Issue 3

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/68
EG 1995 Conference Proceedings

BibTeX (Issue 3)
                
@article{
10.1111:j.1467-8659.1995.cgf143-0003.x,

journal = {Computer Graphics Forum},
title = {{
Distributed Augmented Reality for Collaborative Design Applications}},

author = {
Ahlers, Klaus H.
 and 
Kramer, Andre
 and 
Breen, David E.
 and 
Chevalier, Pierre-Yves
 and 
Crampton, Chris
 and 
Rose, Eric
 and 
Tuceryan, Mihran
 and 
Whitaker, Ross T.
 and 
Greer, Douglas
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0003.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0111.x,

journal = {Computer Graphics Forum},
title = {{
Three Architectures for Volume Rendering}},

author = {
Hesser, Jurgen
 and 
Manner, Reinhard
 and 
Knittel, Gunter
 and 
Strasser, Wolfgang
 and 
Pfister, Hanspeter
 and 
Kaufman, Arie
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0111.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0123.x,

journal = {Computer Graphics Forum},
title = {{
An Incremental Alignment Algorithm for Parallel Volume Rendering}},

author = {
Or, Daniel Cohen
 and 
Fleishman, Shachar
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0123.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0135.x,

journal = {Computer Graphics Forum},
title = {{
A Multimedia Constraint System1}},

author = {
van Hintum, J.E.A.
 and 
Reynolds, G.J.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0135.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0159.x,

journal = {Computer Graphics Forum},
title = {{
Thoughtful Drawings: A Computational Model of the Cognitive Nature of Children s Drawing}},

author = {
Burton, Ed
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0159.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0149.x,

journal = {Computer Graphics Forum},
title = {{
The MADE Help System}},

author = {
Haindl, Michal
 and 
de Ruiter, Behr
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0149.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0181.x,

journal = {Computer Graphics Forum},
title = {{
Algorithms for Extracting Correct Critical Points and Constructing Topological Graphs from Discrete Geographical Elevation Data}},

author = {
Takahashi, Shigeo
 and 
Ikeda, Tetsuya
 and 
Shinagawa, Yoshihisa
 and 
Kunii, Tosiyasu L.
 and 
Ueda, Minoru
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0181.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0171.x,

journal = {Computer Graphics Forum},
title = {{
Visibility and Dead-Zones in Digital Terrain Maps}},

author = {
Or, Daniel Cohen
 and 
Shaked, Amit
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0171.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0217.x,

journal = {Computer Graphics Forum},
title = {{
Shading with Curve Light Sources1}},

author = {
Bao, Hujun
 and 
Ying, Jianguo
 and 
Peng, Qunsheng
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0217.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0015.x,

journal = {Computer Graphics Forum},
title = {{
Object Calibration for Augmented Reality}},

author = {
Whitaker, Ross T.
 and 
Crampton, Chris
 and 
Breen, David E.
 and 
Tuceryan, Mihran
 and 
Rose, Eric
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0015.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0205.x,

journal = {Computer Graphics Forum},
title = {{
Fast Shadowing Algorithm for Linear Light Sources}},

author = {
Tanaka, Toshimitsu
 and 
Takahashi, Tokiichiro
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0205.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0193.x,

journal = {Computer Graphics Forum},
title = {{
Morphological Operations for Color-Coded Images}},

author = {
Busch, Christoph and Eberle, Michael
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0193.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0241.x,

journal = {Computer Graphics Forum},
title = {{
Sketching 3D Animations}},

author = {
Balaguer, Jean-Francis
 and 
Gobbetti, Enrico
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0241.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0229.x,

journal = {Computer Graphics Forum},
title = {{
A Quick Rendering Method Using Basis Functions for Interactive Lighting Design}},

author = {
Dobashi, Yoshinori
 and 
Kaneda, Kazufumi
 and 
Nakatani, Hideki
 and 
Yamashita, Hideo
 and 
Nishita, Tomoyuki
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0229.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0259.x,

journal = {Computer Graphics Forum},
title = {{
An Adaptive Spatial Subdivision of the Object Space for Fast Collision Detection of Animated Rigid Bodies}},

author = {
Bandi, Srikanth
 and 
Thalmann, Daniel
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0259.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0271.x,

journal = {Computer Graphics Forum},
title = {{
A Direct Manipulation Interface for 3D Computer Animation}},

author = {
Snibbe, Scott Sona
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0271.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0285.x,

journal = {Computer Graphics Forum},
title = {{
Multiresolution B-spline Radiosity}},

author = {
Yu, Yizhou
 and 
Peng, Qunsheng
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0285.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0325.x,

journal = {Computer Graphics Forum},
title = {{
Synthetic Vision and Audition for Digital Actors}},

author = {
NOSER, Hansrudi
 and 
THALMANN, Daniel
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0325.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0299.x,

journal = {Computer Graphics Forum},
title = {{
A new radiosity approach for regular objects: application to ruled surfaces}},

author = {
ARQUES, Didier
 and 
MICHELIN, Sylvain
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0299.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0311.x,

journal = {Computer Graphics Forum},
title = {{
Using Procedural RenderMan Shaders for Global Illurnination}},

author = {
Slusallek, Philipp
 and 
Pflaum, Thomas
 and 
Seidel, Hans-Peter
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0311.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0361.x,

journal = {Computer Graphics Forum},
title = {{
Realizing 3D Visual Programming Environments within a Virtual Environment}},

author = {
Van Reeth, F.
 and 
Coninx, K.
 and 
De Backer, S.
 and 
Flerackers, E.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0361.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0337.x,

journal = {Computer Graphics Forum},
title = {{
The HUMANOID Environment for Interactive Animation of Multiple Deformable Human Characters}},

author = {
Boulic, R.
 and 
Capin, T.
 and 
Huang, Z.
 and 
Kalra, P.
 and 
Lintermann, B.
 and 
Magnenat-Thalmann, N.
 and 
Moccozet, L. and Molet, T. and Pandzic, I. and Saar, K. and Schmitt, A. and Shen, J. and Thalmann, D.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0337.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0349.x,

journal = {Computer Graphics Forum},
title = {{
VR-VIBE: A Virtual Environment for Co-operative Information Retrieval}},

author = {
Benford, Steve
 and 
Snowdon, Dave
 and 
Greenhalgh, Chris
 and 
Ingram, Rob
 and 
Knox, Ian
 and 
Brown, Chris
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0349.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0029.x,

journal = {Computer Graphics Forum},
title = {{
Two-step Prediction and Image Deflection for Exact Head Tracking in Virtual Environments}},

author = {
Mazuryk, Tomasz
 and 
Gervautz, Michael
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0029.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0371.x,

journal = {Computer Graphics Forum},
title = {{
Filtering, Clustering and Hierarchy Construction: a New Solution for Ray-Tracing Complex Scenes}},

author = {
Cazals, Frederic
 and 
Drettakis, George
 and 
Puech, Claude
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0371.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0407.x,

journal = {Computer Graphics Forum},
title = {{
Synthesizing Feather Textures in Galliformes}},

author = {
Dai, Wen-Kai
 and 
Shih, Zen-Chung
 and 
Chang, Ruei-Chuan
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0407.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0383.x,

journal = {Computer Graphics Forum},
title = {{
Discrete Ray-Tracing of Huge Voxel Spaces}},

author = {
Stolte, Nilo
 and 
Caubet, Rene
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0383.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0397.x,

journal = {Computer Graphics Forum},
title = {{
Generating a Texture Map from Object-Surface Texture Data}},

author = {
Maruya, Makoto
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0397.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0469.x,

journal = {Computer Graphics Forum},
title = {{
Fair Surface Reconstruction Using Quadratic Functionals}},

author = {
Kolb, Andreas
 and 
Pottmann, Helmut
 and 
Seidel, Hans-Peter
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0469.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0445.x,

journal = {Computer Graphics Forum},
title = {{
A Graph-Based Approach to Surface Reconstruction}},

author = {
Mencl, Robert
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0445.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0457.x,

journal = {Computer Graphics Forum},
title = {{
Automatic Reconstruction of Unstructured 3D Data: Combining a Medial Axis and Implicit Surfaces}},

author = {
Bittar, Eric
 and 
Tsingos, Nicolas
 and 
Gascuel, Marie-Paule
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0457.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0431.x,

journal = {Computer Graphics Forum},
title = {{
Fast Wavelet Based Volume Rendering by Accumulation of Transparent Texture Maps}},

author = {
Lippert, L.
 and 
Gross, M. H.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0431.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0421.x,

journal = {Computer Graphics Forum},
title = {{
Rendering of Surface and Volume Details in Volume Data*}},

author = {
CAI, Wenli
 and 
CHEN, Tianzhou
 and 
SHI, Jiaoying
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0421.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0043.x,

journal = {Computer Graphics Forum},
title = {{
Syntax Channelling and Other Issues affecting Innovation in the Graphical User Interface}},

author = {
King, Mike
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0043.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0067.x,

journal = {Computer Graphics Forum},
title = {{
A Real-time Continuous Alphabetic Sign Language to Speech Conversion VR System}},

author = {
Liang, Rung-Huei
 and 
Ouhyoung, Ming
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0067.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0089.x,

journal = {Computer Graphics Forum},
title = {{
Spherical Triangular B-splines with Application to Data Fitting}},

author = {
Pfeifle, Ron
 and 
Seidel, Hans-Peter
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0089.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0077.x,

journal = {Computer Graphics Forum},
title = {{
A rational model of the surface swept by a curve*}},

author = {
Johnstone, John K.
 and 
Williams, James P.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0077.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0097.x,

journal = {Computer Graphics Forum},
title = {{
Modeling 3D Curves of Minimal Energy}},

author = {
Veltkamp, Remco C.
 and 
Wesselink, Wieger
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0097.x}

}
                
@article{
10.1111:j.1467-8659.1995.cgf143-0055.x,

journal = {Computer Graphics Forum},
title = {{
Reasoning About Gestural Interaction}},

author = {
Duke, D.J.
},
year = {
1995},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.1995.cgf143-0055.x}

}

Browse

Recent Submissions

Now showing 1 - 39 of 39
  • Thumbnail Image
    Item
    Distributed Augmented Reality for Collaborative Design Applications
    (Blackwell Science Ltd and the Eurographics Association, 1995) Ahlers, Klaus H.; Kramer, Andre; Breen, David E.; Chevalier, Pierre-Yves; Crampton, Chris; Rose, Eric; Tuceryan, Mihran; Whitaker, Ross T.; Greer, Douglas
    This paper presents a system for constructing collaborative design applications based on distributed augmented reality. Augmented reality interfaces are a natural method for presenting computer-based design by merging graphics with a view of the real world. Distribution enables users at remote sites to collaborate on design tasks. The users interactively control their local view, try out design options, and communicate design proposals. They share virtual graphical objects that substitute for real objects which are not yet physically created or are not yet placed into the real design environment.We describe the underlying augmented reality system and in particular how it has been extended in order to support multi-user collaboration. The construction of distributed augmented reality applications is made easier by a separation of interface, interaction and distribution issues. An interior design application is used as an example to demonstrate the advantages of our approach.
  • Thumbnail Image
    Item
    Three Architectures for Volume Rendering
    (Blackwell Science Ltd and the Eurographics Association, 1995) Hesser, Jurgen; Manner, Reinhard; Knittel, Gunter; Strasser, Wolfgang; Pfister, Hanspeter; Kaufman, Arie
    Volume rendering is a key technique in scientific visualization that lends itself to significant exploitable parallelism. The high computational demands of real-time volume rendering and continued technological advances in the area of VLSl give impetus to the development of special-purpose volume rendering architectures. This paper presents and characterizes three recently developed volume rendering engines which are based on the ray-casting method. A taxonomy of the algorithmic variants of ray-casting and details of each ray-casting architecture are discussed. The paper then compares the machinefeatures and provides an outlook onfuture developments in the area of volume rendering hardware.
  • Thumbnail Image
    Item
    An Incremental Alignment Algorithm for Parallel Volume Rendering
    (Blackwell Science Ltd and the Eurographics Association, 1995) Or, Daniel Cohen; Fleishman, Shachar
    This paper introduces a data distribution scheme and an alignment algorithm for parallel volume rendering. The algorithm performs a single wrap-around shear transformation which requires only a regular inter-processor communication pattern. The alignment can be implemented incrementally consisting of short distance shifts, thus significantly reducing the communication overhead. The alignment process is a non-destructive transformation, consisting of a single non-scaling shear operation. This is a unique feature which provides the basis for the incremental algorithm.
  • Thumbnail Image
    Item
    A Multimedia Constraint System1
    (Blackwell Science Ltd and the Eurographics Association, 1995) van Hintum, J.E.A.; Reynolds, G.J.
    The MADE constraint system provides excellent opportunities to introduce constraints in a multimedia application. Multimedia applications are not only a good place to experiment with constraint systems- constraints in a multimedia environment are almost indispensable. Due to the overwhelming amount of data and the number of relations between several parts of this data, multimedia applications almost demand the support of a constraint management system.The MADE constraint system combines the object oriented programming paradigm, inherited from the mC++ language, the declarative constraint programming paradigm and the special requirements imposed upon the constraint system by the multimedia environment. Among other things, the MADE constraint system provides parallel satisfaction techniques- several constraints may be solved simultaneously and this satisfaction process is performed in parallel with the application. This not only reduces the time needed to solve the constraints, it also allows the multimedia application to proceed with its presentation while (beneath the surface) the constraints are maintained. This not only holds for the parts of the presentation that are not constrained at all, but also for those parts that are. Furthermore, the constraint system is transparent to the multimedia application- no special coding or preparation of the objects in the application is necessary. Constraints can be added later to the application without much work. Besides that, it is also possible to add and remove constraints at runtime- objects may be constrained for only a period of the time the application is running.
  • Thumbnail Image
    Item
    Thoughtful Drawings: A Computational Model of the Cognitive Nature of Children s Drawing
    (Blackwell Science Ltd and the Eurographics Association, 1995) Burton, Ed
    An interpretation of children s drawing is presented that is based on active perception of the world and the construction of an equivalent self contained two-dimensional world. This model is implemented in a computer program called Rose (Representation Of Spatial Experience). Inspired by the drawings of young children, Rose simulates the perception of the general form and structure of three-dimensional computer models and constructs equivalent childlike two-dimensional representations from them. Rose serves to illustrate the plausibility of the constructive process as a model for real children s drawing and in addition serves as an alternative approach to traditional computer graphic rendering.
  • Thumbnail Image
    Item
    The MADE Help System
    (Blackwell Science Ltd and the Eurographics Association, 1995) Haindl, Michal; de Ruiter, Behr
    MADE is the acronym for the ESPRIT project 6307, whose aim is to develop an object oriented multimedia application development environment. As part of this project the MADE help system is designed to be a distributed hypermedia system with additional support for run-time object monitoring and contextual help.
  • Thumbnail Image
    Item
    Algorithms for Extracting Correct Critical Points and Constructing Topological Graphs from Discrete Geographical Elevation Data
    (Blackwell Science Ltd and the Eurographics Association, 1995) Takahashi, Shigeo; Ikeda, Tetsuya; Shinagawa, Yoshihisa; Kunii, Tosiyasu L.; Ueda, Minoru
    Researchers in the fields of computer graphics and geographical information systems (GISs) have extensively studied the methods of extracting terrain features such as peaks, pits, passes, ridges, and ravines from discrete elevation data. The existing techniques, however, do not guarantee the topological integrity of the extracted features because of their heuristic operations, which results in spurious features. Furthermore, there have been no algorithms for constructing topological graphs such as the surface network and the Reeb graph from the extracted peaks, pits, and passes. This paper presents new algorithms for extracting features and constructing the topological graphs using the features. Our algorithms enable us to extract correct terrain features; i.e., our method extracts the critical points that satisfy the Euler formula, which represents the topological invariant of smooth surfaces. This paper also provides an algorithm that converts the surface network to the Reeb graph for representing contour changes with respect to the height. The discrete elevation data used in this paper is a set of sample points on a terrain surface. Examples are presented to show that the algorithms also appeal to our visual cognition.
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    Visibility and Dead-Zones in Digital Terrain Maps
    (Blackwell Science Ltd and the Eurographics Association, 1995) Or, Daniel Cohen; Shaked, Amit
    The problem of detecting the visible and hidden areas of a topographic surface from a given viewpoint is well known, and has applications in GIS and other fields. The computational geometry literature is rich with solutions based on a polygonal representation of the surface. This work confronts the problem by working directly on the Digital Elevation Map which represents the terrain surface. We present an algorithm that processes discrete lines of sight from the viewpoint to the surface perimeter, and tests the unit-sized terrain elements along the discrete cross-sections defined by these lines. The algorithm is very efficient, performing O(n) testing operations, consisting of a few additions and no more than one multiplication each, where n is the number of the terrain elements in the map.
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    Shading with Curve Light Sources1
    (Blackwell Science Ltd and the Eurographics Association, 1995) Bao, Hujun; Ying, Jianguo; Peng, Qunsheng
    A new shading model for curve light sources is presented. It accounts for both diffuse reflection and specular reflection of the illuminated surface. By regarding a linear light source as a directional quadrilateral light source with very small width, a simple formula is derived first for calculating the diffuse reflection component due to the illumination of the linear segment. The diffuse reflection of the surface by direct illumination of a curve light source is then evaluated by approximating the curve light with a series of linear segments. The specular reflection component due to a curve light source is represented by an integration taking Phong s specular model as the kernel and evaluated by summing the contributions from the linear segments. Finally, an efficient shadow detection algorithm for curve light sources is proposed. The images rendered with the shading model are very photo-realistic.
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    Object Calibration for Augmented Reality
    (Blackwell Science Ltd and the Eurographics Association, 1995) Whitaker, Ross T.; Crampton, Chris; Breen, David E.; Tuceryan, Mihran; Rose, Eric
    Augmented reality involves the use of models and their associated renderings to supplement information in a real scene. In order for this information to be relevant or meaningful, the models must be positioned and displayed in such a way that they align with their corresponding real objects. For practical reasons this alignment cannot be known a priori, and cannot be hard-wired into a system. Instead a simple, reliable alignment or calibration process is performed so that computer models can be accurately registered with their real-life counterparts. We describe the design and implementation of such a process and we show how it can be used to create convincing interactions between real and virtual objects.
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    Fast Shadowing Algorithm for Linear Light Sources
    (Blackwell Science Ltd and the Eurographics Association, 1995) Tanaka, Toshimitsu; Takahashi, Tokiichiro
    This paper presents a fast shadowing algorithm for linear light sources that uses a ray-oriented buffer. Space segmentation by the buffer guarantees that if a point is included in a subspace, all light rays toward the point are also contained in the subspace. Each cell of the buffer stores a list of objects that lie within or intersect the subspace allocated to the cell. Therefore, candidate objects, those that may cast shadows onto a point, are determined by referring to the cell where the point is mapped. In addition, whether each candidate object actually casts shadows or not is tested with the bounding-volume of the shadow space to reduce the number of objects subjected to expensive light clipping. The bounding-volumes are also stored in the buffer. For efficiently generating the ray-oriented buffer, we present the cylindrical scan-conversion algorithm. The algorithm preconverts objects surfaces to trapezia to decrease the light clipping cost, then connects the trapezia to the buffer cells.Due to the above improvements, our algorithm achieves over 10 times faster shadow generation compared to the conventional methods. Experimental results confirm that our method can generate realistic images with soft shadows in a few minutes.
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    Morphological Operations for Color-Coded Images
    (Blackwell Science Ltd and the Eurographics Association, 1995) Busch, Christoph and Eberle, Michael
    The subject of this paper is the semantically based postprocessing of color-coded images such as classification results. We outline why the classical definition of mathematical morphology suffers if it is used for processing of coded image data. Therefore we provide an extension for morphological operations such as dilation, erosion, opening, and closing. With a new understanding of morphology we introduce bridging and tunneling as further combinations of dilation and erosion. The extensions are applied to medical image data, where the semantic rules stem from basic anatomical knowledge.
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    Sketching 3D Animations
    (Blackwell Science Ltd and the Eurographics Association, 1995) Balaguer, Jean-Francis; Gobbetti, Enrico
    We are interested in providing animators with a general-purpose tool allowing them to create animations using straight-ahead actions as well as pose-to-pose techniques. Our approach seeks to bring the expressiveness of real-time motion capture systems into a general-purpose multi-track system running on a graphics workstation. We emphasize the use of high-bandwidth interaction with 3D objects together with specific data reduction techniques for the automatic construction of editable representations of interactively sketched continuous parameter evolution. In this paper, we concentrate on providing a solution to the problem of applying data reduction techniques in an animation context. The requirements that must be fulfilled by the data reduction algorithm are analyzed. From the Lyche and Morken knot removal strategy, we derive an incremental algorithm that computes a B-spline approximation to the original curve by considering only a small piece of the total curve at any time. This algorithm allows the processing of the user s captured motion in parallel with its specification, and guarantees constant latency time and memory needs for input motions composed of any number of samples. After showing the results obtained by applying our incremental algorithm to 3D animation paths, we describe an integrated environment to visually construct 3D animations, where all interaction is done directly in three dimensions. By recording the effects of user s manipulations and taking into account the temporal aspect of the interaction, straight-ahead animations can be defined. Our algorithm is automatically applied to continuous parameter evolution in order to obtain editable representations. The paper concludes with a presentation offuture work.
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    A Quick Rendering Method Using Basis Functions for Interactive Lighting Design
    (Blackwell Science Ltd and the Eurographics Association, 1995) Dobashi, Yoshinori; Kaneda, Kazufumi; Nakatani, Hideki; Yamashita, Hideo; Nishita, Tomoyuki
    When designing interior lighting effects, it is desirable to compare a variety of lighting designs involving different lighting devices and directions of light. It is, however, time-consuming to generate images with many different lighting parameters, taking interreflection into account, because all luminances must be calculated and recalculated. This makes it difficult to design lighting effects interactively. To address this problem, this paper proposes a method of quickly generating images of a given scene illustrating an interreflective environment illuminated by sources with arbitrary luminous intensity distributions. In the proposed method, the luminous intensity ditribution is expressed with basis functions. The proposed method uses a series of spherical harmonic functions as basis functions, and calculates in advance each intensity on surfaces lit by the light sources whose luminous intensity distribution are the same as the spherical harmonic functions. The proposed method makes it possible to generate images so quickly that we can change the luminous intensity distribution interactively. Combining the proposed method with an interactive walk-through that employs intensity mapping, an interactive system for lighting design is implemented. The usefulness of the proposed method is demonstrated by its application to interactive lighting design, where many images are generated by altering lighting devices and/or direction of light.
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    An Adaptive Spatial Subdivision of the Object Space for Fast Collision Detection of Animated Rigid Bodies
    (Blackwell Science Ltd and the Eurographics Association, 1995) Bandi, Srikanth; Thalmann, Daniel
    Collision detection tests between objects dominate run time simulation of rigid body animation. Traditionally, hierarchical bounding box tests are used to minimize collision detection time. But the bounding boxes do not take shapes of the objects into account which results in a large number of collision detection tests. We propose an adaptive spatial subdivision of the object space based on octree structure to rectify this problem. We also present a technique for efficiently updating this structure periodically during the simulation.
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    A Direct Manipulation Interface for 3D Computer Animation
    (Blackwell Science Ltd and the Eurographics Association, 1995) Snibbe, Scott Sona
    We present a new set of interface techniques for visualizing and editing animation directly in a single three-dimensional scene. Motion is edited using direct-manipulation tools which satisfy high-level goals such as"reach this point at this time" or"go faster at this moment". These tools can be applied over an arbitrary temporal range and maintain arbitrary degrees of spatial and temporal continuity.We separate spatial and temporal control of position by using two curves for each animated object: the motion path which describes the 3D spatial path along which an object travels, and the motion graph, a function describing the distance traveled along this curve over time. Our direct-manipulation tools are implemented using displacement functions, a straightforward and scalable technique for satisfying motion constraints by composition of the displacement function with the motion graph or motion path. This paper will focus on applying displacement functions to positional change. However, the techniques presented are applicable to the animation of orientation, color, or any other attribute that varies over time.
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    Multiresolution B-spline Radiosity
    (Blackwell Science Ltd and the Eurographics Association, 1995) Yu, Yizhou; Peng, Qunsheng
    This paper introduces a kind of new wavelet radiosity method called multiresolution B-spline radiosity, which uses B-splines of different scales to represent radiosity distribution functions. A set of techniques and algorithms, such as function extrapolation, adaptive quadrature, scale adjustment and octree, are proposed to implement it. This method sets up hierarchical structures on surfaces, keeps radiosity distribution continuous at element boundaries, does not need postprocessing, and does not prevent the use of any surface whose parameter domain is rectilinear.
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    Synthetic Vision and Audition for Digital Actors
    (Blackwell Science Ltd and the Eurographics Association, 1995) NOSER, Hansrudi; THALMANN, Daniel
    We present an overview of some principles of synthetic vision and audition for digital autonomous actors in virtual worlds. After a short review of the state-of-the-art we focus on some aspects of synthetic vision and virtual world constraints. Then, we present a simple real time structured sound renderer. This sound renderer is used as audition channel for synthetic and real actors and synchronized sound track generator for video film productions.
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    A new radiosity approach for regular objects: application to ruled surfaces
    (Blackwell Science Ltd and the Eurographics Association, 1995) ARQUES, Didier; MICHELIN, Sylvain
    This paper introduces a new approach in the radiosity method. The main principle applied here, is the improvement of form factor computation by the knowledge of the model properties. More precisely, if surfaces describing a scene are"regular", the values of the form factor and its"derivatives" between any patch B and a patch A intervening in the meshing of a given surface, enable us to evaluate (with a required precision) the form factors values between B and the neighboring patches of A. We will also show that the mathematical relation we have obtained, 1) is especially efficient with ruled surfaces, 2) significantly decreases the computation time, 3) is well-adapted to refinement or subdivision techniques and 4) gives us an interesting variety of surfaces. Calculation times are equivalent to those obtained with a projective method (hemi-cube for example) but with an efficient control of the generated errors.
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    Using Procedural RenderMan Shaders for Global Illurnination
    (Blackwell Science Ltd and the Eurographics Association, 1995) Slusallek, Philipp; Pflaum, Thomas; Seidel, Hans-Peter
    Global illumination techniques like radiosity or Monte-Carlo ray-tracing are becoming standard features of rendering systems. However, there is currently no accepted interface format which supports an appropriate physically-based scene description. In this paper we present extensions to the well-known RenderMan interface, which allow for a physically based scene description and support advanced global illumination techniques. Special emphasis has been laid on the support for procedural descriptions of reflection and emission by RenderMan surface shaders. So far, they could not be used with most global illumination algorithms. The extensions have been implemented in a physically-based rendering system and are illustrated with examples.
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    Realizing 3D Visual Programming Environments within a Virtual Environment
    (Blackwell Science Ltd and the Eurographics Association, 1995) Van Reeth, F.; Coninx, K.; De Backer, S.; Flerackers, E.
    In the visual programming community, many interesting graphical metaphors have been reported upon for representing computer programs graphically. Most of them have a 2D or 2.5D appearance on the screen in order to reflect the inherent multi-dimensionality of the programming constructs being represented. By going into a three-dimensional representation, this reflection can go a stepfurther. With ever increasing3D graphics rendering capabilities on todays computers, it moreover becomes feasible to extend the dimensionality of the program (and data structure) depiction. We follow this approach by realizing 3D graphical programming techniques within CAEL, our interactive Computer Animation Environment Language. The paper elucidates how several concepts, traditionally found within the Virtual Environments area, can be utilized in the realization of three-dimensional Programming Environments.
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    The HUMANOID Environment for Interactive Animation of Multiple Deformable Human Characters
    (Blackwell Science Ltd and the Eurographics Association, 1995) Boulic, R.; Capin, T.; Huang, Z.; Kalra, P.; Lintermann, B.; Magnenat-Thalmann, N.; Moccozet, L. and Molet, T. and Pandzic, I. and Saar, K. and Schmitt, A. and Shen, J. and Thalmann, D.
    We describe the HUMANOID environment dedicated to human modeling and animation for general multimedia, VR, and CAD applications integrating virtual humans. We present the design of the system and the integration of the various features: generic modeling of a large class of entities with the BODY data structure, realistic skin deformation for body and hands, facial animation, collision detection, integrated motion control and parallelization of computation intensive tasks.
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    VR-VIBE: A Virtual Environment for Co-operative Information Retrieval
    (Blackwell Science Ltd and the Eurographics Association, 1995) Benford, Steve; Snowdon, Dave; Greenhalgh, Chris; Ingram, Rob; Knox, Ian; Brown, Chris
    We present a virtual reality application called VR-VIBE which is intended to support the co-operative browsing and filtering of large document stores. VR-VIBE extends a visualisation approach proposed in a previous two dimensional system called VIBE into three dimensions, allowing more information to be visualised at one time and supporting more powerful styles of interaction, The essence of VR-VIBE is that multiple users can explore the results of applying several simultaneous queries to a corpus of documents. By arranging the queries into a spatial framework, the system shows the relative attraction of each document to each query by its spatial position and also shows the absolute relevance of each document to all of the queries. Users may then navigate the space, select individual documents, control the display according to a dynamic relevance threshold and dynamically drag the queries to new positions to see the effect on the document space. Co-operative browsing is supported by directly embodying users and providing them with the ability to interact over live audio connections and to attach brief textual annotations to individual documents. Finally, we conclude with some initial observations gleaned from our experience of constructing VR-VIBE and using it in the laboratory setting.
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    Two-step Prediction and Image Deflection for Exact Head Tracking in Virtual Environments
    (Blackwell Science Ltd and the Eurographics Association, 1995) Mazuryk, Tomasz; Gervautz, Michael
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    Filtering, Clustering and Hierarchy Construction: a New Solution for Ray-Tracing Complex Scenes
    (Blackwell Science Ltd and the Eurographics Association, 1995) Cazals, Frederic; Drettakis, George; Puech, Claude
    Data structures that handle very complex scenes (hundreds of thousands of objects) have in the past either been laboriously built by hand, or have required the determination of unintuitive parameter values by the user. It is often the case that an incorrect choice of these parameters can result in greedy memory requirements or severely degraded performance. As a remedy to this problem we propose a new data structure which is fully automatic since it does not require the user to determine any input parameters. The structure is built by first filtering the input objects by size, subsequently applying a clustering step to objects of the same size and finally building a hierarchy of uniform grids . We then show that this data structure can be efficiently constructed. The implementation of the shows that the new structure is stable since it s memory requirements grow linearly with the size of the scene, and that it presents a satisfactory compromise between memory usage and computational efficiency. A detailed comparison with previous data structures is also presented in the results.
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    Synthesizing Feather Textures in Galliformes
    (Blackwell Science Ltd and the Eurographics Association, 1995) Dai, Wen-Kai; Shih, Zen-Chung; Chang, Ruei-Chuan
    The texture of feather is one of the most fascinating, complicated, and beautiful texture patterns in nature. In this paper, we propose a new and effective texture generation approach that uses the traits of iteration behavior to synthesize the textures of Galliformes feathers realistically. We also propose an interactive feather modeling approach which provides a close connection between the user s intuition and the resulting branching pattern. In texturing the feather structure, we use an object-space mapping technique. Experimental results are presented to show the effectiveness of our method.
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    Discrete Ray-Tracing of Huge Voxel Spaces
    (Blackwell Science Ltd and the Eurographics Association, 1995) Stolte, Nilo; Caubet, Rene
    The quality of images produced by Discrete Ray-Tracing voxel spaces is highly dependent on 3d grid resolution. The huge amount of memory needed to store such grids often discards discrete Ray-Tracing as a practical visualization algorithm. The use of an octree can drastically change this when most of space is empty, as such is the case in most scenes.Although the memory problem can be bypassed using the octree, the performance problem still remains. A known fact is that the performance of discrete traversal is optimal for quite low resolutions. This problem can be easily solved by dividing the task in two steps, working in two low resolutions instead of just one high resolution, thus taking advantage of optimal times in both steps. This is possible thanks to the octree property of representing the same scene in several different resolutions. This article presents a two step Discrete Ray-Tracing method using an octree and shows, by comparing it with the single step version, that a substantial gain in performance is achieved.
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    Generating a Texture Map from Object-Surface Texture Data
    (Blackwell Science Ltd and the Eurographics Association, 1995) Maruya, Makoto
    A number of 3D digitizing methods, including stereopsis, are capable of measuring not only an object s shape but also its surface texture. Measured shape data can be expressed as a polyhedron whose faces are triangular, and object-surface texture data can be represented in the form of color data for each of the vertices of the various triangles. The ability to apply object-surface texture data directly to the creation of computer graphics images has been severely limited by the extreme difficulty of expressing such texture data in the image from which conventional texture mapping proceeds (commonly referred to as a texture map). Proposed here is a method that generates a texture map from object-surface texture data. First, the method reduces the number of triangles in the polyhedron while preserving essentially all the color data that it originally contained. Next, it arranges the triangles in the simplified triangle mesh onto a plane, and generates a texture map from this arrangement. This method preserves the full texture of an object, no matter how complex its shape, an advantage over the conventional cylindrical texture representation approach. Furthermore, since essentially all color data has been retained, the reduction in the number of triangles does not produce any significant reduction in the texture-realism of the object image produced.
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    Fair Surface Reconstruction Using Quadratic Functionals
    (Blackwell Science Ltd and the Eurographics Association, 1995) Kolb, Andreas; Pottmann, Helmut; Seidel, Hans-Peter
    An algorithm for surface reconstruction from a polyhedron with arbitrary topology consisting of triangular faces is presented. The first variant of the algorithm constructs a curve network consisting of cubic Bezier curves meeting with tangent plane continuity at the vertices. This curve network is extended to a smooth surface by replacing each of the networks facets with a split patch consisting of three triangular Bezier patches. The remaining degrees of freedom of the curve network and the split patches are determined by minimizing a quadratic functional. This optimization process works either for the curve network and the split patches separately or in one simultaneous step. The second variant of our algorithm is based on the construction of an optimized curve network with higher continuity. Examples demonstrate the quality of the different methods.
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    A Graph-Based Approach to Surface Reconstruction
    (Blackwell Science Ltd and the Eurographics Association, 1995) Mencl, Robert
    A new approach to the reconstruction of a surface from an unorganized set of points in space is presented. The point set may for example be obtained with a laser scanner or a manual digitizing tool, and is the only source of information about the shape of the acquired object. The basic idea is to calculate the Euclidean minimum spanning tree (EMST) of the given points. The EMST is then augmented to the so-called surface description graph (SDG). Finally the wire frame defined by the SDG are filled with triangles. The advantage of our approach is that also highly non-convex and even disconnected surfaces are reconstructed quite reliably. This is demonstrated for a variety of data sets.
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    Automatic Reconstruction of Unstructured 3D Data: Combining a Medial Axis and Implicit Surfaces
    (Blackwell Science Ltd and the Eurographics Association, 1995) Bittar, Eric; Tsingos, Nicolas; Gascuel, Marie-Paule
    This paper presents a new method that combines a medial axis and implicit surfaces in order to reconstruct a 3D solid from an unstructured set of points scattered on the object s surface. The representation produced is based on iso-surfaces generated by skeletons, and is a particularly compact way of defining a smooth free-form solid. The method is based on the minimisation of an energy representing a"distance" between the set of data points and the iso-surface, resembling previous reserach19. Initialisation, however, is more robust and efficient since there is computation of the medial axis of the set of points. Instead of subdividing existing skeletons in order to refine the object s surface, a new reconstruction algorithm progressively selects skeleton-points from the pre- computed medial axis using an heuristic principle based on a"local energy" criterion. This drastically speeds up the reconstruction process. Moreover, using the medial axis allows reconstruction of objects with complex topology and geometry, like objects that have holes and branches or that are composed of several connected components. This process is fully automatic. The method has been successfully applied to both synthetic and real data.
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    Fast Wavelet Based Volume Rendering by Accumulation of Transparent Texture Maps
    (Blackwell Science Ltd and the Eurographics Association, 1995) Lippert, L.; Gross, M. H.
    In the following paper, a new method for fast and accurate volume intensity and color integration is elaborated, which employs wavelet decompositions and texture mapping. At this point, it comprises and unifies the advantages of recently introduced Fourier domain volume rendering techniques and wavelet based volume rendering. Specifically, the method computes analytic solutions of the ray intensity integral through a single wavelet by slicing its Fourier transform and by backprojecting it into the spatial domain. The resulting slices can be considered as RGB textures where R, G and B account for the decomposed volume color function. Due to the similarity of the basis functions, the computation of the texture map has to be figured out only once for each 3D mother wavelet. Hence, the final volume rendering procedure turns out to be a superposition of self-similar, transparent and colored textures, which is supported by modern hardware accumulation buffers. Linear shading and attenuation can be introduced by modifications of the wavelet s Fourier transform.The main advantages of this method are the provision of accurate solutions and quantification of error bounds, the absence of any expensive prefiltering and the independence of the computational costs from the image resolution. Furthermore, any required discretization, such as the resolution of the basis textures is defined within the computational framework of the wavelet transform. The method is not restricted to a specific type of wavelet unless is provides an analytic Fourier description, such as any B-spline wavelets do.
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    Rendering of Surface and Volume Details in Volume Data*
    (Blackwell Science Ltd and the Eurographics Association, 1995) CAI, Wenli; CHEN, Tianzhou; SHI, Jiaoying
    Aiming at the detail rendering in volume data, a new volume illumination model, called Composed Scattering Model (CSM), is presented. In order to enhance different details in volume data, scattering intensity is decomposed into volume scattering intensity and surface scattering intensity with different weight functions. According to the Gauss probability distribution of gray and gradient of data, we propose an accurate method to detect the materials in a voxel, called composed segmentation. In addition, we discuss the principle of constructing these weight functions based on the operators defined in composed segmentation. CSM can generate images containing more details than most popular volume rendering models. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated as an accurate volume rendering model suited for detail enhancement in volume data sets.
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    Syntax Channelling and Other Issues affecting Innovation in the Graphical User Interface
    (Blackwell Science Ltd and the Eurographics Association, 1995) King, Mike
    Does the modern commercial Graphical User Interface constrain the developer of graphics applications into certain interaction styles? This paper looks at the Microsoft Windows environment as an example, with particular reference to the question of interaction modes, screen real-estate and visual appearance. The concept of syntax channelling is introduced to help analyse the problem of modality, and the question of button-down versus button-up dragging is debated in the context of a range of commercial applications, and possible consequences for upper limb disorder. A Windows application developed by the author involving the implementation of a variety of innovative interfacing techniques is presented.
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    A Real-time Continuous Alphabetic Sign Language to Speech Conversion VR System
    (Blackwell Science Ltd and the Eurographics Association, 1995) Liang, Rung-Huei; Ouhyoung, Ming
    Many ways of communications are used between human and computer, while using gesture is considered to be one of the most natural way in a virtual reality system. Because of its intuitiveness and its capability of helping the hearing impaired or speaking impaired, we develop a gesture recognition system. Considering the world-wide use of ASL (American Sign Language), this system focuses on the recognition of a continuous flow of alphabets in ASL to spell a word followed by the speech synthesis, and adopts a simple and efficient windowed template matching recognition strategy to achieve the goal of a real-time and continuous recognition. In addition to the abduction and the flex information in a gesture, we introduce a concept of contact-point into our system to solve the intrinsic ambiguities of some gestures in ASL. Five tact switches, served as contact-points and sensed by an analogue to digital board, are sewn on a glove cover to enhance the functions of a traditional data glove.
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    Spherical Triangular B-splines with Application to Data Fitting
    (Blackwell Science Ltd and the Eurographics Association, 1995) Pfeifle, Ron; Seidel, Hans-Peter
    Triangular B-splines surfaces are a tool for representing arbitrary piecewise polynomial surfaces over planar triangulations, while automatically maintaining continuity properties across patch boundaries. Recently, Alfeld et al. [1] introduced the concept of spherical barycentric coordinates which allowed them to formulate Bernstein-Bezier polynomials over the sphere.In this paper we use the concept of spherical barycentric coordinates to develop a similar formulation for triangular B-splines, which we call spherical triangular B-splines. These splines defined over spherical triangulations share the same continuity properties and similar evaluation algorithms with their planar counterparts, but possess none of the annoying degeneracies found when trying to represent closed surfaces using planar parametric surfaces. We also present an example showing the use of these splines for approximating spherical scattered data.
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    A rational model of the surface swept by a curve*
    (Blackwell Science Ltd and the Eurographics Association, 1995) Johnstone, John K.; Williams, James P.
    This paper shows how to construct a rational Bezier model of a swept surface that interpolates N frames (i.e., N position/orientation pairs) of a fixed rational space curve c(s) and maintains the shape of the curve at all intermediate points of the sweep. Thus, the surface models an exact sweep of the curve, consistent with the given data. The primary novelty of the method is that this exact modeling of the sweep is achieved without sacrificing a rational representation for the surface. Through a simple extension, we also allow the sweeping curve to change its size through the sweep. The position, orientation, and size of the sweeping curve can change with arbitrary continuity (we use C2 continuity in this paper). Our interpolation between frames has the classical properties of Bezier interpolation, such as the convex hull property and linear precision.This swept surface is a useful primitive for geometric design. It encompasses the surface of revolution and extruded surface, but extends them to arbitrary sweeps. It is a useful modeling primitive for robotics and CAD/CAM, using frames generated automatically by a moving robot or tool.
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    Modeling 3D Curves of Minimal Energy
    (Blackwell Science Ltd and the Eurographics Association, 1995) Veltkamp, Remco C.; Wesselink, Wieger
    Modeling a curve through minimizing its energy yields an overall smooth curve. A common way to model shape features is to perform the minimization subject to a number of interpolation constraints. This way of modeling is attractive because the designer is not bothered with the precise representation of the curve (e.g. control points). However, local shape specification by means of interpolation constraints is very limited. On the other hand, local deformation by repositioning control points is powerful but very laborious, and destroys the minimal energy property. In this paper, deform operators are introduced for 3D curve modeling that have built-in energy terms that have an intuitive effect. These operators allow local shape modification and do justice to the energy minimization way of modeling.
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    Reasoning About Gestural Interaction
    (Blackwell Science Ltd and the Eurographics Association, 1995) Duke, D.J.
    Many of the reported developments in the design of virtual spaces or visualisation systems are based on improvements in technology, either physical devices or algorithms for achieving realistic renderings within real-time constraints. While this experimental approach produces a wealth of empirical results, it operates largely without a sound underlying theory that can be used to design systems that will effectively support users in real-world domains. One of the main problems is that these sophisticated technologies rely on, but rarely assess, the cognitive abilities of the user. This paper introduces a new approach to modelling human-system interaction. A syndetic model combines a formal expression of system behaviour with an approximate representation of cognitive resources to allow reasoning about the flow and utilisation of information within the combined system. The power of the approach to provide insight into novel interaction techniques is illustrated by developing a syndetic model of a gesture-driven user interface.