriko Takeshima", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-344", abstract = "This paper describes initial results of a 3D field topology analysis for automating transfer function design aiming at comprehensible volume rendering. The conventional Reeb graph-based approach to describing topological features of 3D surfaces is extended to capture the topological skeleton of a volumetric field. Based on the analysis result, which is represented in the form of a hyper Reeb graph, a procedure is proposed for designing appropriate color/opacity transfer functions. Two analytic volume datasets are used to preliminarily prove the feasibility of the present design methodology.", organization = "IEEE", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Volume visualization, direct volume ren-dering, comprehensible rendering, transfer function, isosurface, Reeb graph, critical surfac", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-345, pages = "471--474", year = "1999", title = "Accelerating 3{D} Convolution using Graphics Hardware", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-345", author = "Matthias Hopf and Thomas Ertl", abstract = "Many volume filtering operations used for image enhancement, data processing or feature detection can be written in terms of three-dimensional convolutions. It is not possible to yield interactive frame rates on todays hardware when applying such convolutions on volume data using software filter routines. As modern graphics workstations have the ability to render two-dimensional convoluted images to the frame buffer, this feature can be used to accelerate the process significantly. This way generic 3D convolution can be added as a powerful tool in interactive volume visualization toolkits.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Convolution, Hardware Acceleration, Volume Visualization", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-346, pages = "475--478", year = "1999", title = "Visualizing Simulated Room Fires", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-346", author = "Jayesh Govindarajan and Matthew Ward and Jonathan Barnett", abstract = "Recent advances in fire science and computer modeling of fires allow scientists to predict fire growth and spread through structures. In this paper we describe a variety of visualizations of simulated room fires for use by both fire protection engineers and fire suppression personnel. We also introduce the concept of fuzzy visualization, which results from the superposition of data from several separate simulations into a single visualization.", organization = "IEEE", address = "San Francisco", editor = "David Ebert and Markus Gross and Bernd Hamann", keywords = "Scientific visualization, simulation, fire modeling", booktitle = "IEEE Visualization '99", } @InProceedings{EVL-1999-347, pages = "1--12", year = "1999", title = "Interactive Line Art Rendering of FreeformSurfaces", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-347", author = "Gershon Elber", abstract = "In recent years, synthetically created line art renderings have reached quality levels that are aesthetically pleasing. Moreover, the sketch based approach was found to be quite capable at conveying geometrical information in an intuitive manner. While a growing interest in this type of rendering method has yielded successful and appealing results, the developed techniques were, for the most part, too slow to be embedded in real time interactive display. This paper presents a line art rendering method for freeform polynomial and rational surfaces that is capable of achieving real time and interactive display. A careful preprocessing stage that combines an a-priori construction of line art strokes with proper classification of these strokes, allows one to significantly alleviate the computational cost, in real time, of the sketch based rendering, and enables interactive line art display.", editor = "P. Brunet and R. Scopigno", keywords = "Illustrations, Line Art Drawings, Freeform Surfaces, NURBS, Surface Coverage, Real Time, Interaction.", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-348, pages = "13--22", year = "1999", title = "Comprehensive Halftoning of 3{D} Scenes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-348", author = "O. Veryovka and J. Buchanan", abstract = "The display of images on binary output hardware requires a halftoning step. Conventional halftoning algorithms approximate image values independently from the image content and often introduce artificial texture that obscures fine details. The objective of this research is to adapt a halftoning technique to 3D scene information and thus to enhance the display of computer generated 3D scenes. Our approach is based on the control of halftoning texture by the combination of ordered dithering and error diffusion techniques. We extend our previous work and enable a user to specify the shape, scale, direction, and contrast of the halftoning texture using an external buffer. We control texture shape by constructing a dither matrix from an arbitrary image or a procedural texture. Texture direction and scale are adapted to the external information by the mapping function. Texture contrast and the accuracy of tone reproduction are varied across the image using the error diffusion process. We halftone images of 3D scenes by using the geometry, position, and illumination information to control the halftoning texture. Thus, the texture provides visual cues and can be used to enhance the viewer's comprehension of the display.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", keywords = "Illustrations, Line Art Drawings, Freeform Surfaces, NURBS, Surface Coverage, Real Time, Interaction.", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-349, pages = "23--30", year = "1999", title = "An Efficient and Flexible Perception Pipeline for Autonomous Agents", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-349", author = "Christophe Bordeux and Ronan Boulic and Daniel Thalmann", abstract = "Agents in virtual environments require a combination of perception and action to behave in an autonomous way. We extend a software architecture for the management of actions blending, called AGENTlib, with a perception mechanism. The perception system provides a uniform interface to various techniques in the field of virtual perception, including synthetic vision, database access and perception persistency. We describe the framework we designed to efficiently filter valuable information from the scene and we address concerns about computation redundancy and data propagation through multiple filtering modules.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @Article{EVL-1999-35, pages = "125--152", year = "1999", title = "Visualizing geometric algorithms over the Web", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-35", author = "James E. Baker and Isabel F. Cruz and Giuseppe Liotta and Roberto Tamassia", abstract = "The visual nature of geometry applications makes them a natural area where visualization can be an effective tool for demonstrating algorithms. In this paper we propose a new model, called Mocha, for interactive visualization of algorithms over the World Wide Web. Mocha is a distributed model with a client-server architecture that optimally partitions the software components of a typical algorithm execution and visualization system, and leverages the power of the Java language, which has become the standard for distributing interactive platform-independent applications across the Web. Mocha provides high levels of security, protects the algorithm code, places a light communication load on the Internet, and allows users with limited computing resources to access executions of computationally expensive algorithms. The user interface combines fast responsiveness with the powerful authoring capabilities of hypertext narratives. We describe the architecture of Mocha, show its advantages over previous methods, and present a prototype that can be accessed by any user with a Java-enabled Web browser. The Mocha prototype has been widely accessed over the Web, as demonstrated by the statistics that we have collected, and the Mocha model has been adopted by other research groups. Mocha is currently part of a broader system, called GeomNet, which performs distributed geometric computing over the Internet.", month = feb, volume = "12", keywords = "Geometric algorithm visualization; World Wide Web; Client-server architecture; Visual interface; Java; Multimedia", number = "1-2", journal = "Computational Geometry", } @InProceedings{EVL-1999-350, pages = "31--38", year = "1999", title = "Interactive Cuts through 3-Dimensional Soft Tissue", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-350", author = "Daniel Bielser and Volker A. Maiwald and Markus H. Gross", abstract = "We describe a physically based framework for interactive modeling and cutting of 3-dimensional soft tissue that can be used for surgery simulation. Unlike existing approaches which are mostly designed for tensorproduct grids our methods operate on tetrahedral decompositions giving more topological and geometric flexibility for the efficient modeling of complex anatomical structures. We start from an initial tetrahedralization such as being provided by any conventional meshing method. In order to track topological changes tetrahedra intersected by the virtual scalpel are split into substructures whose connectivity follows the trajectory of the cut, which can be arbitrary. For the efficient computation of collisions between the scalpel and individual tetrahedra we devised a local collision detection algorithm. The underlying physics is approximated through masses and springs attached to each tetrahedral vertex and edge. A hierarchical Runge-Kutta iteration computes the relaxation of the system by traversing the designed data structures in a breadth-first order. The framework includes a force-feedback interface and uses real-time texture mapping to enhance the visual realism.", editor = "P. Brunet and R. Scopigno", keywords = "Physically Based Modeling, Surgery Simulation, Soft Tissue, Tetrahedralization, Interactive Cut, Virtual Scalpel, Runge-Kutta Method", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-351, pages = "39--50", year = "1999", title = "Creating Architectural Models from Images", author = "David Liebowitz and Antonio Criminisi and Andrew Zisserman", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-351", abstract = "We present methods for creating 3D graphical models of scenes from a limited numbers of images, i.e. one or two, in situations where no scene co-ordinate measurements are available. The methods employ constraints available from geometric relationships that are common in architectural scenes - such as parallelism and orthogonality - together with constraints available from the camera. In particular, by using the circular points of a plane simple, linear algorithms are given for computing plane rectification, plane orientation and camera calibration from a single image. Examples of image based 3D modelling are given for both single images and image pairs.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-352, pages = "51--60", year = "1999", title = "Occluder Shadows for Fast Walkthroughs of Urban Environments", author = "Peter Wonka and Dieter Schmalstieg", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-352", abstract = "This paper describes a new algorithm that employs image-based rendering for fast occlusion culling in complex urban environments. It exploits graphics hardware to render and automatically combine a relatively large set of occluders. The algorithm is fast to calculate and therefore also useful for scenes of moderate complexity and walkthroughs with over 20 frames per second. Occlusion is calculated dynamically and does not rely on any visibility precalculation or occluder preselection. Speed-ups of one order of magnitude can be obtained.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-353, pages = "61--73", year = "1999", title = "Improved image-based impostors for accelerated rendering", author = "Xavier Decoret and Gernot Schaufler and Francois Sillion and Julie Dorsey", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-353", abstract = "This paper describes the successful combination of pre-generated and dynamically updated image-based representations to accelerate the visualization of complex virtual environments. We introduce a new type of impostor, which has the desirable property of limiting de-occlusion errors to a user-specified amount. This impostor, composed of multiple layers of textured meshes, replaces the distant geometry and is much faster to draw. It captures the relevant depth complexity in the model without resorting to a complete sampling of the scene. We show that layers can be dynamically updated during visualization. This guarantees bounded scene complexity in each frame and also exploits temporal coherence to improve image quality when possible. We demonstrate the strengths of this approach in the context of city walkthroughs.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-354, pages = "73--82", year = "1999", title = "Interactive Multiresolution Editing of Arbitrary Meshes", author = "Seungyong Lee", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-354", abstract = "This paper presents a novel approach to multiresolution editing of a triangular mesh. The basic idea is to embed an editing area of a mesh onto a 2D rectangle and interpolate the user-specified editing information over the 2D rectangle. The result of the interpolation is mapped back to the editing area and then used to update the mesh. We adopt harmonic maps for the embedding and multilevel B-splines for the interpolation. The proposed mesh editing technique can handle an arbitrary mesh without any preprocessing such as remeshing. It runs fast enough to support interactive editing and produces intuitive editing results.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-355, pages = "83--94", year = "1999", title = "Generalized View-Dependent Simplification", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-355", author = "Jihad El-Sana and Amitabh Varshney", abstract = "We propose a technique for performing view-dependent geometry and topology simplifications for level-of-detail-based renderings of large models. The algorithm proceeds by preprocessing the input dataset into a binary tree, the view-dependence tree of general vertex-pair collapses. A subset of the Delaunay edges is used to limit the number of vertex pairs considered for topology simplification. Dependencies to avoid mesh foldovers in manifold regions of the input object are stored in the view-dependence tree in an implicit fashion. We have observed that this not only reduces the space requirements by a factor of two, it also highly localizes the memory accesses at run time. The view-dependence tree is used at run time to generate the triangles for display. We also propose a cubic-spline-based distance metric that can be used to unify the geometry and topology simplifications by considering the vertex positions and normals in an integrated manner.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-356, pages = "95--106", year = "1999", title = "An information theory framework for the analysis of scene complexity", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-356", author = "Miquel Feixas and Esteve del Acebo and Philippe Bekaert and Mateu Sber", abstract = "In this paper we present a new framework for the analysis of scene visibility and radiosity complexity. We introduce a number of complexity measures from information theory quantifying how difficult it is to compute with accuracy the visibility and radiosity in a scene. We define the continuous mutual information as a complexity measure of a scene, independent of whatever discretisation, and discrete mutual information as the complexity of a discretised scene. Mutual information can be understood as the degree of correlation or dependence between all the points or patches of a scene. Thus, low complexity corresponds to low correlation and vice versa. Experiments illustrating that the best mesh of a given scene among a number of alternatives corresponds to the one with the highest discrete mutual information, indicate the feasibility of the approach. Unlike continuous mutual information, which is very cheap to compute, the computation of discrete mutual information can however be quite demanding. We will develop cheap complexity measure estimates and derive practical algorithms from this framework in future work.", editor = "P. Brunet and R. Scopigno", keywords = "Rendering, radiosity, Monte Carlo, information theory, entropy, mutual information", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-357, pages = "107--118", year = "1999", title = "A Free Form Feature Taxonomy", author = "M. Fontana and F. Giannini and M. Meirana", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-357", abstract = "In this paper the notion of free form feature for aesthetic design is presented. The design of industrial products constituted by free form surfaces is done by using CAD systems representing curves and surfaces by means of NURBS functions, which are usually defined by low level entities that are not intuitive and require some knowledge of the mathematical language. Similarly to the feature-based approach adopted by CAD systems for classical mechanical design, a set of high level modelling entities which provides commonly performed shape modifications has been identified. Particularly, the paper suggests a classification of the so-called detail features for an aesthetic and/or functional characterization of predefined free form surfaces. Feature types are formally described by means of an analytical definition of the surface modification through deformation and elimination laws. A topological classification is then given according to the application domain of such laws. A further sub-classification of morphological types is then suggested according to geometric properties of weak convexity and concavity for the resulting modified shape, leading to a taxonomy of simple free form features meaningful for aesthetic design.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-358, pages = "119--130", year = "1999", title = "A Shrink Wrapping Approach to Remeshing Polygonal Surface", author = "Leif P. Kobbelt and Jens Vorsatz and Ulf Labsik and Hans-Peter Seidel", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-358", abstract = "Due to their simplicity and flexibility, polygonal meshes are about to become the standard representation for surface geometry in computer graphics applications. Some algorithms in the context of multiresolution representation and modeling can be performed much more efficiently and robustly if the underlying surface tesselations have the special subdivision connectivity. In this paper, we propose a new algorithm for converting a given unstructured triangle mesh into one having subdivision connectivity. The basic idea is to simulate the shrink wrapping process by adapting the deformable surface technique known from image processing. The resulting algorithm generates subdivision connectivity meshes whose base meshes only have a very small number of triangles. The iterative optimization process that distributes the mesh vertices over the given surface geometry guarantees low local distortion of the triangular faces. We show several examples and applications including the progressive transmission of subdivision surfaces.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-359, pages = "131--138", year = "1999", title = "Improved Laplacian Smoothing of Noisy Surface Meshes", author = "J. Vollmer and R. Mencl and and H. M{\"o}ller", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-359", abstract = "This paper presents a technique for smoothing polygonal surface meshes that avoids the well-known problem of deformation and shrinkage caused by many smoothing methods, like e.g. the Laplacian algorithm. The basic idea is to push the vertices of the smoothed mesh back towards their previous locations. This technique can be also used in order to smooth unstructured point sets, by reconstructing a temporary surface mesh to which the smoothing technique is applied. The key observation is that a surface mesh which is not necessarily topologically correct, but which can efficiently be reconstructed, is sufficient for that purpose.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @Article{EVL-1999-36, pages = "241--267", year = "1999", title = "Minimizing support structures and trapped area in two-dimensional layered manufacturing", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-36", author = "Jayanth Majhi and Ravi Janardan and J{\"o}rg Schwerdt and Michiel Smid and Prosenjit Gupta", abstract = "Algorithms are given for the two-dimensional versions of optimization problems arising in layered manufacturing, where a polygonal object is built by slicing its CAD model and manufacturing the slices successively. The problems considered are minimizing (i) the contact-length between the supports and the manufactured object, (ii) the area of the support structures used, and (iii) the area of the so-called trapped regions---factors that affect the cost and quality of the process.", month = apr, volume = "12", keywords = "Layered manufacturing; Computational geometry; Optimization", number = "3-4", journal = "Computational Geometry", } @InProceedings{EVL-1999-360, pages = "139--150", year = "1999", title = "An Adaptive Method for Area Light Sources and Daylight in Ray Tracing", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-360", author = "Jacques Zaninetti and Pierre Boy and Bernard Peroche", abstract = "This paper proposes an adaptive method for taking both (diffuse or not) planar area light sources and daylight into account in a ray tracing environment which separates the calculation of direct and indirect illumination. In a given point, direct illumination due to a light source or to natural light is represented by a vector, the direction and magnitude of which being computed through an adaptive area approach, which is driven by the solid angle according to which a part of the source is seen from the current point. In the case of unoccluded diffuse polygonal sources, an analytical formula is used which gives an exact value for this vector.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-361, pages = "151--160", year = "1999", title = "Adaptive Acquisition of Lumigraphs from Synthetic Scenes", author = "Hartmut Schirmacher and Wolfgang Heidrich and Hans-Peter Seidel", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-361", abstract = "Light fields and Lumigraphs are capable of rendering scenes of arbitrary geometrical or illumination complexity in real time. They are thus interesting ways of interacting with both recorded real-world and high-quality synthetic scenes. Unfortunately, both light fields and Lumigraph rely on a dense sampling of the illumination to provide a good rendering quality. This induces high costs both in terms of storage requirements and computational resources for the image acquisition. Techniques for acquiring adaptive light field and Lumigraph representations are thus mandatory for practical applications. In this paper we present a method for the adaptive acquisition of images for Lumigraphs from synthetic scenes. Using image warping to predict the potential improvement in image quality when adding a certain view, we decide which new views of the scene should be rendered and added to the light field. This a-priori error estimator accounts for both visibility problems and illumination effects such as specular highlights.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-362, pages = "161--172", year = "1999", title = "Compact Metallic Reflectance Models", author = "Laszlo Neumann and Attila Neumann and Laszlo Szirmay-Kalos", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-362", abstract = "The paper presents simple, physically plausible, but not physically based reflectance models for metals and other specular materials. So far there has been no metallic BRDF model that is easy to compute, suitable for fast importance sampling and is physically plausible. This gap is filled by appropriate modifications of the Phong, Blinn and the Ward models. The Phong and the Blinn models are known not to have metallic characteristics. On the other hand, this paper also shows that the Cook-Torrance and the Ward models are not physically plausible, because of their behavior at grazing angles. We also compare the previous and the newly proposed models. Finally, the generated images demonstrate how the metallic impression can be provided by the new models.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", keywords = "Reflectance function, BRDF representation, albedo function, importance sampling.", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-363, pages = "173--182", year = "1999", title = "Capturing and Re-Using Rendition Styles for Non-Photorealistic Rendering", author = "J. Hamel and T. Strothotte", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-363", abstract = "Rendering high-quality non-photorealistic images of a given geometric model is often associated with a considerable amount of effort on the part of a user to fine-tune the rendition. In this paper we introduce a method and tools for re-using the user's effort invested in one model for the rendering of other models. Our method uses templates to describe rendition styles. The paper gives a number of examples of the successful transfer of styles from one model to another.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-364, pages = "183--194", year = "1999", title = "An Interactive Designing System with Virtual Sculpting and Virtual Woodcut Printing", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-364", author = "S. Mizuno and M. Okada and J. Toriwak", abstract = "In this paper, we propose an interactive designing method and a system based on it to create 3D objects and 2D images. This system consists of two subsystems for virtual sculpting to create a 3D shape and virtual printing to produce a picture with a printing block. In the virtual sculpting subsystem, a user can form solid objects with curved surfaces as if sculpting them. The user operates virtual chisels, and can remove or attach arbitrary shapes of ellipsoids or cubes from or to the workpiece. A 3D object generated by virtual sculpting looks like a real wooden sculpture. If using a board as a workpiece, a user can generate a virtual printing block. In the virtual printing subsystem, a user can synthesize a woodcut printing image from the virtual printing block mentioned above, a virtual paper sheet, and a printing brush. The user can synthesize a realistic woodcut print with a procedure similar to the actual woodcut printing.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-365, pages = "195--208", year = "1999", title = "Computer-Generated Graphite Pencil Rendering of 3{D} Polygonal Models", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-365", author = "Mario C. Sousa and John W. Buchanan", abstract = "Researchers in non-photorealistic rendering have investigated the display of three-dimensional worlds using various display models. In particular, recent work has focused on the modeling of traditional artistic media and styles such as pen-and-ink illustration and watercolor painting. By providing 3D rendering systems that use these alternative display models users can generate traditional illustration renderings of their three-dimensional worlds. In this paper we present our graphite pencil 3D renderer. We have broken the problem of simulating pencil drawing down into four fundamental parts: (1) simulating the drawing materials (graphite pencil and drawing paper, blenders and kneaded eraser), (2) modeling the drawing primitives (individual pencil strokes and mark-making to create tones and textures), (3) simulating the basic rendering techniques used by artists and illustrators familiar with pencil rendering, and (4) modeling the control of the drawing composition. Each part builds upon the others and is essential to developing the framework for higher-level rendering methods and tools. In this paper we present parts 2, 3, and 4 of our research. We present non-photorealistic graphite pencil rendering methods for outlining and shading. We also present the control of drawing steps from preparatory sketches to finished rendering results. We demonstrate the capabilities of our approach with a variety of images generated from 3D models.", editor = "P. Brunet and R. Scopigno", keywords = "Nonrealistic rendering, rendering systems, natural media simulation, paint systems.", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-366, pages = "209--220", year = "1999", title = "Weighted Multipass Methods for Global Illumination", author = "Frank Suykens and Yves D. Willems", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-366", abstract = "In multipass rendering, care has to be taken to include all light transport only once in the final solution. Therefore the different methods in current multipass configurations handle a perfectly disjunct part of the light transport. In this paper a Monte Carlo variance reduction technique is presented that probabilistically weights overlapping transport between different methods. A good heuristic for the weights is derived so that strengths of the respective methods are retained. The technique is applied to a combination of radiosity and bidirectional path tracing and significant improvement is obtained over the non-weighted combination. This method promises to be a very useful extension to other multipass algorithms as well.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-367, pages = "221--232", year = "1999", title = "A Practical Analysis of Clustering Strategies for Hierarchical Radiosity", author = "Jean-Marc Hasenfratz and Cyrille Damez and Francois Sillion and George Drettakis", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-367", abstract = "The calculation of radiant energy balance in complex scenes has been made possible by hierarchical radiosity methods based on clustering mechanisms. Although clustering offers an elegant theoretical solution by reducing the asymptotic complexity of the algorithm, its practical use raises many difficulties, and may result in image artifacts or unexpected behavior. This paper proposes a detailed analysis of the expectations placed on clustering and compares the relative merits of existing, as well as newly introduced, clustering algorithms. This comparison starts from the precise definition of various clustering strategies based on a taxonomy of data structures and construction algorithms, and proceeds to an experimental study of the clustering behavior for real-world scenes. Interestingly, we observe that for some scenes light is difficult to simulate even with clustering. Our results lead to a series of observations characterizing the adequacy of clustering methods for meeting such diverse goals as progressive solution improvement, efficient ray casting acceleration, and faithful representation of object density for approximate visibility calculations.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-368, pages = "233--244", year = "1999", title = "Stochastic Iteration for Non-diffuse Global Illumination", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-368", author = "Laszlo Szirmay-Kalos", abstract = "This paper presents a single-pass, view-dependent method to solve the rendering equation, using a stochastic iterational scheme where the transport operator is selected randomly in each iteration. The requirements of convergence are given for the general case. To demonstrate the basic idea, a very simple,continuous random transport operator is examined, which gives back the light tracing algorithm incorporating Russian roulette. Then, a new mixed continuous and finite-element based iteration method is proposed, which uses ray-bundles to transfer the radiance in a single random direction. The resulting algorithm is fast, it provides initial results in seconds and accurate solutions in minutes and does not suffer from the error accumulation problem and the high memory demand of other finite-element and hierarchical approaches.", editor = "P. Brunet and R. Scopigno", keywords = "Rendering equation, global radiance, Monte-Carlo integration, light-tracing, global ray-bundle tracing.", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-369, pages = "245--256", year = "1999", title = "Texturing 3d Models of Real World Objects from Multiple Unregistered Photographic Views", author = "Peter J. Neugebauer and Konrad Klein", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-369", abstract = "As the efficiency of computer graphic rendering methods is increasing, generating realistic models is now becoming a limiting factor. In this paper we present a new technique to enhance already existing geometry models of real world objects with textures reconstructed from a sparse set of unregistered still photographs. The aim of the proposed technique is the generation of nearly photo-realistic models of arbitrarily shaped objects with minimal effort. In our approach, we require neither a prior calibration of the camera nor a high precision of the user's interaction. Two main problems have to be addressed of which the first is the recovery of the unknown positions and parameters of the camera. An initial estimate of the orientation is calculated from interactively selected point correspondences. Subsequently, the unknown parameters are accurately calculated by minimising a blend of objective functions in a 3D-2D projective registration approach. The key point of the proposed method of registration is a novel filtering approach which utilises the spatial information provided by the geometry model. Second, the individual images have to be combined yielding a set of consistent texture maps. We present a robust method to recover the texture from the photographs thereby preserving high spatial frequencies and eliminating artifacts, particularly specular highlights. Parts of the object not seen in any of the photographs are interpolated in the textured model. Results are shown for three complex example objects with different materials and numerous self-occlusions.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @Article{EVL-1999-37, pages = "3--19", year = "1999", title = "Rotational polygon containment and minimum enclosure using only robust 2{D} constructions", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-37", author = "Victor J. Milenkovic", abstract = "An algorithm and a robust floating point implementation is given for rotational polygon containment: given polygons P1,P2,P3,...,Pk and a container polygon C , find rotations and translations for the k polygons that place them into the container without overlapping. A version of the algorithm and implementation also solves rotational minimum enclosure: given a class C of container polygons, find a container C∈C of minimum area for which containment has a solution. The minimum enclosure is approximate: it bounds the minimum area between $(1-\epsilon) A$ and A. Experiments indicate that finding the minimum enclosure is practical for k=2,3 but not larger unless optimality is sacrificed or angles ranges are limited (although these solutions can still be useful). Important applications for these algorithm to industrial problems are discussed. The paper also gives practical algorithms and numerical techniques for robustly calculating polygon set intersection, Minkowski sum, and range intersection: the intersection of a polygon with itself as it rotates through a range of angles. In particular, it introduces nearest pair rounding, which allows all these calculations to be carried out in rounded floating point arithmetic.", month = may, volume = "13", keywords = "Layout; Packing or nesting of irregular polygons; Containment; Minimum enclosure; Robust geometry; Geometric rounding", number = "1", journal = "Computational Geometry", } @InProceedings{EVL-1999-370, pages = "257--264", year = "1999", title = "Virtual Dunhuang Art Cave: {A} Cave within a {CAVE}", author = "B. Lutz and M. Weintke", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-370", abstract = "Virtual Reality can present historical places in a three-dimensional and interactive way, giving visitors a photorealistic impression of objects. Not only existing scenarios can be shown, but VR can also be used to rebuild scenarios that were damaged or destroyed a long time ago, giving new life to the cultural heritage. We used Virtual Reality to present the Mogao Grottos in Dunhuang. This cave site is one of the most important cultural and religious places by the ancient Silk Road. The presentation is to give visitors the impression of visiting the cave site and provide information about the caves, paintings and statues in an interesting way. To achieve this, we developed a new, intuitive interaction paradigm, which enables the user to explore the caves. To give observers a photorealistic impression of the caves and to create a feeling of immersion, innovative rendering techniques were integrated. The resulting presentation combines Virtual Reality and archaeology to give tourists a realistic experience of this cave site and to support scientists in their research work.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-371, pages = "265--276", year = "1999", title = "A New Method of Image Mosaicking and Its Application to Cultural Heritage Representation", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-371", author = "G. M. Cortelazzo and L. Lucchese", abstract = "This paper presents an original two-step procedure for estimating projective transformations between pairs of images: first, the transformation between the images is approximated as an affine transformation; second, this estimate is refined into that of a projective transformation. This strategy for matching projective views is computationally very efficient. The proposed method can be applied both to mosaicking of high resolution images of planar textured objects (e.g., frescoes and paintings), with subpixel accuracy, and to construction of panoramic images. Practical examples of mosaicking of cultural heritage imagery obtained by using the presented procedure are discussed in the paper.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-372, pages = "277--286", year = "1999", title = "A Translucent Sketchpad for the Virtual Table Exploring Motion-based Gesture Recognition", author = "L. M. Encarnacao and O. Bimber and D. Schmalstieg and S. D. Chandler", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-372", abstract = "The Virtual Table presents stereoscopic graphics to a user in a workbench-like setting. For this device, a user interface and new interaction techniques have been developed based on transparent props -a tracked hand-held pen and a pad. These props, particularly the pad, are augmented with 3D graphics from the Virtual Table’s display that can serve as a palette for tools and controls as well as a window-like see-through interface, a plane-shaped and through-the-plane tool, supporting a variety of new interaction techniques. This paper reports on an extension of this user-interface design space which uses gestural input to create and control solid geometries for CAD and conceptual design. The application of gestural interfaces is a common method for interacting with virtual environments on a habitual and natural basis. The motion-based gesture recognition presented here uses Fuzzy Logic to support a predictable, flexible, and efficient learning process. This new interaction paradigm greatly increases the Virtual Table’s suitability for design tasks. Traditional CAD dialogue can be combined with intuitive rapid sketching of geometry on the pad. Additionally, the resulting events and objects can be associated with scene details below the translucent tablet.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-373, pages = "287--296", year = "1999", title = "Interactive Mechanical Design Variation for Haptics and {CAD}", author = "Donald D. Nelson and Elaine Cohen", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-373", abstract = "A fast design variation technique for mechanical systems is presented. It is used to interactively optimize mechanical characteristics while 'self-assembling' or satisfying large systems of mechanical constraints. The high speed method is central to providing inverse dynamics force feedback in haptics and control applications. Performance advantages with the use of augmented coordinates for inverse dynamics of closed loop topologies are also noted. The interaction framework allows manipulation of complex assemblies while maintaining kinematically admissible configurations though linkage and joint limit constraints. Furthermore, design variables such as link length can be treated as free variables and optimized to meet design criteria such as assembly dexterity. Assemblies with flexible bodies fit naturally within this framework. Thus, the contribution of this paper is the advancement of techniques in augmented coordinates for the kinematic and force feedback interaction with virtual mechanical assembly design optimization at force control rates.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-374, pages = "297--308", year = "1999", title = "The Hybrid World of Virtual Environments", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-374", author = "Shamus Smith and David Duke", abstract = "Much of the work concerned with virtual environments has addressed the development of new rendering technologies or interaction techniques. As the technology matures and becomes adopted in a wider range of applications, there is, however, a need to better understand how this technology can be accommodated in software engineering practice. A particular challenge presented by virtual environments is the complexity of the interaction that is supported, and sometimes necessary, for a particular task. Methods such as finite-state automata which are used to represent and design dialogue components for more conventional interfaces, e.g. using direct manipulation within a desktop model, do not seem to capture adequately the style of interaction that is afforded by richer input devices and graphical models. In this paper, we suggest that virtual environments are, fundamentally, what are known as hybrid systems. Building on this insight, we demonstrate how techniques developed for modelling hybrid systems can be used to represent and understand virtual interaction in a way that can be used in the specification and design phases of software development, and which have the potential to support prototyping and analysis of virtual interfaces.", editor = "P. Brunet and R. Scopigno", keywords = "Virtual Environments, hybrid systems, interaction techniques, VE design, HyNet.", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-375, pages = "309--318", year = "1999", title = "An Informed Environment dedicated to the simulation of virtual humans in urban context", author = "Nathalie Farenc and Ronan Boulic and Daniel Thalmann", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-375", abstract = "In this paper, we outline the creation of an Informed Environment, dedicated to urban life simulation.We propose methods and tools for creating and providing the information necessary for animating virtual humans in a city using an Informed Environment. The Informed Environment is based on a hierarchical decomposition of a urban scene into Environment Entities providing geometrical information as well as semantic notions, thus allowing a more realistic simulation of human behaviour. In this manner, virtual humans can integrate with a certain kind of urban knowledge.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-376, pages = "319--330", year = "1999", title = "Partitioning and Handling Massive Models for Interactive Collision Detection", author = "A. Wilson and E. Larsen and D. Manocha and M. C. Lin", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-376", abstract = "We describe an approach for interactive collision detection and proximity computations on massive models composed of millions of geometric primitives. We address issues related to interactive data access and processing in a large geometric database, which may not fit into main memory of typical desktop workstations or computers. We present a new algorithm using overlap graphs for localizing the 'regions of interest' within a massive model, thereby reducing runtime memory requirements. The overlap graph is computed off-line, pre-processed using graph partitioning algorithms, and modified on the fly as needed. At run time, we traverse localized sub-graphs to check the corresponding geometry for proximity and pre-fetch geometry and auxiliary data structures. To perform interactive proximity queries, we use bounding-volume hierarchies and take advantage of spatial and temporal coherence. Based on the proposed algorithms, we have developed a system called IMMPACT and used it for interaction with a CAD model of a power plant consisting of over 15 million triangles. We are able to perform a number of proximity queries in real-time on such a model. In terms of model complexity and application to large models, we have improved the performance of interactive collision detection and proximity computation algorithms by an order of magnitude.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-377, pages = "331--338", year = "1999", title = "Seamless Integration of Databases in {VR} for Constructing Virtual Environments", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-377", author = "Ingo Soetebier and Ralf Durner and Norbert Braun", abstract = "An approach for authoring virtual environments within the virtual environments themselves is presented, integrating a database containing arbitrary components that are used to construct the 3D scene. The issues important to a seamless integration of the database, such as multimedia data storage and database linkage are discussed, with the focus on the human-computer interaction component. A concept for a 3D database interface is described for query, presentation and usage of query results in the virtual environment. Finally, an implementation of the concept using VRML and Java is presented.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-378, pages = "339--348", year = "1999", title = "Image Morphing with Feature Preserving Texture", author = "Ayellet Tal and Gershon Elber", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-378", abstract = "Image metamorphosis as an animation tool has mostly been employed in the context of the entire image. This work explores the use of isolated and focused image based metamorphosis between two-dimensional objects, while capturing the features, colors, and textures of the objects. This pinpointed approach allows one to independently overlay several such dynamic shapes, without any bleeding of one shape into another. Hence, shape blending and metamorphosis of two-dimensional objects can be exploited as animated sequences of clip arts.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-379, pages = "349--358", year = "1999", title = "Efficient and Handy Texture Mapping on 3{D} Surfaces", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-379", author = "Kenji Matsushita and Toyohisa Kaneko", abstract = "There has been a rapid technical progress in three-dimensional (3D) computer graphics. But gathering surface and texture data is yet a laborious task. This paper addresses the problem of mapping photographic images on the surface of a 3D object whose geometric data are already known. We propose an efficient and handy method for acquiring textures and mapping them precisely on the surface, employing a digital camera alone. We describe an algorithm for selecting a minimal number of camera positions that can cover the entire surface of a given object and also an algorithm to determine camera's position and direction for each photograph taken so as to paste it to the corresponding surfaces precisely. We obtained a matching accuracy within a pixel on a surface through three experimental examples, by which the practicability of our method is demonstrated.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @Article{EVL-1999-38, pages = "21--47", year = "1999", title = "Point labeling with sliding labels", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-38", author = "Marc van Kreveld and Tycho Strijk and Alexander Wolff", abstract = "This paper discusses algorithms for labeling sets of points in the plane, where labels are not restricted to some finite number of positions. We show that continuously sliding labels allow more points to be labeled both in theory and in practice. We define six different models of labeling. We compare models by analyzing how many more points can receive labels under one model than another. We show that maximizing the number of labeled points is NP-hard in the most general of the new models. Nevertheless, we give a polynomial-time approximation scheme and a simple and efficient factor- (1)/(2) approximation algorithm for each of the new models. Finally, we give experimental results based on the factor- (1)/(2) approximation algorithm to compare the models in practice. We also compare this algorithm experimentally to other algorithms suggested in the literature.", month = may, volume = "13", keywords = "Map labeling; Point annotation; Greedy approximation algorithm; Approximation scheme", number = "1", journal = "Computational Geometry", } @InProceedings{EVL-1999-380, pages = "359--368", year = "1999", title = "Data Intermixing and Multi-Volume Rendering", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-380", author = "Wenli Cai and Georgios Sakas", abstract = "The main difference between multi-volume rendering and mono-volume rendering is data intermixing. In this paper, we present three levels of data intermixing and their rendering pipelines in direct multi-volume rendering, which discriminate image level intensity intermixing, accumulation level opacity intermixing, and illumination model level parameter intermixing. In the context of radiotherapy treatment planning, different data intermixing methods are applied to three volumes, including CT volume, Dose volume, and Segmentation volume, to compare the features of different data intermixing methods.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-381, pages = "369--376", year = "1999", title = "Fast Polyhedral Cell Sorting for Interactive Rendering of UnstructuredGrids", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-381", author = "Jo{\~{a}}o Comba and James T. Klosowski and Nelson Max and Joseph S. B. Mitchell Claudio T. Silva and Peter L. Williams", abstract = "Direct volume rendering based on projective methods works by projecting, in visibility order, the polyhedral cells of a mesh onto the image plane, and incrementally compositing the cell's color and opacity into the final image. Crucial to this method is the computation of a visibility ordering of the cells. If the mesh is 'well-behaved' (acyclic and convex), then the MPVO method of Williams provides a very fast sorting algorithm; however, this method only computes an approximate ordering in general datasets, resulting in visual artifacts when rendered. A recent method of Silva et al. removed the assumption that the mesh is convex, by means of a sweep algorithm used in conjunction with the MPVO method; their algorithm is substantially faster than previous exact methods for general meshes. In this paper we propose a new technique, which we call BSP-XMPVO, which is based on a fast and simple way of using binary space partitions on the boundary elements of the mesh to augment the ordering produced by MPVO. Our results are shown to be orders of magnitude better than previous exact methods of sorting cells.", editor = "P. Brunet and R. Scopigno", keywords = "Volume rendering, scientific visualization, finite element methods, depth ordering, volume visualization, visibility ordering.", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-382, pages = "377--384", year = "1999", title = "Fast Lines: a Span by Span Method", author = "V. Boyer and J. J. Bourdin", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-382", abstract = "Straight line's scan conversion and drawing is a major field in computer graphics. Algorithm's time computation is very important. Nowadays, most of research papers suggest improvements of the DDA method that was first presented by J. Bresenham. But other approaches exist as well like combinatory analysis and linguistic methods. Both of them use multiple string copies that slow down the efficiency of the algorithms. This paper proposes a new algorithm based on a careful analysis of the line segments' properties some of them previously unused. Our algorithm is proved significantly faster than previously published ones.", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InProceedings{EVL-1999-383, pages = "385--395", year = "1999", title = "An Efficient 2 1/2 {D} Rendering and Compositing System", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-383", author = "Max Froumentin and Philip Willis", abstract = "We describe a method for doing image compositing using either 2D geometric shapes or raster images as input primitives. The resolution of the final image is virtually unlimited but, as no frame buffer is used, performance is much less dependant on resolution than with standard painting programs, allowing rendering very large images in reasonable time. Many standard features found in compositing programs have been implemented, like hierarchical data structures for input primitives, lighting control for each layer and filter operations (for antialiasing or defocus).", editor = "P. Brunet and R. Scopigno", volume = "18(3)", booktitle = "Computer Graphics Forum (Eurographics '99)", publisher = "The Eurographics Association and Blackwell Publishers", } @InCollection{EVL-1999-384, pages = "1--12", year = "1999", title = "Acquiring a Radiance Distribution to Superimpose Virtual Objects onto a Real Scene", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-384", author = "Imari Sato and Yoichi Sato and Katsushi Ikeuchi", abstract = "This paper describes a new method for superimposing virtual objects with correct shadings onto an image of a real scene. Unlike the previously proposed methods, our method can measure a radiance distribution of a real scene automatically and use it for superimposing virtual objects appropriately onto a real scene. First, a geometric model of the scene is constructed from a pair of omnidirectional images by using an omnidirectional stereo algorithm. Then, radiance of the scene is computed from a sequence of omnidirectional images taken with different shutter speeds and mapped onto the constructed geometric model. The radiance distribution mapped onto the geometric model is used for rendering virtual objects superimposed onto the scene image. As a result, even for a complex radiance distribution, our method can superimpose virtual objects with convincing shadings and shadows cast onto the real scene. We successfully tested the proposed method by using real images to show its effectiveness.", editor = "Hans Hagen", keywords = "Computer graphics, computer vision, augmented reality, illumination distribution measurement, omnidirectional stereo algorithm.", volume = "5 (1)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-385, pages = "13--29", year = "1999", title = "Dynamic Scene Occlusion Culling", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-385", author = "Oded Sudarsky and Craig Gotsman", abstract = "Large, complex 3D scenes are best rendered in an output-sensitive way, i.e., in time largely independent of the entire scene model's complexity. Occlusion culling is one of the key techniques for output-sensitive rendering. We generalize existing occlusion culling algorithms, intended for static scenes, to handle dynamic scenes having numerous moving objects. The data structure used by an occlusion culling method is updated to reflect the objects' possible positions. To avoid updating the structure for every dynamic object at each frame, a temporal bounding volume (TBV) is created for each occluded dynamic object, using some known constraints on the object's motion. The TBV is inserted into the structure instead of the object. Subsequently, the object is ignored as long as the TBV is occluded and guaranteed to contain the object. The generalized algorithms' rendering time is linearly affected only by the scene's visible parts, not by hidden parts or by occluded dynamic objects. Our techniques also save communications in distributed graphic systems, e.g., multiuser virtual environments, by eliminating update messages for hidden dynamic objects. We demonstrate the adaptation of two occlusion culling algorithms to dynamic scenes: hierarchical Z-buffering and BSP tree projection.", editor = "Hans Hagen", keywords = "Occlusion culling, dynamic scenes, distributed multiuser virtual environments, hierarchical Z-buffer, octrees, BSP tree.", volume = "5 (1)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-386, pages = "30--46", year = "1999", title = "On a Construction of a Hierarchy of Best Linear Spline Approximations Using Repeated Bisection", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-386", author = "Bernd Hamann and Benjamin W. Jordan and David F. Wiley", abstract = "We present a method for the construction of hierarchies of single-valued functions in one, two, and three variables. The input to our method is a coarse decomposition of the compact domain of a function in the form of an interval (univariate case), triangles (bivariate case), or tetrahedra (trivariate case). We compute best linear spline approximations, understood in an integral least squares sense, for functions defined over such triangulations and refine triangulations using repeated bisection. This requires the identification of the interval (triangle, tetrahedron) with largest error and splitting it into two intervals (triangles, tetrahedra). Each bisection step requires the recomputation of all spline coefficients due to the global nature of the best approximation problem. Nevertheless, this can be done efficiently by bisecting multiple intervals (triangles, tetrahedra) in one step and by reducing the bandwidths of the matrices resulting from the normal equations.", editor = "Hans Hagen", keywords = "Approximation, bisection, best approximation, grid generation, hierarchical representation, linear spline, multiresolution method, scattered data, spline, triangulation, unstructured grid, visualization.", volume = "5 (1)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-387, pages = "47--61", year = "1999", title = "Edgebreaker: Connectivity Compression for Triangle Meshes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-387", author = "Jarek Rossignac", abstract = "Edgebreaker is a simple scheme for compressing the triangle/vertex incidence graphs (sometimes called connectivity or topology) of three-dimensional triangle meshes. Edgebreaker improves upon the storage required by previously reported schemes, most of which can guarantee only an O(t log(t)) storage cost for the incidence graph of a mesh of t triangles. Edgebreaker requires at most 2t bits for any mesh homeomorphic to a sphere and supports fully general meshes by using additional storage per handle and hole. For large meshes, entropy coding yields less than 1.5 bits per triangle. Edgebreaker's compression and decompression processes perform identical traversals of the mesh from one triangle to an adjacent one. At each stage, compression produces an op-code describing the topological relation between the current triangle and the boundary of the remaining part of the mesh. Decompression uses these op-codes to reconstruct the entire incidence graph. Because Edgebreaker's compression and decompression are independent of the vertex locations, they may be combined with a variety of vertex-compressing techniques that exploit topological information about the mesh to better estimate vertex locations. Edgebreaker may be used to compress the connectivity of an entire mesh bounding a 3D polyhedron or the connectivity of a triangulated surface patch whose boundary need not be encoded. The paper also offers a comparative survey of the rapidly growing field of geometric compression.", editor = "Hans Hagen", keywords = "Compression, 3D models, geometric representation, computer graphics, solid modeling", volume = "5 (1)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-388, year = "1999", title = "Adaptive Projection Operators in Multiresolution Scientific Visualization", author = "Mario Ohlberger and Martin Rumpf", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-388", abstract = "Recently, multiresolution visualization methods have become an indispensable ingredient of real-time interactive postprocessing. The enormous databases, typically coming along with some hierarchical structure, are locally resolved on different levels of detail to achieve a significant savings of CPU and rendering time. Here, the method of adaptive projection and the corresponding operators on data functions, respectively, are introduced. They are defined and discussed as mathematically rigorous foundations for multiresolution data analysis. Keeping in mind data from efficient numerical multigrid methods, this approach applies to hierarchical nested grids consisting of elements which are any tensor product of simplices, generated recursively by an arbitrary, finite set of refinement rules from some coarse grid. The corresponding visualization algorithms, e.g., color shading on slices or isosurface rendering, are confined to an appropriate depth-first traversal of the grid hierarchy. A continuous projection of the data onto an adaptive, extracted subgrid is thereby calculated recursively. The presented concept covers different methods of local error measurement, time-dependent data which have to be interpolated from a sequence of key frames, and a tool for local data focusing. Furthermore, it allows for a continuous level of detail", editor = "Hans Hagen", volume = "5 (1)", keywords = "Adaptive projection operators, multiresolution, efficient data analysis, error indicators, hierarchical grids, visualization of large data sets.", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-389, pages = "62--73", year = "1999", title = "Real-Time Elastic Deformations of Soft Tissues for Surgery Simulation St{\'{e}}phane Cotin, Herv{\'{e}} Delingette, and Nicholas Ayache", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-389", author = "St{\'{e}}phane Cotin and Herv{\'{e}} Delingette and Nicholas Ayache", abstract = "In this paper, we describe a new method for surgery simulation including a volumetric model built from medical images and an elastic modeling of the deformations. The physical model is based on elasticity theory which suitably links the shape of deformable bodies and the forces associated with the deformation. A real-time computation of the deformation is possible thanks to a preprocessing of elementary deformations derived from a finite element method. This method has been implemented in a system including a force feedback device and a collision detection algorithm. The simulator works in real-time with a high resolution liver model.", editor = "Hans Hagen", keywords = "Surgery simulation, deformable models, real-time, force feedback, soft tissue modeling, finite element.", volume = "5 (1)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @Article{EVL-1999-39, pages = "49--64", year = "1999", title = "Multiresolution banded refinement to accelerate surface reconstruction from polygons", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-39", author = "James D. Fix and Richard E. Ladner", abstract = "We propose a method for constructing a tiling between a pair of planar polygons. Our technique uses multiresolution: tilings of lower resolution polygons are used to construct a tiling for the full resolution polygons. The tilings are constructed using banded refinement, by restricted dynamic programming, in roughly linear time and space. By contrast, the optimal dynamic programming method requires quadratic time and space. In our empirical study of surface reconstruction of brain contours our algorithm exhibited significant speedup over the optimal dynamic program, yet nearly always found an optimal reconstruction. Our approach appears to be generalizable to other geometric problems solvable by dynamic programming, and flexible enough to be tuned for varying data set characteristics.", month = may, volume = "12", keywords = "Polygon tiling; Multiresolution; Surface reconstruction; Dynamic programming; Shape correspondence", number = "1", journal = "Computational Geometry", } @InCollection{EVL-1999-390, pages = "196--209", year = "1999", title = "Efficient Skeletonization of Volumetric Objects", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-390", author = "Yong Zho and Arthur W. Toga", abstract = "Skeletonization promises to become a powerful tool for compact shape description, path planning, and other applications. However, current techniques can seldom efficiently process real, complicated 3D data sets, such as MRI and CT data of human organs. In this paper, we present an efficient voxel-coding based algorithm for skeletonization of 3D voxelized objects. The skeletons are interpreted as connected centerlines, consisting of sequences of medial points of consecutive clusters. These centerlines are initially extracted as paths of voxels, followed by medial point replacement, refinement, smoothness, and connection operations. The voxel-coding techniques have been proposed for each of these operations in a uniform and systematic fashion. In addition to preserving basic connectivity and centeredness, the algorithm is characterized by straightforward computation, no sensitivity to object boundary complexity, explicit extraction of ready-to-parameterize and branch-controlled skeletons, and efficient object hole detection. These issues are rarely discussed in traditional methods. A range of 3D medical MRI and CT data sets were used for testing the algorithm, demonstrating its utility.", editor = "Hans Hagen", keywords = "3D skeleton and centerline, medial axis, volume subdivision, region growing, hole detection, distance transformation, voxel-coding.", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-391, pages = "210--223", year = "1999", title = "Ray Casting Architectures for Volume Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-391", author = "Harvey Ray and Hanspeter Pfister and Deborah Silver and Todd A. Cook", abstract = "Real-time visualization of large volume datasets demands high performance computation, pushing the storage, processing, and data communication requirements to the limits of current technology. General purpose parallel processors have been used to visualize moderate size datasets at interactive frame ratReal-time visualization of large volume datasets demands high performance computation, pushing the storage, processing, and data communication requirements to the limits of current technology. General purpose parallel processors have been used to visualize moderate size datasets at interactive frame rates; however, the cost and size of these supercomputers inhibits the widespread use for real-time visualization. This paper surveys several special purpose architectures that seek to render volumes at interactive rates. These specialized visualization accelerators have cost, performance, and size advantages over parallel processors. All architectures implement ray casting using parallel and pipelined hardware. We introduce a new metric that normalizes performance to compare these architectures. The architectures included in this survey are VOGUE, VIRIM, Array Based Ray Casting, EM-Cube, and VIZARD II. We also discuss future applications of special purpose acceleratorses; however, the cost and size of these supercomputers inhibits the widespread use for real-time visualization. This paper surveys several special purpose architectures that seek to render volumes at interactive rates. These specialized visualization accelerators have cost, performance, and size advantages over parallel processors. All architectures implement ray casting using parallel and pipelined hardware. We introduce a new metric that normalizes performance to compare these architectures. The architectures included in this survey are VOGUE, VIRIM, Array Based Ray Casting, EM-Cube, and VIZARD II. We also discuss future applications of special purpose accelerators", editor = "Hans Hagen", keywords = "Volume rendering, interactive, ray casting, parallel architecture, VOGUE, VIRIM, array based ray casting, EM-Cube, VIZARD II.", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-392, pages = "224--237", year = "1999", title = "Simplification of Tetrahedral Meshes with Error Bounds", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-392", author = "Issac J. Trotts and Bernd Hamann and Kenneth I. Joy", abstract = "We present a method for the construction of multiple levels of tetrahedral meshes approximating a trivariate scalar-valued function at different levels of detail. Starting with an initial, high-resolution triangulation of a three-dimensional region, we construct coarser representation levels by collapsing edges of the mesh. Each triangulation defines a linear spline function, where the function values associated with the vertices are the spline coefficients. Error bounds are stored for individual tetrahedra and are updated as the mesh is simplified. Two algorithms are presented that simplify the mesh within prescribed error bounds. Each algorithm treats simplification on the mesh boundary. The result is a hierarchical data description suited for efficient visualization of large data sets at varying levels of detail.", editor = "Hans Hagen", keywords = "Mesh simplification, hierarchical representation, multiresolution method, scattered data, spline, tetrahedral mesh", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-393, pages = "238--250", year = "1999", title = "Interactive Ray Tracing for Volume Visualization", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-393", author = "Steven Parker and Michael Parker and Yarden Livnat and Peter-Pike Sloan and Charles Hansen and Peter Shirley", abstract = "We present a brute-force ray tracing system for interactive volume visualization. The system runs on a conventional (distributed) shared-memory multiprocessor machine. For each pixel we trace a ray through a volume to compute the color for that pixel. Although this method has high intrinsic computational cost, its simplicity and scalability make it ideal for large datasets on current high-end parallel systems. To gain efficiency several optimizations are used including a volume bricking scheme and a shallow data hierarchy. These optimizations are used in three separate visualization algorithms: isosurfacing of rectilinear data, isosurfacing of unstructured data, and maximum-intensity projection on rectilinear data. The system runs interactively (i.e., several frames per second) on an SGI Reality Monster. The graphics capabilities of the Reality Monster are used only for display of the final color image.", editor = "Hans Hagen", keywords = "Ray tracing, visualization, isosurface, maximum-intensity projection.", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-394, pages = "251--267", year = "1999", title = "Alias-Free Voxelization of Geometric Objects", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-394", author = "Milos Sramek and Arie E. Kaufman", abstract = "We introduce a new concept for alias-free voxelization of geometric objects based on a Voxelization model (V-model). The V-model of an object is its representation in three-dimensional continuous space by a trivariate density function. This function is sampled during the voxelization and the resulting values are stored in a volume buffer. This concept enables us to study general issues of sampling and rendering separately from object specific design issues. It provides us with a possibility to design such V-models, which are correct from the point of view of both the sampling and rendering, thus leading to both alias-free volumetric representation and alias-free rendered images. We performed numerous experiments with different combinations of V-models and reconstruction techniques. We have shown that the V-model with a Gaussian surface density profile combined with tricubic interpolation and Gabor derivative reconstruction outperforms the previously published technique with a linear density profile. This enables higher fidelity of images rendered from volume data due to increased sharpness of edges and thinner surface patches.", editor = "Hans Hagen", keywords = "Volume graphics, volume rendering, filter-based voxelization, normal estimation, error estimation.", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InCollection{EVL-1999-395, pages = "268--276", year = "1999", title = "Fast Iterative Refinement of Articulated Solid Dynamics", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-395", author = "Fran{\c{c}}ois Faure", abstract = "A new dynamics algorithm for articulated solid animation is presented. It provides enhancements of computational efficiency and accuracy control with respect to previous solutions. Iterative refinement allows us to perform interactive animations which could be only computed off-line using previous methods. The efficiency results from managing two sets of constraints associated with the kinematic graph, and proceeding in two steps. First, the acyclic constraints are solved in linear time. An iterative process then reduces the closed loop errors while maintaining the acyclic constraints. This allows the user to efficiently trade off accuracy for computation time. We analyze the complexity and investigate practical efficiency compared with other approaches. In contrast with previous research, we present a single method which is computationally efficient for acyclic bodies as well as for mesh-like bodies. The accuracy control is provided by the iterative improvement performed by the algorithm and also from the existence of two constraint priority levels induced by the method. Used in conjunction with a robust integration scheme, this new algorithm allows the interactive animation of scenes containing a few thousand geometric constraints, including closed loops. It has been successfully applied to real- time simulations.", editor = "Hans Hagen", keywords = "Dynamics, articulated bodies.", volume = "5 (3)", booktitle = "IEEE Transactions on Visualization and Computer Graphics", publisher = "IEEE Computer Society", } @InProceedings{EVL-1999-396, pages = "1--34", year = "1999", title = "Reflectance and texture of real-world surfaces", author = "Kristin J. Dana and Bram van Ginneken and Shree K. Nayar and Jan J. Koenderink", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-396", abstract = "In this work, we investigate the visual appearance of real-world surfaces and the dependence of appearance on the geometry of imaging conditions. We discuss a new texture representation called the BTF (bidirectional texture function) which captures the variation in texture with illumination and viewing direction. We present a BTF database with image textures from over 60 different samples, each observed with over 200 different combinations of viewing and illumination directions. We describe the methods involved in collecting the database as well as the importqance and uniqueness of this database for computer graphics. A related quantity to the BTF is the familiar BRDF (bidirectional reflectance distribution function). The measurement methods involved in the BTF database are conducive to simultaneous measurement of the BRDF. Accordingly, we also present a BRDF database with reflectance measurements for over 60 different samples, each observed with over 200 different combinations of viewing and illumination directions. Both of these unique databases are publicly available and have important implications for computer graphics.", volume = "18 (1)", keywords = "Intensity, color, photometry, thresholding, texture, physically based modeling, imaging geometry, radiometry,", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-397, pages = "35--55", year = "1999", title = "Combining constructive and equational geometric constraint-solving techniques", author = "R. Joan-Arinyo and A. Soto-Riera", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-397", abstract = "In the past few years, there has been a strong trend towards developing parametric, computer-aided design systems based on geometric constraint solving. An effective way to capture the design intent in these systems is to define relationships between geometric and technological variables. In general, geometric constraint solving including functional relationships requires a general approach and appropriate techniques to achieve the expected functional capabilities. This work reports on a hybrid method that combines two geometric constraint solving techniques: constructive and equational. The hybrid solver has the capability of managing functional relationships between dimension variables and variables representing conditions external to the geometric problem. The hybrid solver is described as a rewriting system and is shown to be correct.", volume = "18 (1)", keywords = "Canonical forms, constructive techniques, equational techniques, geometric constraint solving, rewriting systems", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-398, pages = "56--94", year = "1999", title = "Two methods for display of high contrast images", author = "Jack Tumblin and Jessica K. Hodgins and Brian K. Guenter", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-398", abstract = "High contrast images are common in night scenes and other scenes that include dark shadows and bright light sources. These scenes are difficult to display because their contrasts greatly exceed the range of most display devices for images. As a result, the image constrasts are compressed or truncated, obscuring subtle textures and details. Humans view and understand high contrast scenes easily, {"}adapting{"} their visual response to avoid compression or truncation with no apparent loss of detail. By imitating some of these visual adaptation processes, we developed methods for the improved display of high-contrast images. The first builds a display image from several layers of lighting and surface properties. Only the lighting layers are compressed, drastically reducing contrast while preserving much of the image detail. This method is practical only for synthetic images where the layers can be retained from the rendering process. The second method interactively adjusts the displayed image to preserve local contrasts in a small {"}foveal{"} neighborhood. Unlike the first method, this technique is usable on any image and includes a new tone reproduction operator. Both methods use a sigmoid function for contrast compression. This function has no effect when applied to small signals but compresses large signals to fit within an asymptotic limit. We demonstrate the effectiveness of these approaches by comparing processed and unprocessed images.", keywords = "Adaptation, adaption, tone reproduction, visual appearance", volume = "18 (1)", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-399, pages = "96--127", year = "1999", title = "Model and representation: the effect of visual feedback on human performance in a color picker interface", author = "Sarah A. Douglas and Arthur E. Kirkpatrick", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-399", abstract = "User interfaces for color selection consist of a visible screen representation, an input method, and the underlying conceptual organization of the color model. We report a two-way factorial, between-subjects variable experiment that tested the effect of high and low visual feedback interfaces on speed and accuracy of color matching for RGB and HSV color models. The only significant effect was improved accuracy due to increased visual feedback. Using color groups as a within-subjects variable, we found differences in performance of both speed and accuracy. We recommend that experimental tests adopt a color test set that does not show bias toward a particular model, but is based instead on a range of colors that would be most likely matched in practice by people using color selection software. We recomment the Macbeth Color Checker naturals, primaries, and grays. As a follow-up study, a qualitative case analysis of the way users navigated through the color space indicates that feedback helps users with limited knowledge of the model, allowing them to refine their match to a higher degree of accuracy. Users with very little or a lot of knowledge of the color model do not appear to be aided by increased feedback. In conclusion, we suggest that visual feedback and design of the interface may be a more important factor in improving the usability of a color selection interface than the particular color model used.", volume = "18 (2)", keywords = "HSV, RGB, color model, color selection, feedback, mental model, user interface", booktitle = "ACM Transactions on Graphics", } @Article{EVL-1999-4, year = "1999", title = "Active Vision for Complete Scene Reconstruction and Exploration", author = "{\'{E}}ric Marchand and Fran{\c{c}}ois Chaumette", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-4", language = "en", abstract = "This paper deals with the 3D structure estimation and exploration of static scenes using active vision. Our method is based on the structure from controlled motion approach that constrains camera motions to obtain an optimal estimation of the 3D structure of a geometrical primitive. Since this approach involves to gaze on the considered primitive, we have developed perceptual strategies able to perform a succession of robust estimations. This leads to a gaze planning strategy that mainly uses a representation of known and unknown areas as a basis for selecting viewpoints. This approach ensures a reconstruction as complete as possible of the scene.", month = jan, volume = "21", keywords = "3D reconstruction, scene exploration, purposive and active vision, perception strategies", number = "1", journal = "IEEE Transactions on Pattern Analysis and Machine Intelligence", } @Article{EVL-1999-40, pages = "65--90", year = "1999", title = "Using generic programming for designing a data structure for polyhedral surfaces", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-40", author = "Lutz Kettner", abstract = "Software design solutions are presented for combinatorial data structures, such as polyhedral surfaces and planar maps, tailored for program libraries in computational geometry. Design issues considered are flexibility, time and space efficiency, and ease-of-use. We focus on topological aspects of polyhedral surfaces and evaluate edge-based representations with respect to our design goals. A design for polyhedral surfaces in a halfedge data structure is developed following the generic programming paradigm known from the Standard Template Library STL for C++. Connections are shown to planar maps and face-based structures.", month = may, volume = "13", keywords = "Library design; Generic programming; Combinatorial data structure; Polyhedral surface; Halfedge data structure", number = "1", journal = "Computational Geometry", } @InProceedings{EVL-1999-400, pages = "128--170", year = "1999", title = "Fast and accurate hierarchical radiosity using global visibility", author = "Fr{\'{e}}do Durand and George Drettakis and Claude Puech", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-400", abstract = "Recent hierarchical global illumination algorithms permit the generation of images with a high degree of realism. Nonetheless, appropriate refinement of light transfers, high quality meshing, and accurate visibility calculation can be challenging tasks. This is particularly true for scenes containing multiple light sources and scenes lit mainly by indirect light. We present solutions to these problems by extending a global visibility data structure, the Visibility Skeleton. This extension allows us to calculate exact point-to-polygon form-factors at vertices created by subdivision. The structures also provides visibility information for all light interactions, allowing intelligent refinement strategies. High-quality meshing is effected based on a perceptualy based ranking strategy which results in appropriate insertions of discontinuity curves into the meshes representing illumination. We introduce a hierarchy of triangulations that allows the generation of a hierarchical radiosity solution using accurate visibility and meshing. Results of our implementation show that our new algorithm produces high quality view-independent lighting solutions for direct illumination, for scenes with multiple lights and also scenes lit mainly by indirect illumination.", volume = "18 (2)", keywords = "Discontinuity meshing, form factor calculation, global illumination, global visibility, hierarchical radiosity, hierarchical triangulation, perception", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-401, pages = "195--212", year = "1999", title = "Techniques for interactive design using the {PDE} method", author = "Hassan Ugail and Malcolm I. G. Bloor and Michael J. Wilson", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-401", abstract = "Interactive design of practical surfaces using the partial differential equation (PDE) method is considered. The PDE method treats surface design as a boundary value problem (ensuring that surfaces can be defined using a small set of design parameters). Owing to the elliptic nature of the PDE operator, the boundary conditions imposed around the edges of the surface control the internal shape of the surface. Moreover, surfaces obtained in this manner tend to be smooth and fair. The PDE chosen has a closed form solution allowing the interactive manipulation of the surfaces in real time. Thus we present efficient techniques by which we show how surfaces of practical significance can be constructed interactively in real time.", volume = "18 (2)", keywords = "CAD, PDE method, interactive design, partial differential equations", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-402, pages = "171--194", year = "1999", title = "Anisotropic diffusion for Monte Carlo noise reduction", author = "Michael D. McCool", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-402", abstract = "Monte Carlo sampling can be used to estimate solutions to global light transport and other rendering problems. However, a large number of observations may be needed to reduce the variance to acceptable levels. Rather than computing more observations within each pixel, if spatial coherence exists in image space it can be used to reduce visual error by averaging estimators in adjacent pixels. Anisotropic diffusion is a space-variant noise reduction technique that can selectively preserve texture, edges, and other details using a map of image coherence. The coherence map can be estimated from depth and normal information as well as interpixel color distance. Incremental estimation of the reduction in variance, in conjunction with statistical normalization of interpixel color distances, yields an energy-preserving algorithm that converges to a spatially nonconstant steady state.", volume = "18 (2)", keywords = "Monte Carlo methods, anisotropic diffusion, global illumination, image processing, image synthesis, light transport, noise reduction, space-variant filtering", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-403, pages = "213--256", year = "1999", title = "Radiance interpolants for accelerated bounded-error ray tracing", author = "Kavita Bala and Julie Dorsey and Seth Teller", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-403", abstract = "Ray tracers, which sample radiance, are usually regarded as offline rendering algorithms that are too slow for interactive use. In this article we present a system that exploits object-space, ray-space, image-space, and temporal coherence to accelerate ray tracing. Our system uses per-surface interpolants to approximate radiance both interactive and batch ray tracers. Our approach explicity decouples the two primary operations of a ray tracer--shading and visibility determination--and accelerates each of them independently. Shading is accelerated by quadrilinearily interpolating lazily acquired radiance samples. Interpolation error does not exceed a user-specified bound, allowing the user to control performance/quality tradeoffs. Error is bounded by adaptive sampling at discontinuities and radiance nonlinearities. Visibility determination at pixels is accelerated by reprojecting interpolants as the user's viewpoint changes. A fast scan-line alogoithm then achieves high performance without sacrificing image quality. For a smoothly varying viewpoint, the combination of lazy interpolants and projection substantially accelerates the ray tracer. Additionally, an efficient cache management algorithm keeps the memory footprint of the system small with negilgible overhead.", volume = "18 (3)", keywords = "4D interpolation, approximation, data structures, error bounds, interactive, interval arithmetic, radiance, rendering, rendering systems, visibility", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-404, pages = "257--277", year = "1999", title = "Analyzing bounding boxes for object intersection", author = "Subhash Suri and Philip M. Hubbard and John F. Hughes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-404", abstract = "Heuristics that exploit bouning boxes are common in algorithms for rendering, modeling, and animation. While experience has shown that bounding boxes improve the performance of these algorithms in practice, the previous theoretical analysis has concluded that bounding boxes perform poorly in the worst case. This paper reconciles this discrepancy by analyzing intersections among n geometric objects in terms of two parameters: an upper bound on the aspect ratio or elongatedness of each object; and an upper bound on the scale factor or size disparity between the largest and smallest objects. Letting Ko and Kb be the number of intersecting object pairs and bounding box pairs, respectively, we analyze a ratio measure of the bounding boxes' efficiency, r=Kb/n+Ko . The analysis proves that r=Oas log2s and r=Was .", volume = "18 (3)", keywords = "Aspect ratio, bounding boxes, collison detection", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-405, pages = "278--292", year = "1999", title = "Searchlight and Doppler effects in the visualization of special relativity: a corrected derivation of the transformation of radiance", author = "Daniel Weiskopf and Ute Kraus and Hanns Ruder", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-405", abstract = "We demonstrate that a photo-realistic image of a rapidly moving object is dominated by the searchlight and Doppler effects. Using a photon-counting technique, we derive expressions for the relativistic transformation of radiance. We show how to incorportate the Doppler and searchlight effects in the two common techniques of special relativistic visualization, namely ray tracing and polygon rendering. Most authors consider geometrical appearance only and neglect relativistic effects on the lighting model. Chang et al. [1996] present an incorrect derivation of the searchlight effect, which we compare to our results. Some examples are given to show the results of image synthesis with relativistic effects taken into account.", volume = "18 (3)", keywords = "Doppler effect, Lorentz transformation, aberration of light, illumination, searchlight effect, special relativity", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-406, pages = "293--315", year = "1999", title = "Modeling generalized cylinders via Fourier morphing", author = "Alberto S. Aguado and Eugenia Montiel and Ed Zaluska", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-406", abstract = "Generalized cylinders provide a compact representation for modeling many components of natural objects as well as a great variety of human-made industrial parts. This paper presents a new approach to modeling generalized cylinders based on cross-sectional curves defined using Fourier descriptors. This modeling is based on contour interpolation and is implemented using a subdivision technique. The definition of generalized cylinders uses a three-dimensional trajectory which provides an adequate control for the smoothness of bend with a small number of parameters and includes the orientation of each cross-section (i.e, the local coordinate system) in the interpolation framework. Fourier representations of cross-sectional curves are obtained from contours in digital images, and corresponding points are identified by considering angular and arc-length parametrizations. Changes in cross-section shape through the trajectory are performed using Fourier morphing. The technique proposed provides a comprehensive definition that allows the modeling of a wide variety of shapes, while maintaining a compact characterization to facilitate the description of shapes and displays.", volume = "18 (4)", keywords = "Fourier expansion, contour interpolation, generalized cylinders, morphing, parametric surfaces, solid modeling, subdivision methods", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-407, pages = "316--328", year = "1999", title = "A simple method for drawing a rational curve as two {B}{\'{e}}zier segments", author = "Jean Gallier", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-407", abstract = "In this paper we give a simple method for drawing a closed rational curve specified in terms of control points as two B{\'{e}}zier segments. The main result is the following: For every affine frame (r,s) (where rs), for every rational curve F(t) specified over [r,s] by some control polygon (0, ..., m) (where the zero are weighted control points or control vectors), the control points (0,... ,m (w.r.t.[r,s]) of the rational curve G(t) = F4t are given by qi=-1 ibi, where 4:RP1RP1 is the projectivity mapping [r,s] onto RP1]r,s]. Thus, in order to draw the entire trace of the curve F over -,+ , we simply draw the curve segments F[(r,s]) and G([r,s]). The correctness of the method is established using a simple geometric argument about ways of partitioning the real projective line into two disjoint segments. Other known methods for drawing rational curves can be justified using similar geometric arguments.", volume = "18 (4)", keywords = "B{\'{e}}zier curves, control points, de Casteljau algorithm, rational curves, subdivision, weights", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-408, pages = "329--360", year = "1999", title = "A unified approach for hierarchical adaptive tesselation of surfaces", author = "Luiz Velho and Luiz Henrique de Figueiredo and Jonas Gomes", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-408", abstract = "This paper introduces a unified and general tesselation algorithm for parametric and implicit surfaces. The algorithm produces a hierarchial mesh that is adapted to the surface geometry and has a multiresolution and progressive structure. The representation can be exploited with advantages in several applications.", volume = "18 (4)", keywords = "Adapted meshes, geometric modeling, implicit surfaces, multiresolution representations, parametric surfaces, polygonization, surface approximation", booktitle = "ACM Transactions on Graphics", } @InProceedings{EVL-1999-409, pages = "361--368", year = "1999", title = "The holodeck ray cache: an interactive rendering system for global illumination in nondiffuse environments", author = "Gregory Ward and Maryann Simmons", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-409", abstract = "We present a new method for rendering complex environments using interactive, progressive, view-independent, parallel ray tracing. A four-dimensional holodeck data structure serves as a rendering target and caching mechanism for interactive walk-throughs of nondiffuse environments with full global illumination. Ray sample density varies locally according to need, and on-demand ray computation is supported in a parallel implementation. The holodeck file is stored on disk and cached in memory by a server using a least-recently-used (LRU) beam-replacement strategy. The holodeck server coordinates separate ray evaluation and display processes, optimizing disk and memory usage. Different display systems are supported by specialized drivers, which handle display rendering, user interaction, and input. The display driver creates an image from ray samples sent by the server and permits the manipulation of local objects, which are rendered dynamically using approximate lighting computed from holodeck samples. The overall method overcomes many of the conventionl limits of interactive rendering in scenes with complex surface geometry and reflectance properties, through an effective combination of ray tracing, caching, and hardware rendering.", volume = "18 (4)", keywords = "Illumination, image reconstruction, mesh generation, ray tracing, rendering system, virtual reality", booktitle = "ACM Transactions on Graphics", } @Book{EVL-1999-41, year = "1999", title = "Computational Neuroscience: Trends in Research 1999", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-41", abstract = "This volume includes papers originally presented at the 7th annual Computational Neuroscience Meeting (CNS'98) held in July of 1998 at the Fess Parker Doubletree Inn in Santa Barbara, California. The CNS meetings bring together computational neuroscientists representing many different fields and backgrounds as well as many different experimental preparations and theoretical approaches. The papers published here range from pure experimental neurobiology, to neuro-ethology, mathematics, physics, and engineering. In all cases the research described is focused on understanding how nervous systems compute. The actual subjects of the research include a highly diverse number of preparations, modeling approaches, and analysis techniques. Accordingly, this volume reflects the breadth and depth of current research in computational neuroscience taking place throughout the world.", editor = "J. M. Bower", publisher = "Elsevier Science", } @InProceedings{EVL-1999-410, year = "1999", title = "A Graph Theoretic Approach to {CAD} for the Analysis of Planar Mechanisms", author = "K. T. Hong and Y. T. Lang", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-410", abstract = "One of the main goals of multibody dynamics research is to develop formulations that automatically derive the equations of motions for complex mechanical systems. Equations of motion are formulated systematically and then solved numerically. This paper studies analytic methods for formulating the equation of motions, with emphasis on the graph theoretic modelling approach. The graph theoretic approach is proposed for modelling and analysis of planar mechanical systems. The development of the CAD system incorporating graph theoretic models would be used for mechanical analysis. A graphical user interface will be used to capture the design and to display the solutions of the dynamic and kinematic computations. Throughout the analysis, the CAD tool ( PMech) would be useful for relieving the engineer's task of doing the calculations by hand, the result of kinematic and dynamic analysis of the different prototypes constitutes the graphical display of the mechanism, enhancing the engineer's understanding of the mechanical behaviour under consideration.", editor = "V. Skala", keywords = "CAD, computer graphics, constraint motion, graph theory, simulation.", booktitle = "WSCG'99 Conference Proceedings", } @InProceedings{EVL-1999-411, year = "1999", title = "On a Fundamental Physical Principle Underlying the Point Location Algorithm in Computer Graphics", author = "Sumit Ghosh", URL = "http://visinfo.zib.de/EVlib/Show?EVL-1999-411", abstract = "The issue of point location is an important problem in computer graphics and the study of efficient data structures and fast algorithms is an important research area for both computer graphics and computational geometry disciplines. When filling the interior region of a planar polygon in computer graphics, it is necessary to identify all points that lie within the interior region and those that are outside. Sutherland and Hodgman are credited for designing the first algorithm to solve the problem. Their approach utilizes vector construction and vector cross products, and forms the basis of the {"}odd parity{"} rule. To verify whether a test point is within or outside a given planar polygon, a ray from the test point is drawn extending to infinity in any direction without intersecting a vertex. If the ray intersects the polygon outline an odd number of times, the region is considered interior. Otherwise, the point is outside the region. In 3 dimensional space, Lee and Preparata propose an algorithm but their approach is limited to point location relative to convex polyhedrons with vertices in 3D-space. Although it is rich on optimal data structures to reduce the storage requirement and efficient algorithms for fast execution, a proof of correctness of the algorithm, applied to the general problem of point location relative to any arbitrary surface in 3D-space, is absent in the literature. This paper argues that the electromagnetic field theory and Gauss's Law constitute a fundamental basis for the {"}odd parity{"} rule and shows that the {"}odd parity{"} rule may be correctly extended to point location relative to any arbitrary closed surface in