Issue 3

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/50
EG 1992 Conference Proceedings

BibTeX (Issue 3)
                
@article{
10.1111:1467-8659.1130001,

journal = {Computer Graphics Forum},
title = {{
An Open Model for Hypermedia and Its Application to Geographical Information Systems}},

author = {
Hall, W.
 and 
Simmons, D.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130001}

}
                
@article{
10.1111:1467-8659.1130119,

journal = {Computer Graphics Forum},
title = {{
Stochastic Motion-Motion Under the Influence of Wind}},

author = {
Shinya, Mikio
 and 
Fournier, Alain
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130119}

}
                
@article{
10.1111:1467-8659.1130107,

journal = {Computer Graphics Forum},
title = {{
A Functional Approach to the Visual Simulation of Gaseous Turbulence}},

author = {
Sakas, Georgios
 and 
Westermann, Rudiger
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130107}

}
                
@article{
10.1111:1467-8659.1130153,

journal = {Computer Graphics Forum},
title = {{
Template-Based Volume Viewing}},

author = {
Yagel, Roni
 and 
Kaufman, Arie
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130153}

}
                
@article{
10.1111:1467-8659.1130129,

journal = {Computer Graphics Forum},
title = {{
A Unified Approach for Physical and Geometric Modeling for Graphics and Animation}},

author = {
Essa, Irfan A.
 and 
Sclaroff, Stan
 and 
Pentland, Alex
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130129}

}
                
@article{
10.1111:1467-8659.1130139,

journal = {Computer Graphics Forum},
title = {{
The Visualization Input Pipeline - Enabling Semantic Interaction in Scientific Visualization}},

author = {
Felger, W.
 and 
Schroder, F.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130139}

}
                
@article{
10.1111:1467-8659.1130181,

journal = {Computer Graphics Forum},
title = {{
Radiosity in Flatland}},

author = {
Heckhert, Paul S.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130181}

}
                
@article{
10.1111:1467-8659.1130205,

journal = {Computer Graphics Forum},
title = {{
An adaptive Discretization Method For Radiosity}},

author = {
Languenou, Eric
 and 
Bouatouch, Kadi
 and 
Tellier, Pierre
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130205}

}
                
@article{
10.1111:1467-8659.1130169,

journal = {Computer Graphics Forum},
title = {{
Fast Generation and Surface Structuring Methods for Terrain and Other Natural Phenomena}},

author = {
Koh, Eng-Kiat
 and 
Hearn, D. D.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130169}

}
                
@article{
10.1111:1467-8659.1130193,

journal = {Computer Graphics Forum},
title = {{
The Parametric Differential Method: An Alternative to the Calculation of Form Factors}},

author = {
Baranoski, Gladimir V. Guimaraes
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130193}

}
                
@article{
10.1111:1467-8659.1130227,

journal = {Computer Graphics Forum},
title = {{
Affine Texture Mapping and Antialiasing Using Integer Arithmetic}},

author = {
Nehlig, P.
 and 
Ghazanfarpour, D.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130227}

}
                
@article{
10.1111:1467-8659.1130217,

journal = {Computer Graphics Forum},
title = {{
Modelling the Texture of Paint}},

author = {
Cockshott, Tunde
 and 
Patterson, John
 and 
England, David
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130217}

}
                
@article{
10.1111:1467-8659.1130009,

journal = {Computer Graphics Forum},
title = {{
Visual Composition and Multimedia}},

author = {
de Mey, Vicki
 and 
Breiteneder, Christian
 and 
Dami, Laurent
 and 
Gibbs, Simon and Tsichritzis, Dennis
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130009}

}
                
@article{
10.1111:1467-8659.1130237,

journal = {Computer Graphics Forum},
title = {{
The Input Model of Standard Graphics Systems Revisited by Formal Specification}},

author = {
Faconti, Giorgio P.
 and 
Zani, Nicola
 and 
Paterno , Fabio
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130237}

}
                
@article{
10.1111:1467-8659.1130253,

journal = {Computer Graphics Forum},
title = {{
A line clipping algorithm and its analysis}},

author = {
Krammer, Gergely
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130253}

}
                
@article{
10.1111:1467-8659.1130267,

journal = {Computer Graphics Forum},
title = {{
A Run-Length Slice Line Drawing Algorithm without Division Operations}},

author = {
Fung, Khun Yee
 and 
Nicholl, Tina M.
 and 
Dewdney, A. K.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130267}

}
                
@article{
10.1111:1467-8659.1130311,

journal = {Computer Graphics Forum},
title = {{
Composing Hierarchically Structured Images}},

author = {
Patterson, John W.
 and 
Cockton, Gilbert
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130311}

}
                
@article{
10.1111:1467-8659.1130299,

journal = {Computer Graphics Forum},
title = {{
Area Sampling Buffer: Tracing Rays with Z-Buffer Hardware}},

author = {
Sung, Kelvin
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130299}

}
                
@article{
10.1111:1467-8659.1130279,

journal = {Computer Graphics Forum},
title = {{
Accurate Image Generation and Interactive Image Editing with the A-buffer}},

author = {
Lau, Wing Hung
 and 
Wiseman, Neil
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130279}

}
                
@article{
10.1111:1467-8659.1130289,

journal = {Computer Graphics Forum},
title = {{
Adaptive Sampling of Area Light Sources in Ray Tracing Including Diffuse Interreflection}},

author = {
Kok, Arjan J. F.
 and 
Jansen, Frederik W.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130289}

}
                
@article{
10.1111:1467-8659.1130333,

journal = {Computer Graphics Forum},
title = {{
Reference, Synthesis and Constraint Satisfaction*}},

author = {
Pineda, Luis A.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130333}

}
                
@article{
10.1111:1467-8659.1130023,

journal = {Computer Graphics Forum},
title = {{
Pandora: An Experiment in Distributed Multimedia}},

author = {
King, Tony
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130023}

}
                
@article{
10.1111:1467-8659.1130321,

journal = {Computer Graphics Forum},
title = {{
Computing Dynamic Changes to BSP Trees}},

author = {
Chrysanthou, Y.
 and 
Slater, M.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130321}

}
                
@article{
10.1111:1467-8659.1130367,

journal = {Computer Graphics Forum},
title = {{
Realistic Generation and Real Time Animation of Images of the Human Colon}},

author = {
Haritsis, Angelo
 and 
Gillies, Duncan
 and 
Williams, Christopher
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130367}

}
                
@article{
10.1111:1467-8659.1130357,

journal = {Computer Graphics Forum},
title = {{
The Graphical Translation of English Text into Signed English in the Hand Sign Translator System}},

author = {
Holden, E.J.
 and 
Roy, G.G.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130357}

}
                
@article{
10.1111:1467-8659.1130345,

journal = {Computer Graphics Forum},
title = {{
A Development Environment for Constructing Graph-Based Editing Tools}},

author = {
Chen, M.
 and 
Townsend, P.
 and 
Wang, C.Y.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130345}

}
                
@article{
10.1111:1467-8659.1130381,

journal = {Computer Graphics Forum},
title = {{
A CAD System for Color Design of a Car}},

author = {
Oshima, Tetsuya
 and 
Yuasa, Shinji
 and 
Sakanoshita, Ken-ichi
 and 
Ogata, Yoshinori
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130381}

}
                
@article{
10.1111:1467-8659.1130391,

journal = {Computer Graphics Forum},
title = {{
Two-manifold cell-decomposition of r-sets.}},

author = {
Falcidieno, Bianca
 and 
Ratto, Ornella
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130391}

}
                
@article{
10.1111:1467-8659.1130405,

journal = {Computer Graphics Forum},
title = {{
Equidistant Smoothing of Polyhedra with Arbitrary Topologies}},

author = {
Ma, Lizhuang
 and 
Liang, Youdong
 and 
Peng, Qunsheng
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130405}

}
                
@article{
10.1111:1467-8659.1130035,

journal = {Computer Graphics Forum},
title = {{
Rendering NURB Regions For 2D Animation}},

author = {
Willis, Philip
 and 
Oddy, Robert
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130035}

}
                
@article{
10.1111:1467-8659.1130425,

journal = {Computer Graphics Forum},
title = {{
A Simple Description of Complex Curves}},

author = {
Bouras, A.
 and 
Shariat, B.
 and 
Vandorpe, D.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130425}

}
                
@article{
10.1111:1467-8659.1130045,

journal = {Computer Graphics Forum},
title = {{
Modeling with Time and Events in Computer Animation}},

author = {
Kalra, Devendra
 and 
Barr, Alan H.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130045}

}
                
@article{
10.1111:1467-8659.1130435,

journal = {Computer Graphics Forum},
title = {{
Interactive Shape Control of Interpolating B-splines}},

author = {
Krokos, M. A.
 and 
Slater, M.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130435}

}
                
@article{
10.1111:1467-8659.1130415,

journal = {Computer Graphics Forum},
title = {{
Fractals and Solid Modeling}},

author = {
Groller, Eduard
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130415}

}
                
@article{
10.1111:1467-8659.1130449,

journal = {Computer Graphics Forum},
title = {{
Normal orientation methods for 3D offset curves, sweep surfaces and skinning}},

author = {
Siltanen, Pekka
 and 
Woodward, Charles
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130449}

}
                
@article{
10.1111:1467-8659.1130059,

journal = {Computer Graphics Forum},
title = {{
Simulation of Facial Muscle Actions Based on Rational Free Form Deformations}},

author = {
Kalra, Prem
 and 
Mangili, Angelo
 and 
Thalmann, Nadia Magnenat
 and 
Thalmann, Daniel
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130059}

}
                
@article{
10.1111:1467-8659.1130071,

journal = {Computer Graphics Forum},
title = {{
HAGI, a High-level Application/Graphics Interface}},

author = {
Hsu, Y. H.
 and 
Kuo, Y. S.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130071}

}
                
@article{
10.1111:1467-8659.1130081,

journal = {Computer Graphics Forum},
title = {{
An Object-Oriented View of the User Interface}},

author = {
Zhou, Tom Z.-Y.
 and 
Kubitz, William J.
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130081}

}
                
@article{
10.1111:1467-8659.1130093,

journal = {Computer Graphics Forum},
title = {{
SX/Tools - An Open Design Environment for Adaptable Multimedia User Interfaces}},

author = {
Kuhme, Thomas
 and 
Schneider-Hufschmidt, Matthias
},
year = {
1992},

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


ISSN = {1467-8659},

DOI = {
10.1111/1467-8659.1130093}

}

Browse

Recent Submissions

Now showing 1 - 39 of 39
  • Thumbnail Image
    Item
    An Open Model for Hypermedia and Its Application to Geographical Information Systems
    (Blackwell Science Ltd and the Eurographics Association, 1992) Hall, W.; Simmons, D.
    This paper describes the design and implementation of a multimedia information management environment that is based on an open model for hypermedia. The model, known as Microcosm, is currently implemented in Microsoft Windows and supports many different media types. The open nature of the model and the separation of the links from the data, allows links to be applied across any application running under Windows or the OS/2 version 2 desktop, thus creating a truly integrated environment. One example, which is, discussed in the paper, is the integration of a hypermedia database with a geographical information system. The paper also discusses the application of novel interfaces to dynamic media within a hypermedia system, including the use of moving icons (micons).
  • Thumbnail Image
    Item
    Stochastic Motion-Motion Under the Influence of Wind
    (Blackwell Science Ltd and the Eurographics Association, 1992) Shinya, Mikio; Fournier, Alain
    Stochastic approaches are very effective for modelling natural phenomena. This paper presents a motion model based on a stochastic process as well as physics, and proposes motion synthesis techniques for stochastic motion-motion under the influence of wind.The motion synthesis process is modelled by a cascade system of three components: wind model, dynamic model, and deformation model. Wind models produce spatio-temporal wind velocity fields using the power spectrum and auto-correlation of wind, just like fractal geometry. Dynamic models describe the dynamic response of the systems, using equation systems or response functions. Deformation models produce deformed shapes of objects according to the geometric models of the objects and the results of the dynamic systems.The biggest advantage of the model is its generality and consistency. The model is applicable to most of the existing trees and grass models, including structural models, particle systems, impressionist models, and 3D texture. It is demonstrated that the coupling of stochastic approaches and physically-based approaches can synthesize realistic motion of trees, grass and snow with modest computational cost.
  • Thumbnail Image
    Item
    A Functional Approach to the Visual Simulation of Gaseous Turbulence
    (Blackwell Science Ltd and the Eurographics Association, 1992) Sakas, Georgios; Westermann, Rudiger
    This paper presents a functional method for the visual simulation of 2-D or 3-D turbulent gaseous motion by using time-varying fractals. The used function incorporates results from the"spectral theory of turbulence", thereby providing a physics-based approach adapted to the needs of computer graphics. The involved turbulence function is band-limited, continuous, differentiable, anisotrop, and smooth, provides different fractal dimensions along each axis, may be evaluated locally with different parameters, and requires only minimal storage space, thus supporting an implementation on large parallel processing networks with small nodes. Inhomogeneity in the form of local disturbances of the turbulence field may also be easily considered. The parameters used to describe turbulent motion are rather intuitive, so that they may be utilized easily by users. Examples for modeling different types of clouds and fire are given.
  • Thumbnail Image
    Item
    Template-Based Volume Viewing
    (Blackwell Science Ltd and the Eurographics Association, 1992) Yagel, Roni; Kaufman, Arie
    We present an efficient three-phase algorithm for volume viewing that is based on exploiting coherency between rays in parallel projection. The algorithm starts by building a ray-template and determining a special plane for projection - the base-plane. Parallel rays are cast into the volume from within the projected region of the volume on the base-plane, by repeating the sequence of steps specified in the ray-template. We carefully choose the type of line to be employed and the way the template is being placed on the base-plane in order to assure uniform sampling of the volume by the discrete rays. We conclude by describing an optimized software implementation of our algorithm and reporting its performance.
  • Thumbnail Image
    Item
    A Unified Approach for Physical and Geometric Modeling for Graphics and Animation
    (Blackwell Science Ltd and the Eurographics Association, 1992) Essa, Irfan A.; Sclaroff, Stan; Pentland, Alex
    We present a unified approach for geometric and physical modeling using implicit functions, for application to graphics and animation. This method extends previously proposed techniques, and allows the standard finite element method to be directly combined with geometric modeling, resulting in quick calculation of an object s mass and stiffness matrices, and its vibration modes and frequencies. Because the approach is based on an implicitfunction representation, it allows very fast collision detection and characterization. Examples of complex physical and geometric modeling are presented.
  • Thumbnail Image
    Item
    The Visualization Input Pipeline - Enabling Semantic Interaction in Scientific Visualization
    (Blackwell Science Ltd and the Eurographics Association, 1992) Felger, W.; Schroder, F.
    Scientific Visualization systems are primarily output-oriented, Users can specify and change parameters that are controlling the visualization process, which will result in different data representations or images respectively. But no mechanism is provided to really interact with the application data (semantic interaction) that has been changed step by step by the process of visualization.In this paper general concepts are elaborated and presented to achieve semantic interaction in dataflow environments for Scientific Visualization.
  • Thumbnail Image
    Item
    Radiosity in Flatland
    (Blackwell Science Ltd and the Eurographics Association, 1992) Heckhert, Paul S.
    The radiosity method for the simulation of interreflection of light between diffuse surfaces is such a common image synthesis technique that its derivation is worthy of study. We here examine the radiosity method in a two dimensional, flatland world. It is shown that the radiosity method is a simple finite element method for the solution of the integral equation governing global illumination. These two-dimensional studies help explain the radiosity method in general and suggest a number of improvements to existing algorithms. In particular, radiosity solutions can be improved using a priori discontinuity meshing, placing mesh boundaries on discontinuities such as shadow edges. When discontinuity meshing is used along with piecewise-linear approximations instead of the current piecewise-constant approximations, the accuracy of radiosity simulations can be greatly increased.
  • Thumbnail Image
    Item
    An adaptive Discretization Method For Radiosity
    (Blackwell Science Ltd and the Eurographics Association, 1992) Languenou, Eric; Bouatouch, Kadi; Tellier, Pierre
    When using radiosiiy, the visual quality of the rendered images strongly depends on the method employed for discretizing the scene into patches. A too fine discretization may give rise to artifacts, while with a coarse discretization areas with high radiosity gradient may appear. To overcome these problems, the discretization must adapt to the scene. That is, the interaction between two patches must account for the distance between them as well as their surface area. In other words, surfaces far away are discretized less finely than nearby surfaces. These aspects are considered by the new adaptive discretiration method described in this paper. It performs both discretization and system resolution at each iteration of the shooting process, allowing then interactivity.
  • Thumbnail Image
    Item
    Fast Generation and Surface Structuring Methods for Terrain and Other Natural Phenomena
    (Blackwell Science Ltd and the Eurographics Association, 1992) Koh, Eng-Kiat; Hearn, D. D.
    Fractal geometry has proven to be a powerful tool for modeling natural phenomena. Using discrete approximations to fractional Brownian motion over a finite grid plane, computer graphics terrain-rendering algorithms are able to generate highly realistic topographical displays. Similar procedures can be applied to model other natural phenomena, such as clouds and water. Two important considerations in these algorithms are computational efficiency and the ability to control macroscopic surface features. Here we introduce a technique for structuring surface features so as to conform to a specified"elevation" envelope. We also present methods for implementing this technique using a recursive random midpoint-displacement procedure.
  • Thumbnail Image
    Item
    The Parametric Differential Method: An Alternative to the Calculation of Form Factors
    (Blackwell Science Ltd and the Eurographics Association, 1992) Baranoski, Gladimir V. Guimaraes
    The parametric differential method calculates the form factors without using approximations by polygons. Because of this it contributes to the improvement of the realism of the images synthesised through the radiosity method. This paper presents the most important characteristics of the parametric differential method as well as the results concerning its accuracy. Comparison of the form factors found using the new algorithm has been made with those analytically found.
  • Thumbnail Image
    Item
    Affine Texture Mapping and Antialiasing Using Integer Arithmetic
    (Blackwell Science Ltd and the Eurographics Association, 1992) Nehlig, P.; Ghazanfarpour, D.
    Texture mapping techniques are very useful for generating more realistic images. However, texture compression, generally induced by geometric transformations, is at the origin of aliasing artifacts especially the well-known"moire" patterns. Two discrete affine texture mapping methods based exclusively on integer arithmetic are presented here. This original approach of discrete affine mapping is adequate for antialiasing in the case of compressed textures.
  • Thumbnail Image
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    Modelling the Texture of Paint
    (Blackwell Science Ltd and the Eurographics Association, 1992) Cockshott, Tunde; Patterson, John; England, David
  • Thumbnail Image
    Item
    Visual Composition and Multimedia
    (Blackwell Science Ltd and the Eurographics Association, 1992) de Mey, Vicki; Breiteneder, Christian; Dami, Laurent; Gibbs, Simon and Tsichritzis, Dennis
    Multimedia applications can be seen as sets of autonomous parts, independent yet capable of working together. This assumption allows for the construction of multimedia applications in a"connectionist" fashion. In this paper we describe mechanisms for the visual composition of multimedia applications. These mechanisms allow for quick and flexible application construction by direct manipulation with reference to multiple composition models. An object-oriented framework for multimedia systems will be introduced throughout the paper.
  • Thumbnail Image
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    The Input Model of Standard Graphics Systems Revisited by Formal Specification
    (Blackwell Science Ltd and the Eurographics Association, 1992) Faconti, Giorgio P.; Zani, Nicola; Paterno , Fabio
    This paper describes the specification of an input model for graphics systems. The initial aim of the work reported in this paper was to revise the input model adopted by graphics standards by means of formal specification techniques in order to acquire a deep knowledge of its capabilities, to eventually discover errors and to develop improvements. Taking into account similar works done in this area by others and considering a number of major issues related to input recently discussed within the graphics community, a new model is being proposed that addresses the very key concepts of parallelism, extensibility and reconfigurability. The model is based upon composition operations defined over basic components specified as a set of concurrent processes. Composition operations and process definitions have been formally specified by using the LOTOS notation and investigated by means of the LOTOS Interactive Tools Environment. In the first part of the paper, the input model of graphics standards is shortly examined in the light of the results so far achieved by related works on formal specification of computer graphics systems. Subsequently, an improved model is presented. Finally, its capability of simulating the traditional operating modes of logical input devices and a methodology for defining new operating modes is demonstrated.
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    A line clipping algorithm and its analysis
    (Blackwell Science Ltd and the Eurographics Association, 1992) Krammer, Gergely
    One of the classical problems of Computer Graphics: line clipping against a rectangle is revisited. Coordinate raster refinement and some unusual forms of the parametric equation of the line are used to develop formulae for a line clipping algorithm. The algorithm is first presented in a form, where clarity of presentation is the prime concern. It is then transformed into one big nested branch, which after optimisation is assumed to be the most efficient form with a heavy cost on size. It is assumed that any mathematical consideration of the clipping problem would after a similar optimisation lead to a branching structure of equal complexity and speed. Line clipping thus belongs to the class of problems for which after a proper mathematical and logical analysis automatic program transformations may do the rest.This work has been supported by a grant from the Hungarian Academy of Sciences, Project No. OTKA 2572/1991
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    A Run-Length Slice Line Drawing Algorithm without Division Operations
    (Blackwell Science Ltd and the Eurographics Association, 1992) Fung, Khun Yee; Nicholl, Tina M.; Dewdney, A. K.
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    Composing Hierarchically Structured Images
    (Blackwell Science Ltd and the Eurographics Association, 1992) Patterson, John W.; Cockton, Gilbert
    This paper begins by examining the classical raster-based composition model, establishing its weakness, and developing a new composition algebra based on line drawing. It then examines the role of composition in the Hierarchical Display Model, demonstrates that the forms of composition assumed in this model are inadequate to deal correctly with the interactions of two-dimensional representations of three-dimensional objects, and shows that our composition algebra resolves this difficulty. The composition steps required can be packaged with the use of a single attribute which constrains the apparent order of composition. This attribute is associated with the object which is to be taken out of order , obviating any needsfor layers.
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    Area Sampling Buffer: Tracing Rays with Z-Buffer Hardware
    (Blackwell Science Ltd and the Eurographics Association, 1992) Sung, Kelvin
    An algorithm that allows the use of z-buffer hardware in assisting area sampling for a ray tracing style renderer is described. The implementation issues involved in discretizing the sampling area and light source area are discussed and solutions are proposed. The effects of the hardware-assisted ray tracing approach on frame-buffer systems and image synthesis processes are considered.
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    Accurate Image Generation and Interactive Image Editing with the A-buffer
    (Blackwell Science Ltd and the Eurographics Association, 1992) Lau, Wing Hung; Wiseman, Neil
    The A-buffer suggested by Carpenter [2] is a hidden surface removal method which deals with arbitrary overlapping edges in a pixel. In this paper, we suggest a way of increasing the subpixel resolution by storing the bitmask index rather than the bitmask. This allows much more accurate images to be generated while at the same time, minimising memory usage. It also allows zooming to reveal more information. We also suggest an enhancement to the A-buffer by allowing the creation of dynamic objects. These dynamic objects can then be edited (deleted, moved, etc.) interactively as image modification and assembly is going on. This new buffer forms part of the image composition system we have been working on.
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    Adaptive Sampling of Area Light Sources in Ray Tracing Including Diffuse Interreflection
    (Blackwell Science Ltd and the Eurographics Association, 1992) Kok, Arjan J. F.; Jansen, Frederik W.
    Ray tracing algorithms that sample both the light received directly from light sources and the light received indirectly by diffuse reflection from other patches, can accurately render the global illumination in a scene and can display complex scenes with accurate shadowing. A drawback of these algorithms, however, is the high cost for sampling the direct light which is done by shadow ray testing. Although several strategies are available to reduce the number of shadow rays, still a large number of rays will be needed, in particular to sample large area light sources. An adaptive sampling strategy is proposed that reduces the number of shadow rays by using statistical information from the sampling process and by applying information from a radiosity preprocessing. A further reduction in shadow rays is obtained by applying shadow pattern coherence, i.e. reusing the adaptive sampling pattern for neighboring sampling points.
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    Reference, Synthesis and Constraint Satisfaction*
    (Blackwell Science Ltd and the Eurographics Association, 1992) Pineda, Luis A.
    In this paper we discuss two kinds of constraint satisfaction problems that arise in the context of geometric modelling, In particular in the modification of 2-D wire-frame diagrams that are subject to an arbitrary number of geometrical and topological constraints. We argue that problems in this domain can be classified in two categories that we shall call problems of reference and problems of synthesis. Since Sutherland s Sketchpad program [16], a large number of systems have addressed constraint satisfaction in terms of the representation of constraints sets as equation systems, which in turn are solved by numerical methods like local propagation, relaxation and Gaussian elimination. Here, we present an alternative framework. We argue that conceptualising constraint satisfaction as symbolic rather than"numerical" problems helps to clarify the notion of"constraint", simplify solution methods, and to explain the intuitive inferential processes underlying the modification of drawings in the course of interactive drafting sessions. The theory presented in this paper has been tested with an experimental computer program called Graflog [5, 8, 9, 10, 11, 12]. The program has been implemented during the last four years, and has evolved through several stages. The current version is implemented in terms of two Unix-processes connected by Unix-pipes. The first is a"C" program running X windows, and handles the external aspects of the interaction. The second is a Prolog program supporting the representational structures and interpreters of the system.
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    Pandora: An Experiment in Distributed Multimedia
    (Blackwell Science Ltd and the Eurographics Association, 1992) King, Tony
    An experimental workstation is described which supports digital video and audio in a distributed environment, and which presents this functionality to the user through the medium of a video-extended implementation of the X Window System. The Pandora Workstation is built out of two quite separate parts. A standard UNIX machine (the Pandora Host) brings standard hardware and software computing resources to the system- a highly-specialised processing engine (Pandora s Box) handles the high-bandwidth, time-critical, and device-dependent processing. A 50 Mbit/second ATM network provides for real-time data communication within the system. Nineteen Pandora Workstations have been deployed within Olivetti Research Ltd and the Cambridge University Computer Laboratory, and are used routinely to run distributed applications including video mail, video conferencing, and real-time media delivery services.
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    Computing Dynamic Changes to BSP Trees
    (Blackwell Science Ltd and the Eurographics Association, 1992) Chrysanthou, Y.; Slater, M.
    This paper investigates a new method for dynamically changing Binary Space Partition (BSP) trees. A BSP tree representation of a 3D polygonal scene provides an ideal data structure for rapidly performing the hidden surface computations involved in changing the viewpoint. However, BSP trees have generally been thought to be unsuitable for applications where the geometry of objects in the scene changes dynamically. The purpose of this paper is to introduce a dynamic BSP tree algorithm which does allow for such changes, and which maintains the simplicity and integrity of the BSP tree representation. The algorithm is extended to include dynamic changes to shadows. We calibrate the algorithms by transforming a range of objects in a scene, and reporting on the observed timing results.
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    Realistic Generation and Real Time Animation of Images of the Human Colon
    (Blackwell Science Ltd and the Eurographics Association, 1992) Haritsis, Angelo; Gillies, Duncan; Williams, Christopher
    A simulator has been built to teach doctors the skill of handling a flexible endoscope for gastrointestinal investigations. Trainees use a dummy endoscope in which the control actions are transduced into voltages and sensed by the computer. The simulator computes the position and viewing direction of the endoscope within an internal model of the human colon. Then a renderer draws the view, reproducing as far as possible what would be seen during a real colonoscopy. Since the system must generate at least ten frames per second for realistic animation, standard rendering techniques, such as ray tracing, could not be used. Consequently a new method was devised, based on identifying coherent regions along each scan line which can be rendered by table lookup. The method allows shaded Lambertian surfaces to be drawn at a frame rate of 15 per second, using modest computing resources. Although several approximations were required in the analysis, the computer images of the internal surfaces of the human colon present a high degree of visual realism.
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    The Graphical Translation of English Text into Signed English in the Hand Sign Translator System
    (Blackwell Science Ltd and the Eurographics Association, 1992) Holden, E.J.; Roy, G.G.
    Signed English is a manual interpretation of English using fingerspelling and signs. A prototype of the Hand Sign Translator (HST) system was developed to graphically translate English into Signed English, using two-handed animation. The HST consists of a practical interface that aims to help users learn Signed English, and the translation process where English text is transformed into a series of images that represent corresponding signs. This paper describes the translation process which involves two stages- the input environment and the animation process. The input environment consists of text analysis in order to extract corresponding kinematic data from the database, named English-Sign Dictionary (ESD). The data is then used as an input to the animation process, Firstly, the skeleton models of keyframe images and their in-between poses are calculated. Secondly, appropriate volume models are applied in order to surround the surface of skin. Then the shapes that are suitable for painting are generated, and finally images are drawn and rendered using a smooth animation technique.
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    A Development Environment for Constructing Graph-Based Editing Tools
    (Blackwell Science Ltd and the Eurographics Association, 1992) Chen, M.; Townsend, P.; Wang, C.Y.
    Scientists and engineers use numerous kinds of graph notations to model various objects in the real world and their relationships in an abstract pictorial form. However, developing a specific graph editing tool for each of these notations is often very costly in terms of time and resources. This paper outlines a design of a suitable development environment for constructing graph-based editing tools, based on the requirements analysis of such an environment derived from a survey of more than 60 different graph notations.
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    A CAD System for Color Design of a Car
    (Blackwell Science Ltd and the Eurographics Association, 1992) Oshima, Tetsuya; Yuasa, Shinji; Sakanoshita, Ken-ichi; Ogata, Yoshinori
    We have developed a color CAD system which enables a color designer to evaluate and create body colors of a car on a graphic display and put this system into practical use. The system has three features- generating realistic images comparable to photography to satisfy the car designer s needs, through close analysis of the physical phenomena taking place in the real environment, reproducing the desired colors very accurately on a CRT monitor, through analysis of the CRT colorimetric characteristics of reproducing the specified colors in response to the input signals, and utilizing a parallel computer to generate realistic images at a high speed and to control colors through interactive operation. Application of the CAD system reported here to the field of color design made it possible to fully evaluate and create body colors by means of computer graphics, replacing the conventional method which requires the painting of clay models or prototype cars.
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    Two-manifold cell-decomposition of r-sets.
    (Blackwell Science Ltd and the Eurographics Association, 1992) Falcidieno, Bianca; Ratto, Ornella
    This paper discusses the relationships studied between manifold solids and r-sets by defining an r-set as a decomposition in two-manifold cells. This decomposition is represented as a graph (Two-manifold Cell Decomposition graph TCD) in which each node corresponds to a 2 manifold component of the regular set, while each arc or hyperarc defines a non-manifold adjacency between components. The TCD model and data structure encoding it were designed in order to be compatible with a traditional boundary architecture.
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    Equidistant Smoothing of Polyhedra with Arbitrary Topologies
    (Blackwell Science Ltd and the Eurographics Association, 1992) Ma, Lizhuang; Liang, Youdong; Peng, Qunsheng
    Smoothing of polyhedron with arbitrary topology is an important issue in CAGD and CAD/CAM, but so far it is deemed to be difficult to smooth the complex corners of a polyhedron. In this paper, the concept of distance surfaces of a surface and a solid is introduced, and the incisive properties of such surfaces are addressed which provide a theoretical foundation for modifying a general corner. The method is based on making constricted volume and the maximum distance the volume can be constricted is given too. It is shown that by the proposed method in this paper any polyhedron can be G1 smoothed with quadraic and, sometimes toroidal surfaces. The new approach is suitable for engineering design and NC machining. The associated algorithm based on the classification theorem of corners is simple, fast and robust.
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    Rendering NURB Regions For 2D Animation
    (Blackwell Science Ltd and the Eurographics Association, 1992) Willis, Philip; Oddy, Robert
    We describe an accurate method of rendering by scan-conversion of closed regions bounded by NURBs, with particular comments on its application to computer-based 2D animation. It is shown that the method is fast, analytically accurate, and can be readily extended to include anti-aliasing and clipping.
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    A Simple Description of Complex Curves
    (Blackwell Science Ltd and the Eurographics Association, 1992) Bouras, A.; Shariat, B.; Vandorpe, D.
    In this paper, we propose a method of complex curves description, based on the use of standard primitives (curve arcs), inscribed in including boxes. This method simplifies the creation steps (curves are not defined with the help of control points), and the manipulation steps (using including boxes).This study constitutes an extension to our descriptive universal language, named"G", which is used in a general desig n environment, permitting the integration of various models (solids1, polyhedrons2, surfaces3 and fractals), in order to offer the adequate tools adapted to the problems to be solved, in a unique modeller.
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    Modeling with Time and Events in Computer Animation
    (Blackwell Science Ltd and the Eurographics Association, 1992) Kalra, Devendra; Barr, Alan H.
    In this paper, we present a general, systematic and consistent treatment of time and events for computer animation. We first formalize the concepts of events and create a time primitive called an event unit. We then present a succession of organization schemes to compose event units for generating complex motion sequences. We present a directed graph representation for the organization of time and events that suggests the form of an event-based time programming language. Details of implementation of a general event simulation system are given. Our approach provides a clean partitioning for the problem of motion design, a hierarchical scheme to compose motion behaviors from time primitives and a programming model for organizing animation. Traditional methods of kinematic controls and key frame interpolation are special cases of our general scheme. In addition, our treatment of events can be combined with kinematics, dynamics or constraint-based systems to generate powerful motion modeling systems.
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    Interactive Shape Control of Interpolating B-splines
    (Blackwell Science Ltd and the Eurographics Association, 1992) Krokos, M. A.; Slater, M.
    This paper presents a new methodfor providing interactive shape control of interpolating B-splines. The CAD designer can directly interact with geometric entities defined on the B-spline at any interpolated data point- shape adjustments can be performed either globally or locally. Our approach is based on B?-splines of order k (?,k ?1), i.e. ?-reparametrized, classical B-splines. The method presented can be easily generalised to surfaces defined either as tensor products or by using the skinning technique- interactive shape control can be provided in both surface parametric directions.
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    Fractals and Solid Modeling
    (Blackwell Science Ltd and the Eurographics Association, 1992) Groller, Eduard
    Trying to combine fractal geometry and solid modeling seems to be a contradiction in itself, In this paper a new type of 3D objects is presented that accomplishes this combination in a specific way. Objects with a fractal macro structure and a 3D solid micro structure can be specified and rendered efficiently by using context free, attribute, geometric grammars. This new object type can be incorporated into the CSG-modeling technique (Constructive Solid Geometry) in two ways: a) using CSG for the specification of the micro structure of the new object type, b) using these fractal like objects as a new type of primitive in the CSG model. Ray tracing is used for generating high quality images of these geometrically complex objects.
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    Normal orientation methods for 3D offset curves, sweep surfaces and skinning
    (Blackwell Science Ltd and the Eurographics Association, 1992) Siltanen, Pekka; Woodward, Charles
    Computing an offset curve to a 3D curve involves the basic problem of normal orientation in space. The same thing is encountered when interpolating surfaces with 3D sweep or skinning methods. Different methods for normal orientation are discussed an this article. A new method is presented for normal orientation on general parametric curves.
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    Simulation of Facial Muscle Actions Based on Rational Free Form Deformations
    (Blackwell Science Ltd and the Eurographics Association, 1992) Kalra, Prem; Mangili, Angelo; Thalmann, Nadia Magnenat; Thalmann, Daniel
    This paper describes interactive facilities for simulating abstract muscle actions using Rational Free Form Deformations (RFFD). The particular muscle action is simulated as the displacement of the control points of the control-unit for an RFFD defined on a region of interest. One or several simulated muscle actions constitute a Minimum Perceptible Action (MPA), which is defined as the atomic action unit, similar to Action Unit (AU) of the Facial Action Coding System (FACS), to build an expression.
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    HAGI, a High-level Application/Graphics Interface
    (Blackwell Science Ltd and the Eurographics Association, 1992) Hsu, Y. H.; Kuo, Y. S.
    HAGI is an object-oriented graphics system developed on top of the X window system. In addition to providing facilities that structured graphics systems such as GKS usually have, HAGI supports a high- level graphics paradigm with the following features: * + In addition to graphical objects, the system provides a class of application objects with a higher level of abstraction than graphical objects. * + Graphics manipulation operations can be issued simplyfrom application objects without explicitly referring to specific graphical objects. Thus graphics manipulation appears to be transparent to application programmers. * + Graphical objects are designed to encompass more semantics, thus are at a level close to the application. For example, they useflexible visual objects to determine their visual appearance.HAGI provides such a high-level application/graphics interface by maintaining a dependency relationship between graphical objects and application objects.
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    An Object-Oriented View of the User Interface
    (Blackwell Science Ltd and the Eurographics Association, 1992) Zhou, Tom Z.-Y.; Kubitz, William J.
    The object-oriented view of the user interface presented here is a model of object responsibilities-sharing and cooperation for a typical user interface. The model regards the user interface as a three-layer architecture, with the application contributing to one of the layers called the application exposure, The model seeks to promote user interface software reuse by coupling the user interface and the application with well-defined message protocols, by properly allocating user interfacefunctions to the layers so as to reduce and discipline their dependencies, and byfactoring complex abstractions into reusable secondary components.
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    SX/Tools - An Open Design Environment for Adaptable Multimedia User Interfaces
    (Blackwell Science Ltd and the Eurographics Association, 1992) Kuhme, Thomas; Schneider-Hufschmidt, Matthias
    In this paper a brief review of user interface management systems (UIMSs) and their advantages is given. Shortcomings of current UIMSs and open requirements imposed by industrial application areas are outlined. Among the most important requirements are uniform design mechanisms independent of interaction media, techniques, and styles as well as a straight forward end-user adaptability of user interfaces.A new approach to interactive interface construction, called"direct composition", is introduced. In this approach all interface objects contain the means for their own modification and design and therefore offer consistent interaction techniques for both the construction and usage of user interfaces. Moreover, end-user adaptability is an inherent feature of direct composition interfaces.The user interface design environment SX/Tools is described to exemplify specific properties of user interface management systems following the principle of direct composition. The impacts of direct composition on user interface design include a uniform interface development process covering tool development, interface development, and"on-usage" interface adaptation. It is argued that the direct composition approach can overcome many of the problems with traditional UIMSs.