Issue 3

Permanent URI for this collection

https://diglib7.eg.org/handle/10.2312/86
EG 1998 Conference Proceedings

BibTeX (Issue 3)
                
@article{
10.1111:1467-8659.00243,

journal = {Computer Graphics Forum},
title = {{
Preface}},

author = {
Ferreira, F.
 and 
Goebel, Martin
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00243}

}
                
@article{
10.1111:1467-8659.00254,

journal = {Computer Graphics Forum},
title = {{
A Light Hierarchy for Fast Rendering of Scenes with Many Lights}},

author = {
Paquette, Eric
 and 
Poulin, Pierre
 and 
Drettakis, George
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00254}

}
                
@article{
10.1111:1467-8659.00252,

journal = {Computer Graphics Forum},
title = {{
Egocentric Object Manipulation in Virtual Environments: Empirical Evaluation of Interaction Techniques}},

author = {
Poupyrev, I.
 and 
Ichikawa, T.
 and 
Weghorst, S.
 and 
Billinghurst, M.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00252}

}
                
@article{
10.1111:1467-8659.00253,

journal = {Computer Graphics Forum},
title = {{
A Collaborative Scene Editor for VRML Worlds}},

author = {
Lu, Tain-chi
 and 
Chiang, Chuanwen
 and 
Lin, Ming-tang
 and 
Lee, Chungnan
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00253}

}
                
@article{
10.1111:1467-8659.00257,

journal = {Computer Graphics Forum},
title = {{
Importance Driven Texture Coordinate Optimization}},

author = {
Sloan, Peter-Pike J.
 and 
Weinstein, David M.
 and 
Brederson, J.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00257}

}
                
@article{
10.1111:1467-8659.00256,

journal = {Computer Graphics Forum},
title = {{
Anisotropic Solid Texture Synthesis Using Orthogonal 2D Views}},

author = {
Dischler, J.M.
 and 
Ghazanfarpour, D.
 and 
Freydier, R.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00256}

}
                
@article{
10.1111:1467-8659.00255,

journal = {Computer Graphics Forum},
title = {{
Optical Flow Rendering}},

author = {
Park, Tae-Joon
 and 
Shin, Sung Yong
 and 
Lee, Seungyong
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00255}

}
                
@article{
10.1111:1467-8659.00260,

journal = {Computer Graphics Forum},
title = {{
Progressive Iso-Surface Extraction from Hierarchical 3D Meshes}},

author = {
Grosso, Roberto
 and 
Ertl, Thomas
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00260}

}
                
@article{
10.1111:1467-8659.00259,

journal = {Computer Graphics Forum},
title = {{
Maximum Intensity Projection Using Splatting in Sheared Object Space}},

author = {
Cai, Wenli
 and 
Sakas, Georgios
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00259}

}
                
@article{
10.1111:1467-8659.00261,

journal = {Computer Graphics Forum},
title = {{
Multiresolution Isosurface Extraction with Adaptive Skeleton Climbing}},

author = {
Poston, Tim
 and 
Wong, Tien-Tsin
 and 
Heng, Pheng-Ann
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00261}

}
                
@article{
10.1111:1467-8659.00258,

journal = {Computer Graphics Forum},
title = {{
Simulating Wood Using a Voxel Approach}},

author = {
Buchanan, John W.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00258}

}
                
@article{
10.1111:1467-8659.00262,

journal = {Computer Graphics Forum},
title = {{
A Vector Approach for Global Illumination in Ray Tracing}},

author = {
Zaninetti, Jacques
 and 
Serpaggi, Xavier
 and 
Peroche, Bernard
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00262}

}
                
@article{
10.1111:1467-8659.00244,

journal = {Computer Graphics Forum},
title = {{
Author Index}},

author = {},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00244}

}
                
@article{
10.1111:1467-8659.00263,

journal = {Computer Graphics Forum},
title = {{
A Two-Pass Hardware-Based Method for Hierarchical Radiosity}},

author = {
Martin, I.
 and 
Pueyo, X.
 and 
Tost, D.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00263}

}
                
@article{
10.1111:1467-8659.00266,

journal = {Computer Graphics Forum},
title = {{
Accelerated Walkthroughs of Virtual Environments Based on Visibility Preprocessing and Simplification}},

author = {
Wang, Yigang
 and 
Bao, Hujun
 and 
Peng, Qunsheng
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00266}

}
                
@article{
10.1111:1467-8659.00264,

journal = {Computer Graphics Forum},
title = {{
Getting Rid of Links in Hierarchical Radiosity}},

author = {
Stamminger, M.
 and 
Schirmacher, H.
 and 
Slusallek, Ph.
 and 
Seidel, H.-P.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00264}

}
                
@article{
10.1111:1467-8659.00265,

journal = {Computer Graphics Forum},
title = {{
Screen-Space Constraints for Camera Movements: the Virtual Cameraman}},

author = {
Jardillier, Frank
 and 
Languenou, Eric
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00265}

}
                
@article{
10.1111:1467-8659.00268,

journal = {Computer Graphics Forum},
title = {{
Importance Driven Halftoning}},

author = {
Streit, L.
 and 
Buchanan, J.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00268}

}
                
@article{
10.1111:1467-8659.00267,

journal = {Computer Graphics Forum},
title = {{
Space Discretization for Efficient Human Navigation}},

author = {
Bandi, Srikanth
 and 
Thalmann, Daniel
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00267}

}
                
@article{
10.1111:1467-8659.00269,

journal = {Computer Graphics Forum},
title = {{
Dithered Color Quantization}},

author = {
Buhmann, J. M.
 and 
Fellner, Dieter W.
 and 
Held, M.
 and 
Ketterer, J.
 and 
Puzicha, J.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00269}

}
                
@article{
10.1111:1467-8659.00270,

journal = {Computer Graphics Forum},
title = {{
Perception Based Color Image Difference}},

author = {
Neumann, Laszlo
 and 
Matkovic, Kresimir
 and 
Purgathofer, Werner
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00270}

}
                
@article{
10.1111:1467-8659.00245,

journal = {Computer Graphics Forum},
title = {{
Frontiers in User-Computer Interaction}},

author = {
Van Dam, Andries
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00245}

}
                
@article{
10.1111:1467-8659.00271,

journal = {Computer Graphics Forum},
title = {{
Conservative Visibility and Strong Occlusion for Viewspace Partitioning of Densely Occluded Scenes}},

author = {
Cohen-Or, Daniel
 and 
Fibich, Gadi
 and 
Halperin, Dan
 and 
Zadicario, Eyal
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00271}

}
                
@article{
10.1111:1467-8659.00273,

journal = {Computer Graphics Forum},
title = {{
Molecular Dynamics Simulation in Virtual Environments}},

author = {
Ai, Z.
 and 
Frohlich, T.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00273}

}
                
@article{
10.1111:1467-8659.00272,

journal = {Computer Graphics Forum},
title = {{
Using Wavefront Tracing for the Visualization and Optimization of Progressive Lenses}},

author = {
Loos, J.
 and 
Slusallek, Ph.
 and 
Seidel, H.-P.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00272}

}
                
@article{
10.1111:1467-8659.00275,

journal = {Computer Graphics Forum},
title = {{
A Bernstein-Bezier Based Approach to Soft Tissue Simulation}},

author = {
Roth, S.H.
 and 
Gross, Markus H.
 and 
Turello, Silvio
 and 
Carls, Friedrich R.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00275}

}
                
@article{
10.1111:1467-8659.00278,

journal = {Computer Graphics Forum},
title = {{
Rapid and Accurate Contact Determination between Spline Models using ShellTrees}},

author = {
Krishnan, S.
 and 
Gopi, M.
 and 
Lin, M.
 and 
Manocha, D.
 and 
Pattekar, A.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00278}

}
                
@article{
10.1111:1467-8659.00277,

journal = {Computer Graphics Forum},
title = {{
Subdivision Schemes for Thin Plate Splines}},

author = {
Weimer, Henrik
 and 
Warren, Joe
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00277}

}
                
@article{
10.1111:1467-8659.00274,

journal = {Computer Graphics Forum},
title = {{
Real-time Biomechanically-based Muscle Volume Deformation using FEM}},

author = {
Zhu, Qing-hong
 and 
Chen, Yan
 and 
Kaufman, Arie
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00274}

}
                
@article{
10.1111:1467-8659.00276,

journal = {Computer Graphics Forum},
title = {{
Emotion Editing using Finite Elements}},

author = {
Koch, Rolf M.
 and 
Gross, Markus H.
 and 
Bosshard, Albert A.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00276}

}
                
@article{
10.1111:1467-8659.00279,

journal = {Computer Graphics Forum},
title = {{
A New Approach for Direct Manipulation of Free-Form Curve}},

author = {
Zheng, J.M.
 and 
Chan, K.W.
 and 
Gibson, I.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00279}

}
                
@article{
10.1111:1467-8659.00281,

journal = {Computer Graphics Forum},
title = {{
Mass-Spring Simulation using Adaptive Non-Active Points}},

author = {
Howlett, P.
 and 
Hewitt, W.T.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00281}

}
                
@article{
10.1111:1467-8659.00280,

journal = {Computer Graphics Forum},
title = {{
An Enhanced Spring Model for Information Visualization}},

author = {
Theisel, Holger
 and 
Kreuseler, Matthias
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00280}

}
                
@article{
10.1111:1467-8659.00246,

journal = {Computer Graphics Forum},
title = {{
The Convergence of Graphics and Imaging}},

author = {
Foley, James D.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00246}

}
                
@article{
10.1111:1467-8659.00282,

journal = {Computer Graphics Forum},
title = {{
The Art of Knitted Fabrics, Realistic & Physically Based Modelling Of Knitted Patterns}},

author = {
Meißner, M.
 and 
Eberhardt, B.
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00282}

}
                
@article{
10.1111:1467-8659.00247,

journal = {Computer Graphics Forum},
title = {{
Anno 2010 - Remembering Our Future: Challenges and Frontiers of Human-Media Technology as the Kernel for Human-Centered Computing}},

author = {
Encarnacao, Jose
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00247}

}
                
@article{
10.1111:1467-8659.00283,

journal = {Computer Graphics Forum},
title = {{
Colour Illustrations}},

author = {},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00283}

}
                
@article{
10.1111:1467-8659.00249,

journal = {Computer Graphics Forum},
title = {{
Fast Feature-Based Metamorphosis and Operator Design}},

author = {
Lee, Tong-Yee
 and 
Lin, Young-Ching
 and 
Sun, Y.N.
 and 
Lin, Leeween
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00249}

}
                
@article{
10.1111:1467-8659.00248,

journal = {Computer Graphics Forum},
title = {{
Animation of Biological Organ Growth Based on L-systems}},

author = {
Durikovic, Roman
 and 
Kaneda, Kazufumi
 and 
Yamashita, Hideo
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00248}

}
                
@article{
10.1111:1467-8659.00250,

journal = {Computer Graphics Forum},
title = {{
Interactive 3D Morphing}},

author = {
Bao, Hujun
 and 
Peng, Qunsheng
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00250}

}
                
@article{
10.1111:1467-8659.00251,

journal = {Computer Graphics Forum},
title = {{
A Framework for Synchronized Editing of Multiple Curve Representations}},

author = {
Grimm, Cindy
 and 
Ayers, Matthew
},
year = {
1998},

publisher = {
Blackwell Publishers Ltd and the Eurographics Association},


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.00251}

}

Browse

Recent Submissions

Now showing 1 - 41 of 41
  • No Thumbnail Available
    Item
    Preface
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Ferreira, F.; Goebel, Martin
  • No Thumbnail Available
    Item
    A Light Hierarchy for Fast Rendering of Scenes with Many Lights
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Paquette, Eric; Poulin, Pierre; Drettakis, George
    We introduce a new data structure in the form of a light hierarchy for efficiently ray-tracing scenes with many light sources. An octree is constructed with the point light sources in a scene. Each node represents all the light sources it contains by means of a virtual light source. We determine bounds on the error committed with this approximation to shade a point, both for the cases of diffuse and specular reflections. These bounds are then used to guide a hierarchical shading algorithm. If the current level of the light hierarchy provides shading of sufficient quality, the approximation is used, thus avoiding the cost of shading for all the light sources contained below this level. Otherwise the descent into the light hierarchy continues.Our approach has been implemented for scenes without occlusion. The results show important acceleration compared to standard ray-tracing (up to 90 times faster) and an important improvement compared to Wardâ s adaptive shadow testing.
  • No Thumbnail Available
    Item
    Egocentric Object Manipulation in Virtual Environments: Empirical Evaluation of Interaction Techniques
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Poupyrev, I.; Ichikawa, T.; Weghorst, S.; Billinghurst, M.
    The acceptance of virtual environment (VE) technology requires scrupulous optimization of the most basic interactions in order to maximize user performance and provide efficient and enjoyable virtual interfaces. Motivated by insufficient understanding of the human factors design implications of interaction techniques and tools for virtual interfaces, this paper presents results of a formal study that compared two basic interaction metaphors for egocentric direct manipulation in VEs, virtual hand and virtual pointer, in object selection and positioning experiments. The goals of the study were to explore immersive direct manipulation interfaces, compare performance characteristics of interaction techniques based on the metaphors of interest, understand their relative strengths and weaknesses, and derive design guidelines for practical development of VE applications.
  • No Thumbnail Available
    Item
    A Collaborative Scene Editor for VRML Worlds
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Lu, Tain-chi; Chiang, Chuanwen; Lin, Ming-tang; Lee, Chungnan
    In this paper, we analyze the requirements for a Web-based collaborative infrastructure within a virtual world. Additionally, we combine several tools and methodologies to propose a flexible and fluid collaborative environment using Java language to create a VRML scene graph. The proposed prototype aims at four aspects: a shared workspace of scene editor, an active entity composition algorithm in Java, collaborative control in the multi-user environment, and access control mechanism toward the shared data.
  • No Thumbnail Available
    Item
    Importance Driven Texture Coordinate Optimization
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Sloan, Peter-Pike J.; Weinstein, David M.; Brederson, J.
    Traditionally, texture coordinates have been generated based solely on the modelâ s geometry, often even before a modelâ s textures have been created. With the arrival of new technologies, such as 3D paint programs, weaknesses of a static optimization pre-process are becoming apparent. These weaknesses arise from constructing a parameterization based solely on the modelâ s geometry, ignoring the fact that detail is not uniformly spaced throughout the texture space. In fact, certain regions of the texture are more important than other regions. In this paper we introduce the notion of the "importance map" and describe how importance values are derived from both intrinsic properties of the texture and user-guided highlights. Furthermore, we describe how importance maps are used to drive the texture coordinate optimization. Finally, we show how this optimization process can be integrated into a 3D painting environment, enabling periodic optimization at any stage of texture design.
  • No Thumbnail Available
    Item
    Anisotropic Solid Texture Synthesis Using Orthogonal 2D Views
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Dischler, J.M.; Ghazanfarpour, D.; Freydier, R.
    Analytical approaches, based on digitised 2D texture models, for an automatic solid (3D) texture synthesis have been recently introduced to Computer Graphics. However, these approaches cannot provide satisfactory solutions in the usual case of natural anisotropic textures (wood grain for example). Indeed, solid texture synthesis requires particular care, and sometimes external knowledge to "guess" the internal structure of solid textures because only 2D texture models are used for analysis. By making some basic assumptions about the internal structure of solid textures, we propose a very efficient method based on a hybrid analysis (spectral and histogram) for an automatic synthesis of solid textures. This new method allows us to obtain high precision solid textures (closely resembling initial models) in a large number of cases, including the difficult case of anisotropic textures.
  • No Thumbnail Available
    Item
    Optical Flow Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Park, Tae-Joon; Shin, Sung Yong; Lee, Seungyong
    This paper proposes a new approach to image-based rendering that generates an image viewed from an arbitrary camera position and orientation by rendering optical flows extracted from reference images. To derive valid optical flows, we develop an analysis technique that improves the quality of stereo matching. Without using any special equipments such as range cameras, this technique constructs reliable optical flows from a sequence of matching results between reference images. We also derive validity conditions of optical flows and show that the obtained flows satisfy those conditions. Since environment geometry is inferred from the optical flows, we are able to generate more accurate images with this additional geometric information. Our approach makes it possible to combine an image rendered from optical flows with an image generated by a conventional rendering technique through a simple Z-buffer algorithm.
  • No Thumbnail Available
    Item
    Progressive Iso-Surface Extraction from Hierarchical 3D Meshes
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Grosso, Roberto; Ertl, Thomas
    A multiresolution data decomposition offers a fundamental framework supporting compression, progressive transmission, and level-of-detail (LOD) control for large two or three dimensional data sets discretized on complex meshes. In this paper we extend a previously presented algorithm for 3D mesh reduction for volume data based on multilevel finite element approximations in two ways. First, we present efficient data structures which allow to incrementally construct approximations of the volume data at lower or higher resolutions at interactive rates. An abstract description of the mesh hierarchy in terms of a coarse base mesh and a set of integer records offers a high compression potential which is essential for an efficient storage and a progressive network transmission. Based on this mesh hierarchy we then develop a new progressive iso-surface extraction algorithm. For a given iso-value, the corresponding iso-surface can be computed at different levels of resolution. Changing to a higher or coarser resolution will update the surface only in those regions where the volume data is being refined or coarsened. Our approach allows to interactively visualize very large scalar fields like medical data sets, whereas the conventional algorithms would have required at least an order of magnitude more resources.
  • No Thumbnail Available
    Item
    Maximum Intensity Projection Using Splatting in Sheared Object Space
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Cai, Wenli; Sakas, Georgios
    In this paper we present a new Maximum Intensity Projection (MIP) algorithm which was implemented employing splatting in a shear-warp context. This algorithm renders a MIP image by first splatting each voxel on two intermediate spaces called "worksheet" and "shear image". Then, the maximum value is evaluated between worksheet and shear image. Finally, shear image is warped on the screen to generate the result image. Different footprints implementing different quality modes are discussed. In addition, we introduced a line encoded indexing speed-up method to obtain interactive speed. This algorithm allows for a quantitative, predictable trade-off between interactivity and image quality.
  • No Thumbnail Available
    Item
    Multiresolution Isosurface Extraction with Adaptive Skeleton Climbing
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Poston, Tim; Wong, Tien-Tsin; Heng, Pheng-Ann
    An isosurface extraction algorithm which can directly generate multiresolution isosurfaces from volume data is introduced. It generates low resolution isosurfaces, with 4 to 25 times fewer triangles than that generated by marching cubes algorithm, in comparable running times. By climbing from vertices (0-skeleton) to edges (1-skeleton) to faces (2-skeleton), the algorithm constructs boxes which adapt to the geometry of the true isosurface. Unlike previous adaptive marching cubes algorithms, the algorithm does not suffer from the gap-filling problem. Although the triangles in the meshes may not be optimally reduced, it is much faster than postprocessing triangle reduction algorithms. Hence the coarse meshes it produces can be used as the initial starts for the mesh optimization, if mesh optimality is the main concern.
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    Simulating Wood Using a Voxel Approach
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Buchanan, John W.
    In this paper we present a technique for generating three-dimensional wood textures using a regular texture array. Currently three-dimensional wood textures are generated using procedural textures. Procedural textures are flexible and require little memory, however the modeling of local artifacts such as knots is difficult using the procedural approach. By representing the wood as a texture array and growing the wood in this array we can easily simulate local phenomena such as knots. Our growth model is an approximation to the biological model and assumes that there are several similar wood cells per array element. This means that we can model artifacts that are defined by groups of similar cells. In particular our model is well suited for the modeling of soft-woods.
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    A Vector Approach for Global Illumination in Ray Tracing
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Zaninetti, Jacques; Serpaggi, Xavier; Peroche, Bernard
    This paper presents a method taking global illumination into account in a ray tracing environment. A vector approach is introduced, which allows to deal with all the types of light paths and the directional properties of materials. Three types of vectors are defined: Direct Light Vectors associated to light sources, Indirect Light Vectors which correspond to light having been diffusely reflected at least once and Caustic Light Vectors which are associated to light rays emitted by sources and reflected and/or transmitted by specular surfaces. These vectors are estimated at a small number of points in the scene. A weighted interpolation between known values allows to reconstruct these vectors for the other points, with the help of a gradient computation for the indirect component. This approach also allows to take uniform area light sources (spherical, rectangular and circular) into account for all the types of vectors. Computed images are thus more accurate and no discretizing of the geometry of the scene is needed.
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    Author Index
    (Blackwell Publishers Ltd and the Eurographics Association, 1998)
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    A Two-Pass Hardware-Based Method for Hierarchical Radiosity
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Martin, I.; Pueyo, X.; Tost, D.
    Finite elements methods for radiosity are aimed at computing global illumination solutions efficiently. However these methods are not suitable for obtaining high quality images due to the lack of error control. Two-pass methods allow to achieve that level of quality computing illumination at each pixel and thus introducing a high computing overhead. We present a two-pass method for radiosity that allows to produce high quality images avoiding most of the per-pixel computations. The method computes a coarse hierarchical radiosity solution and then performs a second pass using current graphics hardware accelerators to generate illumination as high definition textures.
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    Accelerated Walkthroughs of Virtual Environments Based on Visibility Preprocessing and Simplification
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Wang, Yigang; Bao, Hujun; Peng, Qunsheng
    This paper proposes a new preprocessing method for interactive rendering of complex polygonal virtual environments. The approach divides the space that observer can reach into many rectangular viewpoint regions. For each region, an outer rectangular volume (ORV) is established to surround it. By adaptively partitioning the boundary of the ORV together with the viewpoint region, all the rays that originate from the viewpoint region are divided into the beams whose potentially visible polygon number is less than a preset threshold. If a resultant beam is the smallest and intersects many potentially visible polygons, the beam is simplified as a fixed number of rays and the averaged color of the hit polygons is recorded. For other beams, their potentially visible sets (PVS) of polygons are stored respectively. During an interactive walkthrough, the visual information related to the current viewpoint is retrieved from the storage. The view volume clipping, visibility culling and detail simplification are efficiently supported by these stored data. The rendering time is independent of the scene complexity.
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    Getting Rid of Links in Hierarchical Radiosity
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Stamminger, M.; Schirmacher, H.; Slusallek, Ph.; Seidel, H.-P.
    Hierarchical radiosity with clustering has positioned itself as one of the most efficient algorithms for computing global illumination in non-trivial environments. However, using hierarchical radiosity for complex scenes is still problematic due to the necessity of storing a large number of transport coefficients between surfaces in the form of links. In this paper, we eliminate the need for storage of links through the use of a modified shooting method for solving the radiosity equation. By distributing only unshot radiosity in each step of the iteration, the number of links decreases exponentially. Recomputing these links instead of storing them increases computation time, but reduces memory consumption dramatically. Caching may be used to reduce the time overhead. We analyze the error behavior of the new algorithm in comparison with the normal gathering approach for hierarchical radiosity. In particular, we consider the relation between the global error of a hierarchical radiosity solution and the local error threshold for each link.
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    Screen-Space Constraints for Camera Movements: the Virtual Cameraman
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Jardillier, Frank; Languenou, Eric
    This article presents a virtual cameraman which allows us to obtain the whole set of camera movements satisfying user defined constraints specified in the image space and/or constraints on the objects of the scene. This research follows the "Declarative Modelling" approach, which focuses on a 3-phase modeller concept: description; generation; result exploration.Our tool is based on a solver using interval arithmetic. The time dimension is treated as another variable, thus constraints can be specified for the total duration of the animation or could last only for a given amount of time. There is no keyframing and no interpolation, thereby, for the solutions obtained, the satisfaction of the specified constraints are guaranteed. Several ways to include time dimension efficiently are discussed.We claim that the method is simple enough to be implemented easily without the need of any external solver.
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    Importance Driven Halftoning
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Streit, L.; Buchanan, J.
    Most halftoning techniques have been primarily concerned with achieving an accurate reproduction of local gray-scale intensities while avoiding the introduction of artifacts. A secondary concern in halftoning has been the preservation of edges in the halftoned image. In this paper, we will introduce a new halftoning technique that utilizes a bandpass pyramid to achieve an accurate reproduction of important attributes in the image. Ink is distributed through the bandpass pyramid primarily according to a user defined importance function. This technique has three main characteristics. First, our technique can produce results similar to many other halftoning techniques by allowing a generic importance function to be specified. If the chosen importance function is average intensity we obtain results similar to traditional halftoning. We also show how the importance function can be changed to highlight areas with high variance. Second, in addition to changing the importance function, the drawing primitives can also be changed. By using line segments instead of single pixels as drawing primitives we illustrate how edge enhancement can be achieved. Third, this technique allows the user to easily limit the number drawing primitives used. This is useful in limited resource rendering.In addition to providing a tailorable halftoning technique our method can easily be adapted to produce two tone non-photorealistic (NPR) images. We illustrate this by showing how sketched effects can be achieved by aligning the drawing primitives according to different image attributes.
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    Space Discretization for Efficient Human Navigation
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Bandi, Srikanth; Thalmann, Daniel
    There is a large body of research on motion control of legs in human models. However, they require specification of global paths in which to move. A method for automatically computing a global motion path for a human in 3D environment of obstacles is presented. Object space is discretized into a 3D grid of uniform cells and an optimal path is generated between two points as a discrete cell path. The grid is treated as graph with orthogonal links of uniform cost. A' search method is applied for path finding. By considering only the cells on the upper surface of objects on which human walks, a large portion of the grid is discarded from the search space, thus boosting efficiency. This is expected to be a higher level mechanism for various local foot placement methods in human animation.
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    Dithered Color Quantization
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Buhmann, J. M.; Fellner, Dieter W.; Held, M.; Ketterer, J.; Puzicha, J.
    Image quantization and digital halftoning are fundamental problems in computer graphics, which arise when displaying high-color images on non-truecolor devices. Both steps are generally performed sequentially and, in most cases, independent of each other. Color quantization with a pixel-wise defined distortion measure and the dithering process with its local neighborhood optimize different quality criteria or, frequently, follow a heuristic without reference to any quality measure.In this paper we propose a new method to simultaneously quantize and dither color images. The method is based on a rigorous cost-function approach which optimizes a quality criterion derived from a generic model of human perception. A highly efficient algorithm for optimization based on a multiscale method is developed for the dithered color quantization cost function. The quality criterion and the optimization algorithms are evaluated on a representative set of artificial and real-world images as well as on a collection of icons. A significant image quality improvement is observed compared to standard color reduction approaches.
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    Perception Based Color Image Difference
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Neumann, Laszlo; Matkovic, Kresimir; Purgathofer, Werner
    A good image metric is often needed in digital image synthesis. It can be used to check the convergence behavior in progressive methods, to compare images rendered using various rendering methods etc. Since images are rendered to be observed by humans, an image metric should correspond to human perception as well. We propose here a new algorithm which operates in the original image space. There is no need for Fourier or wavelet transforms. Furthermore, the new metric is view distance dependent. The new method uses the contrast sensitivity function. The main idea is to place a number of various rectangles in images, and to compute the CIE LUV average color difference between corresponding rectangles. Errors are then weighted according to the rectangle size and the contrast sensitivity function.
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    Frontiers in User-Computer Interaction
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Van Dam, Andries
    In this age of (near-)adequate computing power, the power and usability of the user interface is as key to an applicationâ s success as its functionality. Most of the code in modern desktop productivity applications resides in the user interface. But despite its centrality, the user interface field is currently in a rut: the WIMP (Windows, Icons, Menus, Point-and-Click GUI based on keyboard and mouse) has evolved little since it was pioneered by Xerox PARC in the early â 70s. Computer and display form factors will change dramatically in the near future and new kinds of interaction devices will soon become available. Desktop environments will be enriched not only with PDAs such as the Newton and Palm Pilot, but also with wearable computers and large-screen displays produced by new projection technology, including office-based immersive virtual reality environments. On the input side, we will finally have speech-recognition and force-feedback devices. Thus we can look forward to user interfaces that are dramatically more powerful and better matched to human sensory capabilities than those dependent solely on keyboard and mouse. 3D interaction widgets controlled by mice or other interaction devices with three or more degrees of freedom are a natural evolution from their two-dimensional WIMP counterparts and can decrease the cognitive distance between widget and task for many tasks that are intrinsically 3D, such as scientific visualization and MCAD. More radical post-WIMP UIs are needed for immersive virtual reality where keyboard and mouse are absent. Immersive VR provides good driving applications for developing post-WIMP UIs based on multimodal interaction that involve more of our senses by combining the use of gesture, speech, and haptics.
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    Conservative Visibility and Strong Occlusion for Viewspace Partitioning of Densely Occluded Scenes
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Cohen-Or, Daniel; Fibich, Gadi; Halperin, Dan; Zadicario, Eyal
    Computing the visibility of out-door scenes is often much harder than of in-door scenes. A typical urban scene, for example, is densely occluded, and it is effective to precompute its visibility space, since from a given point only a small fraction of the scene is visible. The difficulty is that although the majority of objects are hidden, some parts might be visible at a distance in an arbitrary location, and it is not clear how to detect them quickly. In this paper we present a method to partition the viewspace into cells containing a conservative superset of the visible objects. For a given cell the method tests the visibility of all the objects in the scene. For each object it searches for a strong occluder which guarantees that the object is not visible from any point within the cell. We show analytically that in a densely occluded scene, the vast majority of objects are strongly occluded, and the overhead of using conservative visibility (rather than visibility) is small. These results are further supported by our experimental results. We also analyze the cost of the method and discuss its effectiveness.
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    Molecular Dynamics Simulation in Virtual Environments
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Ai, Z.; Frohlich, T.
    A virtual environment for interactive molecular dynamics simulation has been designed and implemented at the Fraunhofer Institute for Computer Graphics. Different kinds of virtual reality devices are used in the environment for immersive display and interaction with the molecular system. A parallel computer is used to simulate the physical and chemical properties of the molecular system dynamically. A high-speed network exchanges data between the simulation program and the modeling program. Molecular dynamics simulation virtual environment provides scientists with a powerful tool to study immersively the world of molecules. The dynamic interaction between an AIDS antiviral drug and reverse transcriptase enzyme is illustrated in the paper.
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    Using Wavefront Tracing for the Visualization and Optimization of Progressive Lenses
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Loos, J.; Slusallek, Ph.; Seidel, H.-P.
    Progressive addition lenses are a relatively new approach to compensate for defects of the human visual system. While traditional spectacles use rotationally symmetric lenses, progressive lenses require the specification of free-form surfaces. This poses difficult problems for the optimal design and its visual evaluation.This paper presents two new techniques for the visualization of optical systems and the optimization of progressive lenses. Both are based on the same wavefront tracing approach to accurately evaluate the refraction properties of complex optical systems.We use the results of wavefront tracing for continuously re-focusing the eye during rendering. Together with distribution ray tracing, this yields high-quality images that accurately simulate the visual quality of an optical system. The design of progressive lenses is difficult due to the trade-off between the desired properties of the lens and unavoidable optical errors, such as astigmatism and distortions. We use wavefront tracing to derive an accurate error functional describing the desired properties and the optical error across a lens. Minimizing this error yields optimal free-form lens surfaces.While the basic approach is much more general, in this paper, we describe its application to the particular problem of designing and evaluating progressive lenses and demonstrate the benefits of the new approach with several example images.
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    A Bernstein-Bezier Based Approach to Soft Tissue Simulation
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Roth, S.H.; Gross, Markus H.; Turello, Silvio; Carls, Friedrich R.
    This paper discusses a Finite Element approach for volumetric soft tissue modeling in the context of facial surgery simulation. We elaborate on the underlying physics and address some computational aspects of the finite element discretization.In contrast to existing approaches speed is not our first concern, but we strive for the highest possible accuracy of simulation. We therefore propose an extension of linear elasticity towards incompressibility and nonlinear material behavior, in order to describe the complex properties of human soft tissue more accurately. Furthermore, we incorporate higher order interpolation functions using a Bernstein-Bezier formulation, which has various advantageous properties, such as its integral polynomial form of arbitrary degree, efficient subdivision schemes, and suitability for geometric modeling and rendering. In addition, the use of tetrahedral Finite Elements does not put any restriction on the geometry of the simulated volumes.Experimental results obtained from a synthetic block of soft tissue and from the Visible Human Data Set illustrate the performance of the envisioned model.
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    Rapid and Accurate Contact Determination between Spline Models using ShellTrees
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Krishnan, S.; Gopi, M.; Lin, M.; Manocha, D.; Pattekar, A.
    In this paper, we present an efficient algorithm for contact determination between spline models. We make use of a new hierarchy, called ShellTree, that comprises of spherical shells and oriented bounding boxes. Each spherical shell corresponds to a portion of the volume between two concentric spheres. Given large spline models, our algorithm decomposes each surface into Bezier patches as part of pre-processing. At runtime it dynamically computes a tight fitting axis-aligned bounding box across each Bezier patch and efficiently checks all such boxes for overlap. Using off-line and on-line techniques for tree construction, our algorithm computes ShellTrees for Bezier patches and performs fast overlap tests between them to detect collisions. The overall approach can trade off runtime performance for reduced memory requirements. We have implemented the algorithm and tested it on large models, each composed of hundred of patches. Its performance varies with the configurations of the objects. For many complex models composed of hundreds of patches, it can accurately compute the contacts in a few milliseconds.
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    Subdivision Schemes for Thin Plate Splines
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Weimer, Henrik; Warren, Joe
    Thin plate splines are a well known entity of geometric design. They are defined as the minimizer of a variational problem whose differential operators approximate a simple notion of bending energy. Therefore, thin plate splines approximate surfaces with minimal bending energy and they are widely considered as the standard "fair" surface model. Such surfaces are desired for many modeling and design applications.Traditionally, the way to construct such surfaces is to solve the associated variational problem using finite elements or by using analytic solutions based on radial basis functions. This paper presents a novel approach for defining and computing thin plate splines using subdivision methods. We present two methods for the construction of thin plate splines based on subdivision: A globally supported subdivision scheme which exactly minimizes the energy functional as well as a family of strictly local subdivision schemes which only utilize a small, finite number of distinct subdivision rules and approximately solve the variational problem. A tradeoff between the accuracy of the approximation and the locality of the subdivision scheme is used to pick a particular member of this family of subdivision schemes.Later, we show applications of these approximating subdivision schemes to scattered data interpolation and the design of fair surfaces. In particular we suggest an efficient methodology for finding control points for the local subdivision scheme that will lead to an interpolating limit surface and demonstrate how the schemes can be used for the effective and efficient design of fair surfaces.
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    Real-time Biomechanically-based Muscle Volume Deformation using FEM
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Zhu, Qing-hong; Chen, Yan; Kaufman, Arie
    This paper presents a voxel-based biomechanical model for muscle deformation using finite element method (FEM) and volume graphics. Hierarchical voxel meshes are reconstructed from filtered segmented muscle images followed by FEM simulation and volume rendering. Physiological muscle force is considered and linear elastic muscle models for both static and dynamic cases are simulated by FEM. Voxel-based wireframe, polygon surface rendering, and volume rendering techniques are applied to show real-time muscle deformation processes as well as realistic animations.
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    Emotion Editing using Finite Elements
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Koch, Rolf M.; Gross, Markus H.; Bosshard, Albert A.
    This paper describes the prototype of a facial expression editor. In contrast to existing systems the presented editor takes advantage of both medical data for the simulation and the consideration of facial anatomy during the definition of muscle groups. The Cl-continuous geometry and the high degree of abstraction for the expression editing sets this system apart from others. Using finite elements we achieve a better precision in comparison to particle systems. Furthermore, a precomputing of facial action units enables us to compose facial expressions by a superposition of facial action geometries in real-time. The presented model is based on a generic facial model using a thin plate and membrane approach for the surface and elastic springs for facial tissue modeling. It has been used successfully for performing facial surgery simulation. We illustrate features of our system with examples from the Visible Human Dataset.T
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    A New Approach for Direct Manipulation of Free-Form Curve
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Zheng, J.M.; Chan, K.W.; Gibson, I.
    There is an increasing demand for more intuitive methods for creating and modifying free-form curves and surfaces in CAD modeling systems. The methods should be based not only on the change of the mathematical parameters, such as control points, knots, and weights, but also on the userâ s specified constraints and shapes. This paper presents a new approach for directly manipulating the shape of a free-form curve, leading to a better control of the curve deformation and a more intuitive CAD modeling interface. The userâ s intended deformation of a curve is automatically converted into the modification of the corresponding NURBS control points and knot sequence of the curve. The algorithm for this approach includes curve elevation, knot refinement, control point repositioning, and knot removal. Several examples shown in this paper demonstrate that the proposed method can be used to deform a NURBS curve into the desired shape. Currently, the algorithm concentrates on the purely geometric consideration. Further work will include the effect of material properties.
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    Mass-Spring Simulation using Adaptive Non-Active Points
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Howlett, P.; Hewitt, W.T.
    This paper introduces an adaptive component to a mass-spring system as used in the modelling of cloth for computer animation. The new method introduces non-active points to the model which can adapt the shape of the cloth at inaccuracies. This improves on conventional uniform mass-spring systems by producing more visually pleasing results when simulating the drape of cloth over irregular objects. The computational cost of simulation is decreased by reducing the complexity of collision handling and enabling the use of coarser mass-spring networks.
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    An Enhanced Spring Model for Information Visualization
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Theisel, Holger; Kreuseler, Matthias
    In this paper we present a new technique for visualizing multidimensional information. We describe objects of a higher dimensional information space as small closed free-form-surfaces in the visualization. The location, size and shape of these surfaces describe the original objects in information space uniquely. The underlying enhanced spring model is introduced. The technique is applied to two test data sets.
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    The Convergence of Graphics and Imaging
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Foley, James D.
    Over twenty years ago a SIGGRAPH panel session addressed the convergence of computer graphics and image processing. At that time the emphasis was on low-level operations such as filtering to avoid anti-aliasing, and related psycho-physics issues. More recently, Graphics and Imaging are converging at a higher level as we move toward blending the synthetic world of computer-generated images with the real world of computer-captured images. In this talk we describe several research directions that relate to this convergence, and illustrate with specific examples of work at MERL - A Mitsubishi Electric Research Laboratory. These research directions are: Analyzing images of the human face to determine identity and orientation and ultimately to reconstruct the shape of the face. Reconstruction of static and dynamic 3D geometries from 2D images separated in time or space: here the objective is to take multiple images of a real-world scene and recreate the 3D geometry of the scene. If objects in the scene are moving, then the objective is extracting the dynamic geometry. Once the geometry has been reconstructed, editing and relighting of the scene becomes possible. Display of 3D scalar fields (also known as volume graphics) concerns 3D as opposed to 2D images, such as CT and MRI scans. These scans can be thought of as 3D images in that they are point samples of a 3D scalar field, just as a computer-captured image is a point sample of a 2D sample field. The objective of volume graphics is to create and display the 3D geometries that underly 3D images. An inexpensive yet real-time (30 fps for a 256 x 256 x 256 image) implementation of Pfister and Kaufmanâ s Cube-4 rendering architecture will be described.
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    The Art of Knitted Fabrics, Realistic & Physically Based Modelling Of Knitted Patterns
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Meißner, M.; Eberhardt, B.
    In this paper we will present a system to use three dimensional computer graphics in garment design. This system is capable to visualize the "real", i.e. the physically correct, appearance of a knitted fabric. A fast visualization of a physically correct micro-structure garment is of crucial importance in textile industry, since it enables fast and less expensive product development. This system may be either used in the design of new products or teaching the art of knitted fabrics.We use in our system directly the produced machine-code of the design system for knitting machines. A physical model, a particle system, is used to calculate the dynamics of the micro-structure of the knitted garment.
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    Anno 2010 - Remembering Our Future: Challenges and Frontiers of Human-Media Technology as the Kernel for Human-Centered Computing
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Encarnacao, Jose
    Based on a forecast by Battelle, Human-Media Technology is one of "technologyâ s top 10 challenges and opportunities" for the year 2010. The subject hereby is: "Humans live, science finds out how technology conforms". The goal is to develop environments that allow users to cooperate in the most efficient and natural way. Human-centered systems will have to incorporate people as an explicit design component. This lecture will address the main goals in developing such systems based on their general characteristics and the corresponding enabling technologies: Visualization (seeing the unseen), Virtual and Augmented Reality (environment must be immersive), and also Multimedia (to introduce the combination of visual, auditory and voice data). Examples from applications and case studies will support the clarification of ideas and goals. Several videos will be used to show the impact.So far, the human-centered interfaces to accommodate human perception and human response capabilities and limitations will have been presented and discussed. These interfaces allow to integrate the desired amount of immersion and cooperation (CSCW). Based on this, some "hands-on" life demos will be shown to discuss the state of the art of these technologies, like Virtual Tables (responsive workbenches), special I/O technologies, etc. Some of these demos will be stand-alone demos; others will show the potential of telecommunication for collaboration by connecting the floor with other locations to demonstrate CSCW-based visual tele-applications.
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    Colour Illustrations
    (Blackwell Publishers Ltd and the Eurographics Association, 1998)
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    Fast Feature-Based Metamorphosis and Operator Design
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Lee, Tong-Yee; Lin, Young-Ching; Sun, Y.N.; Lin, Leeween
    Metamorphosis is a powerful visual technique, for producing interesting transition between two images or volume data. Image or volume metamorphosis using simple features provides flexible and easy control of visual effect. The feature-based image warping proposed by Beier and Neely is a brute-force approach. In this paper, first, we propose optimization methods to reduce their warping time without noticeable loss of image quality. Second, we extend our methods to 3D volume data and propose several interesting warping operators allowing global and local metamorphosis of volume data.
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    Animation of Biological Organ Growth Based on L-systems
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Durikovic, Roman; Kaneda, Kazufumi; Yamashita, Hideo
    In contrast with the growth of plants and trees, human organs can undergo significant changes in shape through a variety of global transformations during the growth period, such as bending or twisting. In our approach, the topology of a human organ is represented by a skeleton in the form of a tree or cycled graph. The length of skeleton growth can be simulated by an algebraic L-system that also produces discrete events. The paper shows how to include global transformations into the formalism of L-systems to obtain a continuous process. The shape of the organ is approximated by a number of ellipsoidal clusters centred at points on the skeleton. The proposed growth model of the organ continually responds to the positional changes of surrounding organs, thereby changing the organ shape locally. In our study, the stomach of a human embryo is used for the demonstration of organ development, and the methodology employed is also applicable to the animation of animal organs and their development.
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    Interactive 3D Morphing
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Bao, Hujun; Peng, Qunsheng
    A new 3D morphing algorithm for polyhedral objects with the same genus is presented in the paper. Our main contribution is an efficient and general algorithm for setting up the vertex correspondence between the polyhedra. The proposed algorithm first interactively partitions the two original polyhedra into the same number of polygonal patches, the patch correspondence is also established during partitioning. Each pair of corresponding patches is then parametrized and resampled by using the harmonic maps. A feature polyhedron is finally constructed for each original polyhedron, and the vertex correspondence between each original polyhedron and its feature polyhedron is automatically established following a cluster scheme. The shape transition between the original polyhedral models is accomplished by composing three successive transformations using their feature polyhedra as the bridges. Experimental results demonstrate that our algorithm is very robust, and can deal with very general cases (non-zero genus polyhedral cases).
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    A Framework for Synchronized Editing of Multiple Curve Representations
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Grimm, Cindy; Ayers, Matthew
    Editing curves and surfaces is difficult in part because their mathematical representations rarely correspond to most peopleâ s idea of a curve or surface. The implementation (and hence, behavior) of most manipulation tools is intertwined with a particular curve or surface representation; this can make reimplementing the tool with a different representation problematic. A system using a single representation must therefore either limit the types of tools available or convert existing tools to work on the systemâ s representation.In this paper we present a framework for editing curves or surfaces which supports multiple representations and ensures that they stay synchronized. As a proof of concept, we have created a curve editor which contains several tools each of which manipulate one of three different curve representations: polylines, NURBs, and multi-resolution B-splines.