Radiosity Abstracts 1989-1996

Abstract: The following topics were dealt with: The treatment of radiation heat transfer in the computer modelling of crystal growth from the melt requires the net heat flux q/sub i/ for the boundary conditions of the temperature field, and the view factors f/sub ij/ for the radiative exchange between surfaces A/sub i/, A/sub j/ of an enclosure, i, j=1 to N. Different methods can be used to determine q/sub i/: the radiosity method, a direct and Gebhart's method. A new proof of the equivalence of Gebhart's method with the other two is given. The concept of view factors for gray-diffuse surfaces is briefly surveyed. For a simplified enclosure describing the interior part of a vertical Bridgman furnace the f/sub ij/ are determined within an analytical approximation. The convergence of this method is investigated for two singular cases: (i) A/sub i/ and A/sub j/ have a common edge, (ii) A/sub i/ is self-viewing. As the main result we present, for a coaxial enclosure partitioned into rings, the f/sub ij/ in closed form by means of the Sparrow-Moon area-contour integral. It is further shown, that Sparrow's double contour integral is not generally applicable, if shadowing effects are present. (48 Refs.)
Classification: A6150C (Physics of crystal growth); A0130Q (Reports, dissertations, theses); A8110F (Crystal growth from melt) Thesaurus: Crystal growth from melt; Heat radiation
Free Terms: Radiation heat transfer; Computer modelling; Crystal growth; Heat flux; Radiative exchange; Radiosity method; Gebhart's method; View factors; Gray-diffuse surfaces; Vertical Bridgman furnace; Sparrow-Moon area-contour integral; Shadowing effects

95-2
Doc Type: Conference Paper
Title: Temporal coherence in progressive radiosity Authors: Tost, D.; Pueyo, X.
Affiliation: Software Dept., Polytechnical Univ. of Catalonia, Barcelona, Spain
Conf. Title: Visualization and Intelligent Design in Engineering and Architecture
p. 77-90
Editors: Connor, J.J.; Hernandez, S.; Murthy, T.K.S.; Power, H.
Publisher: Comput. Mech. Publications
Southampton, UK
Date: 1993 656 pp.
Country of Publication: UK
ISBN: 1 85312 227 0
Language: English
Conf. Date: 28-30 April 1993
Conf. Loc: Southampton, UK
Treatment: Theoretical/Mathematical

Abstract: We present a study of the use of temporal coherence in radiosity algorithms. We underline the fact that this may be used even in static environments given that the behavior of a radiosity algorithm, when computing the form-factors of a surface is the same as the behavior of an algorithm computing visibility for a sequence of view points corresponding to a linear movement. We study the proposed solutions for dynamic environments. Finally, we propose an algorithm for dynamic environments which target is to reach a wide use of temporal coherence. (18 Refs.)
Classification: C6130B (Graphics techniques); C4240 (Programming and algorithm theory)
Thesaurus: Algorithm theory; Brightness; Computer graphics; Light coherence
Free Terms: Progressive radiosity; Temporal coherence; Radiosity algorithms; Static environments; Surface form factors; Dynamic environments

95-3
Doc Type: Conference Paper
Title: The use of visibility coherence for radiosity computation
Authors: Pueyo, X.
Affiliation: Dept. Llenguatges i Sistemes Informatics, Univ.
Politecnica de Catalunya, Barcelona, Spain
Conf. Title: Visualization and Intelligent Design in Engineering and Architecture
p. 17-28
Editors: Connor, J.J.; Hernandez, S.; Murthy, T.K.S.; Power, H.
Publisher: Comput. Mech. Publications
Southampton, UK
Date: 1993 656 pp.
Country of Publication: UK
ISBN: 1 85312 227 0
Language: English
Conf. Date: 28-30 April 1993
Conf. Loc: Southampton, UK
Treatment: Theoretical/Mathematical

Abstract: Coherence has been widely used to improved the performance of visibility computation in traditional hidden line/surface algorithms. The appearance of radiosity algorithms has increased the importance of computing efficiently the visibility function given that it is performed a lot of times to obtain a single static image. We develop a characterization of the uses of coherence in radiosity algorithms and give a brief and schematic description of proposed algorithms using them. (9 Refs.)
Classification: C6130B (Graphics techniques); C5260B (Computer vision and image processing techniques)
Thesaurus: Brightness; Coherence; Computer graphics; Image processing; Visibility
Free Terms: Radiosity computation; Visibility coherence; Performance; Hidden line algorithms; Hidden surface algorithms; Radiosity algorithms; Visibility function; Single static image

95-4
Doc Type: Conference Paper
Title: Generating plants for computer graphics
Authors: Benes, B.
Affiliation: Dept. of Comput. Sci., Tech. Univ., Prague, Czech Republic
Conf. Title: Winter School of Computer Graphics and CAD Systems 94 p. 221-3
Publisher: Univ. West Bohemia
Pilsen, Czech Republic
Date: 1994 233 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 192 2
Language: English
Conf. Date: 19-20 Jan. 1994
Conf. Loc: Pilsen, Czech Republic
Treatment: Practical

Abstract: Computer graphics focuses its activities mostly on the modelling of the real world. It means in practice to find a model of the modelled object which can be interpreted by means of computer graphics. There has been a lot of progress in this research. We have fundamental models of light of reflecting, and are able to simulate real surfaces. To visualise these models we can use on of two principal methods: ray tracing or radiosity. There are several open problems in computer graphics. One of these is the general problem of time. These methods are very time consuming. This time depends on the modeled scene. The time needed for visualisation increase with the number of modeled objects and can be strongly decreased with a smart algorithm or a good data. representation or speed hardware. A. Lindenmayer (1968) showed a structure of a parallel string rewriting system for the growth of living organisms in 1968. This method describes the geometry of a tree, but it was used for these purposes for the first time in 1984 in the work of Aono and Smith (A.R. Smith, 1984). The work presented continues in the work of Lindenmayer and P Pruzsinliiewicz (1986) at present. A focus of these works lies in the topology of trees and a geometry of these objects is showed in works of J. Bloomenthal (1985); P. Oppenheimer (1986); Y. Kawaguchi (1982). (7 Refs.)
Classification: C6130B (Graphics techniques); C4210L (Formal languages and computational linguistics); C1160 (Combinatorial mathematics) Thesaurus: Computer graphics; Ray tracing; Rewriting systems; Set theory
Free Terms: Computer graphics; Real world modelling; Real surface simulation; Ray tracing; Radiosity; Visualisation; Parallel string rewriting system; Living organisms; Tree geometry; Tree topology

95-5
Doc Type: Conference Paper
Title: Parallel progressive radiosity with parallel visibility computations
Authors: Sturzlinger, W.; Wild, C.
Affiliation: Inst. for Comput. Sci., Johannes Kepler Univ., Linz, Austria
Conf. Title: Winter School of Computer Graphics and CAD Systems 94 p. 66-74
Publisher: Univ. West Bohemia
Pilsen, Czech Republic
Date: 1994 233 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 192 2
Language: English
Conf. Date: 19-20 Jan. 1994
Conf. Loc: Pilsen, Czech Republic
Treatment: Theoretical/Mathematical

Abstract: The radiosity method models the interaction of light between diffuse reflecting surfaces, thereby accurately predicting global illumination effects. Due to the high computational effort to calculate the transfer of light between surfaces and the memory requirements for the scene description, a distributed, parallelized version of the algorithm is needed for scenes consisting of thousands of surfaces. We present a distributed, parallel radiosity algorithm, which can subdivide the surfaces adaptively. Additionally we present a scheme for parallel visibility calculations. Adaptive load redistribution is also discussed. (14 Refs.)
Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6150N (Distributed systems software)
Thesaurus: Brightness; Light reflection; Parallel algorithms; Realistic images; Rendering [computer graphics]; Visibility
Free Terms: Parallel progressive radiosity; Parallel visibility computations; Light interaction; Diffuse reflecting surfaces; Global illumination effects; Computational effort; Memory requirements; Distributed parallelized algorithm; Scene description; Light transfer; Adaptive load redistribution

95-6
Doc Type: Conference Paper
Title: Cubic Monte Carlo radiosity
Authors: Elias, P.; Feda, M.; Ferschin, P.; Purathofer, W.
Affiliation: Dept. of Appl. Math., Comenius Univ., Bratislava, Slovakia
Conf. Title: Winter School of Computer Graphics and CAD Systems 94 p. 9-19
Publisher: Univ. West Bohemia
Pilsen, Czech Republic
Date: 1994 233 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 192 2
Language: English
Conf. Date: 19-20 Jan. 1994
Conf. Loc: Pilsen, Czech Republic
Treatment: Theoretical/Mathematical

Abstract: A revised radiosity method for curved surfaces is proposed, based on the Monte Carlo approach. In order to improve the accuracy of the solution, a smoothly reconstructed illumination function with selected discontinuities is used during the radiosity computation. The reconstructed function is used as a random number distribution for position sampling to overcome the constant radiosity assumption syndrome. Illumination information stored at the surface control points is used to preserve continuity of the illumination across the boundary of adjacent surfaces and to avoid Mach band effects. Implementation in Flatland is discussed. (18 Refs.)
Classification: C6130B (Graphics techniques); C1140G (Monte Carlo methods)
Thesaurus: Brightness; Computer graphics; Lighting; Monte Carlo methods Free Terms: Curved surfaces; Cubic Monte Carlo radiosity computation; Solution accuracy; Smoothly reconstructed illumination function; Discontinuities; Random number distribution; Position sampling; Constant radiosity assumption syndrome; Surface control points; Illumination continuity preservation; Adjacent surface boundaries; Mach band effects; Flatland

95-7
Doc Type: Conference Paper
Title: A synthetic mobile robot
Authors: Erard, P.-J.; Fuhrer, C.; Iff, L.
Affiliation: Inst. d'Inf. et Intelligence Artificielle, Neuchatel Univ., Switzerland
Conf. Title: Proceedings. Computer Animation '95
p. 30-4
Publisher: IEEE Comput. Soc. Press
Los Alamitos, CA, USA
Date: 1995 ix+221 pp.
Country of Publication: USA
ISBN: 0 8186 7062 2
CCC: 0 8186 7062 2/95/$04.00
Language: English
Conf. Date: 19-21 April 1995
Conf. Loc: Geneva, Switzerland
Conf. Sponsor: DIGIMEDIA; Swiss Nat. Res. Found.; Comput.
Graphics Soc.; Swiss Federal Inst. Technol.;
Univ. Geneva
Treatment: Application; Practical

Abstract: This paper presents a project who's goal is to make an animation simulating the activity of a mobile robot in a given environment. A parallel is drawn between animation and reactive programming, particularly with the concept of autonomous agent. The realised animation consists of a virtual world, the environment of the robot and the robot itself, as an agent acting in this world. The turning point of the project is the simulation of the sensors through which the simulated robot is supposed to see its environment. To implement this task, advanced techniques are used such as ray tracing and radiosity. An experimentation platform is designed based on the robot Nomad 200 and its simulator, with adjunction of interfaces for the virtual sensors and for the representation on the computer screen. (5 Refs.)
Classification: C6130B (Graphics techniques); C3390C (Mobile robots); C6185 (Simulation techniques)
Thesaurus: Computer animation; Digital simulation; Mobile robots Free Terms: Mobile robot simulation animation; Reactive programming; Autonomous agent; Virtual world; Ray tracing; Radiosity; Robot Nomad 200; Virtual sensors; Computer screen

95-8
Doc Type: Conference Paper
Title: Efficient realistic image synthesis by parallel Monte Carlo radiosity on transputers
Authors: Feda, M.; Purgathofer, W.
Affiliation: Inst. of Comput. Graphics, Tech. Univ. Wien, Austria Conf. Title: Transputer Applications and Systems'94. Proceedings of the 1994 World Transputer Congress
p. 54-62
Editors: de Gloria, A.; Jane, M.R.; Marini, D.
Publisher: IOS Press
Amsterdam, Netherlands
Date: 1994 xi+1009 pp.
Country of Publication: Netherlands
Language: English
Conf. Date: 5-7 Sept. 1994
Conf. Loc: Como, Italy
Conf. Sponsor: Transputer Consortium; SGS-Thomson
Microelectron.; Eur. Union; Italian Transputer
User Group
Treatment: Practical

Abstract: The radiosity algorithm is a powerful method for photorealistic rendering. Unfortunately, like for other global illumination algorithms, the computation time for radiosity is very high. Parallel implementations on transputers described up to now suffer from high communication overhead, because the scene representation required by radiosity is too complex to be stored at each transputer. This paper presents a new hierarchical data structure for radiosity computation on transputers. The data structure consists of a CSG tree and a boundary representation (BRep). The CSG tree represents the scene accurately, but requires only little memory. It can be stored at each transputer, and is used for visibility tests performed by ray tracing, while the boundary representation is used for storing the radiosities. The new data structure significantly reduces the communication overhead for parallel radiosity computation, and because of its hierarchical form it also speeds up the computation itself. (15 Refs.) Classification: C6130B (Graphics techniques); C5260B (Computer vision and image processing techniques); C1140G (Monte Carlo methods); C6120 (File organisation); C6150N (Distributed systems software); C5220P (Parallel architecture)
Thesaurus: Brightness; Image representation; Lighting; Monte Carlo methods; Parallel algorithms; Parallel architectures; Ray tracing; Realistic images; Rendering [computer graphics]; Transputer systems; Tree data structures; Visibility
Free Terms: Efficient realistic image synthesis; Parallel Monte Carlo radiosity; Transputers; Radiosity algorithm; Photorealistic rendering; Global illumination algorithms; Computation time; Parallel implementations; High communication overhead; Scene representation; Hierarchical data structure; CSG tree; Boundary representation; Memory; Visibility tests; Ray tracing; Radiosity storing

95-9
Doc Type: Conference Paper
Title: Parallel radiosity on transputers with low communication overhead
Authors: Feda, M.
Affiliation: Inst. of Comput. Graphics, Tech. Univ. Wien, Austria Conf. Title: Proceedings of the 2nd Austrian-Hungarian Workshop on Transputer Applications (KFKI-1995-2/M, N)
p. 62-70
Editors: Ferenczi, S.; Kacsuk, P.
Publisher: Hungarian Acad. Sci
Budapest, Hungary
Date: 1995 vii+282 pp.
Country of Publication: Hungary
Language: English
Conf. Date: 29 Sept.-1 Oct. 1994
Conf. Loc: Budapest, Hungary
Treatment: Application; Practical

Abstract: The radiosity algorithm is a powerful method for photorealistic rendering. Unfortunately, like for other global illumination algorithms, the computation time for radiosity is very high. Parallel implementations on transputers described up to now suffer from high communication overhead, because the scene representation required by radiosity is too complex to be stored at each transputer. This paper presents a new hierarchical data structure for radiosity computation on transputers. The data structure consists of a CSG tree and a boundary representation (BRep). The CSG tree represents the scene accurately but requires only little memory. It can be stored at each transputer, and is used for visibility tests performed by ray tracing, while the boundary representation is used for scoring the radiosities. The new data structure significantly reduces the communication overhead for parallel radiosity computation, and because of its hierarchical form it also speeds up the computation itself. (11 Refs.) Classification: C6130B (Graphics techniques); C1160 (Combinatorial mathematics); C4260 (Computational geometry); C5440 (Multiprocessing systems); C6120 (File organisation)
Thesaurus: Computational geometry; Data structures; Ray tracing; Rendering [computer graphics]; Transputer systems
Free Terms: Parallel radiosity; Transputers; Low communication overhead; Photorealistic rendering; Hierarchical data structure; CSG tree; Boundary representation; Visibility tests; Ray tracing; Communication overhead; Parallel radiosity computation

95-10
Doc Type: Conference Paper
Title: Fast display of radiosity images on the MP-1
Authors: Renaud, C.; Bricout, F.; Lepretre, E.
Affiliation: Lab. d'Inf. Fondamentale de Lille, Univ. des Sci. et Tech. de Lille Flandres Artois, Villeneuve d'Ascq, France
Conf. Title: Transputers '94. Proceedings of the International Conference
p. 110-19
Editors: Becker, M.; Litzler, L.; Tehel, M.
Publisher: IOS Press
Amsterdam, Netherlands
Date: 1994 x+316 pp.
Country of Publication: Netherlands
Language: English
Conf. Date: 21-23 Sept. 1994
Conf. Loc: Arc et Senans, France
Conf. Sponsor: Agence de Dev. Econ. du Doubs; Banque
Populaire de Franche Comte; CEE; CIEFOP;
INRIA; et al
Treatment: Application; Practical

Abstract: One way to reduce computation time required by high quality image synthesis algorithms is to use massively parallel machines. However, the data distribution induced forbid to use efficiently graphic specialised workstations for the visualisation. We present in this paper a massively parallel implementation of a display algorithm. This is a part of a general solution for progressive radiosity parallelisation on a massively parallel computer, the DEC MP-1. The results we got highlight the high efficiency of our approach. (15 Refs.)
Classification: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition); C5260B (Computer vision and image processing techniques); C5440 (Multiprocessing systems) Thesaurus: Image processing; Parallel machines
Free Terms: Radiosity images; High quality image synthesis algorithms; Massively parallel machines; Graphic specialised workstations; Visualisation; Massively parallel implementation; Display algorithm; Radiosity parallelisation; DEC MP-1

95-11
Doc Type: Conference Paper
Title: Parallel visibility computations for parallel radiosity
Authors: Sturzlinger, W.; Wild, C.
Affiliation: Inst. for Comput. Sci., Johannes Kepler Univ., Linz, Austria
Conf. Title: Parallel Processing: CONPAR 94 - VAPP VI. Third Joint International Conference on Vector and Parallel
Processing Proceedings
p. 405-13
Editors: Buchberger, B.; Volkert, J.
Publisher: Springer-Verlag
Berlin, Germany
Date: 1994 xvi+889 pp.
Country of Publication: Germany
Language: English
Conf. Date: 6-8 Sept. 1994
Conf. Loc: Linz, Austria
Treatment: Practical; Theoretical/Mathematical

Abstract: The radiosity method models the interaction of light between diffuse reflecting surfaces, thereby accurately predicting global illumination effects. Due to the high computational effort to calculate the transfer of light between surfaces and the memory requirements for the scene description, a distributed, parallelized version of the algorithm is needed for scenes consisting of thousands of surfaces. We present a distributed, parallel progressive radiosity algorithm. Then we parallelize the visibility calculations and analyze the results. (16 Refs.)
Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6150N (Distributed systems software); C4140 (Linear algebra)
Thesaurus: Brightness; Computer graphics; Light; Linear algebra; Parallel algorithms; Ray tracing
Free Terms: Parallel visibility computations; Parallel radiosity; Light interaction; Diffuse reflecting surfaces; Global illumination effects; High computational effort; Memory requirements; Scene description; Distributed algorithm; Parallel progressive radiosity algorithm; Visibility calculations

95-12
Doc Type: Conference Paper
Title: Progressive refinement radiosity on ring-connected multicomputers
Authors: Capin, T.K.; Aykanat, C.; Ozguc, B.
Affiliation: Dept. of Comput. Eng. & Inf. Sci., Bilkent Univ., Ankara, Turkey
Conf. Title: Proceedings. 1993 Parallel Rendering Symposium (IEEE Cat. No.93TH0592-6)
p. 71-6
Publisher: IEEE
New York, NY, USA
Date: 1993 112 pp.
Country of Publication: USA
ISBN: 0 8186 4920 8
CCC: 0 8186 4920 8/93/$3.00
Language: English
Conf. Date: 25-26 Oct. 1993
Conf. Loc: San Jose, CA, USA
Conf. Sponsor: IEEE; ACM SIGGRAPH
Treatment: Practical

Abstract: The progressive refinement method is investigated for parallelization on ring-connected multicomputers. A synchronous scheme, based on static task assignment, is proposed, in order to achieve better coherence during the parallel light distribution computations. An efficient global circulation scheme is proposed for the parallel light distribution computations, which reduces the total volume of concurrent communication by an asymptotical factor. The proposed parallel algorithm is implemented on a ring-embedded Intel's PSC/2 hypercube multicomputer. Load balance quality of the proposed static assignment schemes are evaluated experimentally. The effect of coherence in the parallel light distribution computations on the shooting patch selection sequence is also investigated. (10 Refs.) Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C4260 (Computational geometry); C6110P (Parallel programming); C6150N (Distributed systems software) Thesaurus: Brightness; Computational geometry; Parallel algorithms; Rendering [computer graphics]; Resource allocation
Free Terms: Load balance quality; Progressive refinement radiosity; Ring-connected multicomputers; Progressive refinement method; Synchronous scheme; Static task assignment; Parallel light distribution computations; Efficient global circulation scheme; Concurrent communication; Parallel algorithm; PSC/2 hypercube multicomputer; Shooting patch selection sequence

95-13
Doc Type: Conference Proceedings
Conf. Title: Proceedings of 1993 IEEE Parallel Rendering Symposium Publisher: IEEE
New York, NY, USA
Date: 1993 112 pp.
Country of Publication: USA
ISBN: 0 8186 4920 8
CCC: 93/$3.00
Language: English
Conf. Date: 25-26 Oct. 1993
Conf. Loc: San Jose, CA, USA
Conf. Sponsor: IEEE; ACM SIGGRAPH

Abstract: The following topics are dealt with: volume rendering; polygon methods; parallel techniques; terrain rendering; ray tracing; radiosity.
Classification: C6130B (Graphics techniques); C6110P (Parallel programming); C4240P (Parallel programming and algorithm theory); C4260 (Computational geometry)
Thesaurus: Brightness; Computational geometry; Parallel algorithms; Parallel programming; Ray tracing; Rendering [computer graphics] Free Terms: Volume rendering; Polygon methods; Parallel techniques; Terrain rendering; Ray tracing; Radiosity

95-14
Doc Type: Journal Paper
Title: Vision-an architecture for global illumination calculations
Authors: Slusallek, P.; Seidel, H.-P.
Affiliation: Comput. Graphics Group, Erlangen-Nurnberg Univ., Germany Journal: IEEE Transactions on Visualization and Computer Graphics
Vol: 1 Iss: 1 p. 77-96
Date: March 1995
Country of Publication: USA
ISSN: 1077-2626 CODEN: ITVGEA
CCC: 1077-2626/95/$04.00
Language: English
Treatment: Practical

Abstract: So far, the problem of global illumination calculation has almost exclusively been approached from an algorithmic point of view. We propose an architectural approach to global illumination. The proposed rendering architecture Vision is derived from a model of the physical rendering process, which is subsequently mapped onto an object-oriented hierarchy of classes. This design is powerful and flexible enough to support and exploit a large body of existing illumination algorithms for the simulation of various aspects of the underlying physical model. Additionally, the Vision architecture offers a platform for developing new algorithms and for combining them to create new rendering solutions. We discuss both abstract design as well as implementation issues. In particular, we give a detailed description of the global lighting subsystem and show how algorithms for path tracing, bidirectional estimators, irradiance caching, hierarchical radiosity, wavelet radiosity, and wavelet radiance have been implemented within Vision. (67 Refs.) Classification: C6130B (Graphics techniques); C6110J (Object-oriented programming); C6185 (Simulation techniques); C4190 (Other numerical methods)
Thesaurus: Brightness; Digital simulation; Lighting; Object-oriented methods; Ray tracing; Rendering [computer graphics]; Wavelet transforms
Free Terms: Global illumination calculations; Vision architecture; Rendering architecture; Physical rendering process; Object-oriented class hierarchy; Illumination algorithms; Simulation; Abstract design; Implementation issues; Global lighting subsystem; Path tracing; Bidirectional estimators; Irradiance caching; Hierarchical radiosity; Wavelet radiosity; Wavelet radiance

95-15
Doc Type: Conference Paper
Title: Multiresolution modeling for fast rendering
Authors: Heckbert, P.S.; Garland, M.
Affiliation: Dept. of Comput. Sci., Carnegie Mellon Univ., Pittsburgh, PA, USA
Conf. Title: Proceedings Graphics Interface '94
p. 43-50
Editors: Davis, W.A.; Joe, B.
Publisher: Canadian Inf. Process. Soc
Toronto, Ont., Canada
Date: 1994 viii+246 pp.
Country of Publication: Canada
ISBN: 0 9695338 3 7
Language: English
Conf. Date: 18-20 May 1994
Conf. Loc: Banff, Alta., Canada
Treatment: Practical; Theoretical/Mathematical

Abstract: Three dimensional scenes are typically modeled using a single, fixed resolution model of each geometric object. Renderings of such a model are often either slow or crude, however: slow for distant objects, where the chosen detail level is excessive, and crude for nearby objects, where the detail level is insufficient. What is needed is a multiresolution model that represents objects at multiple levels of detail. With a multiresolution model, a rendering program can choose the level of detail appropriate for the object's screen size so that less time is wasted drawing insignificant detail. The principal challenge is the development of algorithms that take a detailed model as input and automatically simplify it, while preserving appearance. Multiresolution techniques can be used to speed many applications, including real time rendering for architectural and terrain simulators, and slower, higher quality rendering for entertainment and radiosity. This paper surveys existing multiresolution modeling techniques and speculates about what might be possible in the future. (29 Refs.)
Classification: C6130B (Graphics techniques)
Thesaurus: Brightness; Real-time systems; Rendering [computer graphics]; Solid modelling
Free Terms: Multiresolution modeling; Fast rendering; Three dimensional scenes; Fixed resolution model; Geometric object; Distant objects; Rendering program; Screen size; Multiresolution techniques; Real time rendering; Terrain simulators; Architectural simulators; Entertainment; Radiosity; Multiresolution modeling techniques

95-16
Doc Type: Conference Paper
Title: Adaptive mesh refinement for the radiosity method
Authors: Phillips, S.; Worrall, A.; Willis, C.; Paddon, D.
Affiliation: Dept. of Comput. Sci., Bristol Univ., UK Conf. Title: EDUGRAPHICS '93. First International Conference on Graphics Education. COMPUGRAPHICS '93. Third
International Conference on Computational Graphics and
Visualization Techniques. Combined Proceedings
p. 178-86
Editors: Santo, H.P.
Publisher: Tech. Univ. Lisbon
Lisbon, Portugal
Date: 1993 ix+417 pp.
Country of Publication: Portugal
Language: English
Conf. Date: 5-10 Dec. 1993
Conf. Loc: Alvor, Portugal
Conf. Sponsor: Fundacao Luso-Americana para o
Desenvolvimento; Junta Nat. Investigacao
Cientifica e Tecnol
Treatment: Theoretical/Mathematical

Abstract: A hierarchical approach is used to represent the data structures for a triangular mesh for the radiosity method. The radiosity values are calculated using a ray tracing method for numerically evaluating the form factors. The radiosities are stored as patch vertex values which enables the mesh to be refined adaptively by evaluating the radiosity gradients across these vertex values. (9 Refs.)
Classification: C6130B (Graphics techniques); C6120 (File organisation); C4260 (Computational geometry)
Thesaurus: Brightness; Data structures; Ray tracing; Realistic images Free Terms: Adaptive mesh refinement; Radiosity method; Hierarchical approach; Data structures; Triangular mesh; Ray tracing method; Form factors; Patch vertex values

95-17
Doc Type: Conference Paper
Title: Global element method for radiosity calculation
Authors: Laszlo, S.-K.
Affiliation: Dept. of Process Control, Tech. Univ. Budapest, Hungary Conf. Title: EDUGRAPHICS '93. First International Conference on Graphics Education. COMPUGRAPHICS '93. Third
International Conference on Computational Graphics and
Visualization Techniques. Combined Proceedings
p. 171-7
Editors: Santo, H.P.
Publisher: Tech. Univ. Lisbon
Lisbon, Portugal
Date: 1993 ix+417 pp.
Country of Publication: Portugal
Language: English
Conf. Date: 5-10 Dec. 1993
Conf. Loc: Alvor, Portugal
Conf. Sponsor: Fundacao Luso-Americana para o
Desenvolvimento; Junta Nat. Investigacao
Cientifica e Tecnol
Treatment: Theoretical/Mathematical

Abstract: Traditional radiosity methods decompose surfaces into planar surface elements that can be supposed to have uniform radiosity and emittance, that is they approximate the unknown radiosity distribution by piecewise constant functions. This paper, on the other hand, develops a general framework to solve the radiosity equation numerically for any kind of function series approximation. Having derived the general formulae, three special cases are discussed: piecewise constant functions which lead to the traditional methods, linear finite elements and harmonic approximations where the basis functions are not of finite element type because they can approximate the radiosity distribution everywhere, and thus fall into the category of global element methods. Global element methods are able to work on the original geometry and they can be speeded up by effective techniques, such as fast Fourier transforms. (8 Refs.)
Classification: C6130B (Graphics techniques); C1130 (Integral transforms); C4185 (Finite element analysis); C4130 (Interpolation and function approximation); C4260 (Computational geometry) Thesaurus: Brightness; Computational geometry; Fast Fourier transforms; Finite element analysis; Function approximation; Series [mathematics]; Variational techniques
Free Terms: Radiosity calculation; Function series approximation; Piecewise constant functions; Linear finite elements; Harmonic approximations; Global element methods; Original geometry; Fast Fourier transforms

95-18
Doc Type: Journal Paper
Title: Parallel processing of the radiosity method
Authors: Paddon, D.; Chalmers, A.
Affiliation: Dept. of Comput. Sci., Bristol Univ., UK
Journal: Computer Aided Design
Vol: 26 Iss: 12 p. 917-27
Date: Dec. 1994
Country of Publication: UK
ISSN: 0010-4485 CODEN: CAIDA5
CCC: 0010-4485/94/12/0917-11$10.00
Language: English
Treatment: Practical

Abstract: The radiosity method gives one of the best solutions for synthesizing realistic images. However, the method is also the most computationally expensive. Using parallel computers will cut the time required to solve this problem, provided that care is taken in the design of the system. Various models of parallel computing are explored for both the gather radiosity method and the progressive refinement radiosity method. (14 Refs.)
Classification: C6130B (Graphics techniques); C5440 (Multiprocessing systems); C6110P (Parallel programming)
Thesaurus: Brightness; Parallel algorithms; Parallel machines;
Rendering [computer graphics]
Free Terms: Parallel processing; Radiosity method; Realistic images; Parallel computers; Parallel computing; Gather radiosity method; Progressive refinement radiosity method; Rendering

95-19
Doc Type: Journal Paper
Title: Data management scheme for parallel radiosity
Authors: Bouatouch, K.; Priol, T.
Affiliation: IRISA, Rennes, France
Journal: Computer Aided Design
Vol: 26 Iss: 12 p. 876-82
Date: Dec. 1994
Country of Publication: UK
ISSN: 0010-4485 CODEN: CAIDA5
CCC: 0010-4485/94/12/0876-07$10.00
Language: English
Treatment: Practical

Abstract: The radiosity method is a very demanding process in terms of computing and memory resources. To cope with these problems, parallel solutions have been proposed in the literature. A new parallel solution, based on the use of a shared virtual memory, is proposed. It is shown that this concept of SVM greatly simplifies the implementation of a parallel algorithm since distributed data are managed by the operating system. This new parallel radiosity algorithm has been implemented on an iPSC/2 hypercube using the KOAN SVM. The first results obtained with this algorithm are encouraging since the calculated efficiency curve is nearly linear. (24 Refs.) Classification: C6130B (Graphics techniques); C6110P (Parallel programming); C5440 (Multiprocessing systems); C6120 (File organisation)
Thesaurus: Brightness; Hypercube networks; Parallel algorithms; Rendering [computer graphics]; Shared memory systems; Virtual storage Free Terms: Data management scheme; Parallel radiosity; Memory resources; Parallel solution; Shared virtual memory; SVM; Parallel algorithm; Distributed data; Operating system; Radiosity algorithm; IPSC/2 hypercube; KOAN SVM

95-20
Doc Type: Conference Paper
Title: Parallel and distributed radiosity
Authors: Ng, A.
Affiliation: Dept. of Comput. Sci., Queen Mary & Westfield Coll., London, UK
Conf. Title: Proceedings of 1994 IEEE Region 10's Ninth Annual International Conference. Theme: Frontiers of Computer
Technology (Cat. No.94CH3417-3)
p. 10-14 vol.1
Editors: Chan, T.K.
Publisher: IEEE
New York, NY, USA
Date: 1994 2 vol. xxvii+1111 pp.
Country of Publication: USA
ISBN: 0 7803 1862 5
Language: English
Conf. Date: 22-26 Aug. 1994
Conf. Loc: Singapore
Conf. Sponsor: IEEE Region 10; Comput. Chapter, IEEE
Singapore Sect.; Inst. Eng., Singapore; IEEE
Comput. Soc
Treatment: Practical; Theoretical/Mathematical

Abstract: A distributed memory, message passing MIMD and a distributed networked implementation of the progressive refined (PR) radiosity method are presented in this paper. The latter adopts a multiple server-single client approach instead of the usual single server-multiple client model. 3D axis-aligned bounding boxes are used to speed up the visibility determination of ray traced form factors. Results from both implementations are presented and compared. Several proposals to further improve the performance and increase the efficiencies are suggested as well. (7 Refs.)
Classification: C6130B (Graphics techniques); C6150N (Distributed systems software); C5440 (Multiprocessing systems); C5220P (Parallel architecture)
Thesaurus: Brightness; Client-server systems; Distributed memory systems; Message passing; Ray tracing; Rendering [computer graphics] Free Terms: Distributed radiosity; Parallel radiosity; Distributed memory message passing MIMD; Distributed networked implementation; Progressive refined radiosity method; Multiple server-single client approach; Single server-multiple client model; 3D axis-aligned bounding boxes; Visibility determination; Ray traced form factors

95-21
Doc Type: Conference Paper
Title: Parallel radiosity approaches for mesh connected machines
Authors: Renaud, C.; Bricout, F.; Lepretre, E.
Affiliation: Lab. d'Informatique Fondamentale, Univ. des Sci. et Technol. de Lille, Villeneuve d'Ascq, France
Conf. Title: Parallel Computing: Trends and Applications. Proceedings of the International Conference ParCo93
p. 541-4
Editors: Joubert, G.R.; Peters, F.J.; Trystram, D.; Evans, D.J.
Publisher: Elsevier
Amsterdam, Netherlands
Date: 1994 xvi+728 pp.
Country of Publication: Netherlands
ISBN: 0 444 81841 3
Language: English
Conf. Date: 7-10 Sept. 1993
Conf. Loc: Grenoble, France
Conf. Sponsor: ARCHIPEL; CNRS; Elsevier Sci. Publishers;
IMAG; INPG; INRIA; et al
Treatment: Theoretical/Mathematical

Abstract: The radiosity method is one of the most powerful approaches that solves the global illumination problem in the case of perfectly diffuse environments. This algorithm requires the discretization of the objects into small planar surfaces, called patches. By shooting light from every patch sequentially, the light energy received by each patch is computed taking into account direct and indirect illumination. In order to do it, a geometric value, the form factor, must be processed, representing the part of the energy leaving a patch and reaching another one. Two main approaches are used to compute form factors: projective and ray casting methods. As this form factor is computationally demanding, we study the implementation and the performances of the two approaches onto the MP1 massively parallel machine. We present the radiosity algorithm and the two form factor computation approaches in section 2. Then, section 3 and 4 details our parallel implementation on the MP-1. Section 5 describes some results that have been obtained. (4 Refs.) Classification: C5260B (Computer vision and image processing techniques); C6130B (Graphics techniques)
Thesaurus: Image processing; Parallel algorithms
Free Terms: Mesh connected machines; Radiosity method; Global
illumination; Radiosity algorithm; Parallel implementation

95-22
Doc Type: Conference Paper
Title: Efficient parallel global illumination using density estimation
Authors: Zareski, D.; Wade, B.; Hubbard, P.; Shirley, P.
Affiliation: Program of Comput. Graphics, Cornell Univ., Ithaca, NY, USA
Conf. Title: 1995 Parallel Rendering Symposium (PRS 95) (IEEE Cat. No. 95TB8134)
p. 47-54, 104-5
Publisher: ACM
New York, NY, USA
Date: 1995 107 pp.
Country of Publication: USA
ISBN: 0 89791 774 1
CCC: 0 89791 774 1/95/10...$3.50
Language: English
Conf. Date: 30-31 Oct. 1995
Conf. Loc: Atlanta, GA, USA
Conf. Sponsor: IEEE Comput. Soc. Techn. Committee on
Comput. Graphics; ACM SIGGRAPH
Treatment: Theoretical/Mathematical

Abstract: The paper presents a multicomputer, parallel version of the recently-proposed 'density estimation' (DE) global illumination method, designed for computing solutions of environments with high geometric complexity (as many as hundreds of thousands of initial surfaces). In addition to the diffuse inter-reflections commonly handled by conventional radiosity methods, this new method can also handle energy transport involving arbitrary non-diffuse surfaces. Output can either be Gouraud-shaded elements for interactive walk-throughs, or ray-traced images for higher quality still frames.

The key difference of the DE algorithm from conventional radiosity, in terms of its ability to parallelize efficiently, is its microscopic view of energy transport, which avoids the O(n/sup 2/) pairwise surface interactions of most previous macroscopic radiosity algorithms (i.e., those without clustering). Parallel DE is implemented as two separate parallel programs which perform different phases of the DE method. The first program performs the particle-tracing phase, and the second performs the density-estimation and meshing phases. Each parallel program consists of a single master task and multiple worker tasks executing on separate workstations connected over a local area network. Communication is performed using the PVM software package and a shared file system. The goal of this effort is to provide a near-linear speedup for solutions to existing environment models using tens of processors. The parallel efficiency of the first program has been measured to be above 90% for as many as 16 workers, and the parallel efficiency of the second program has been measured to be above 70% for as many as 12 workers. (34 Refs.) Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6110P (Parallel programming); C6150N (Distributed systems software)
Thesaurus: Brightness; Density; Lighting; Local area networks; Parallel algorithms; Parallel programming; Ray tracing; Realistic images; Rendering [computer graphics]; Workstations
Free Terms: Efficient parallel global illumination; Density estimation; Multicomputer parallel density estimation global illumination method; High geometric complexity environments; Diffuse inter-reflections; Energy transport; Arbitrary nondiffuse surfaces; Gouraud-shaded elements; Interactive walk-throughs; Ray-traced images; Still frames; Radiosity; Parallelization; Parallel programs; Particle-tracing phase; Meshing phase; Master task; Multiple worker tasks; Workstations; Local area network; PVM software package; Shared file system

95-23
Doc Type: Conference Paper
Title: Load balancing for a parallel radiosity algorithm
Authors: Sturzlinger, W.; Schaufler, G.; Volkert, J.
Affiliation: GUP Univ., Linz, Austria
Conf. Title: 1995 Parallel Rendering Symposium (PRS 95) (IEEE Cat. No. 95TB8134)
p. 39-45
Publisher: ACM
New York, NY, USA
Date: 1995 107 pp.
Country of Publication: USA
ISBN: 0 89791 774 1
CCC: 0 89791 774 1/95/10...$3.50
Language: English
Conf. Date: 30-31 Oct. 1995
Conf. Loc: Atlanta, GA, USA
Conf. Sponsor: IEEE Comput. Soc. Techn. Committee on
Comput. Graphics; ACM SIGGRAPH
Treatment: Theoretical/Mathematical

Abstract: The radiosity method models the interaction of light between diffuse surfaces, thereby accurately predicting global illumination effects. Due to the high computational effort to calculate the transfer of light between surfaces and the memory requirements for the scene description, a distributed, parallelized version of the algorithm is needed for scenes consisting of thousands of surfaces. We present several load distribution schemes for such a parallel algorithm which includes progressive refinement and adaptive subdivision for fast solutions of high quality. The load is distributed before the calculations in a static way. During the computation the load is redistributed dynamically to make up for individual differences in processor loads. The dynamic load balancing scheme never generates more data packets than the original algorithm and avoids overloading processors through actions taken by the scheme. (26 Refs.)
Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6150N (Distributed systems software)
Thesaurus: Brightness; Lighting; Parallel algorithms; Parallel machines; Rendering [computer graphics]; Resource allocation; Timing Free Terms: Parallel radiosity algorithm; Light interaction; Diffuse surfaces; Global illumination effects; Computational effort; Light transfer; Memory requirements; Scene description; Distributed parallelized algorithm; Load balancing; Load distribution schemes; Progressive refinement; Adaptive subdivision; High quality solutions; Dynamic load redistribution; Processor loads; Data packets; Static load balancing

95-24
Doc Type: Conference Paper
Title: Implementation results and analysis of a parallel progressive radiosity
Authors: Guitton, P.; Roman, J.; Subrenat, G.
Affiliation: Lab. Bordelais de Recherche en Inf., Bordeaux I Univ., Talence, France
Conf. Title: 1995 Parallel Rendering Symposium (PRS 95) (IEEE Cat. No. 95TB8134)
p. 31-8, 101
Publisher: ACM
New York, NY, USA
Date: 1995 107 pp.
Country of Publication: USA
ISBN: 0 89791 774 1
CCC: 0 89791 774 1/95/10...$3.50
Language: English
Conf. Date: 30-31 Oct. 1995
Conf. Loc: Atlanta, GA, USA
Conf. Sponsor: IEEE Comput. Soc. Techn. Committee on
Comput. Graphics; ACM SIGGRAPH
Treatment: Theoretical/Mathematical

Abstract: The quality of synthetic images depends on the quality of the modelling of the three-dimensional scenes to be visualized; the more numerous the geometrical and optical details are, the more realistic are the resulting images. Unfortunately, such scene descriptions need a large amount of memory, as well as a long computation time. In order to deal with these restrictions, we propose a parallel implementation for an extended stochastic progressive radiosity method, where form factors are computed with a ray tracing scheme, on a network of processors with a distributed memory and a message passing mechanism. Our program has already treated very large scenes (more than one million patches for example). (29 Refs.)
Classification: C6130B (Graphics techniques); C6150N (Distributed systems software); C5220P (Parallel architecture); C4240P (Parallel programming and algorithm theory); C1140 (Probability and statistics) Thesaurus: Brightness; Data visualisation; Distributed memory systems; Message passing; Parallel algorithms; Parallel architectures; Ray tracing; Rendering [computer graphics]; Stochastic processes Free Terms: Parallel progressive radiosity; Synthetic image quality; Three-dimensional scene modelling quality; Visualization; Optical details; Geometrical details; Scene descriptions; Extended stochastic progressive radiosity method; Form factors; Ray tracing scheme; Processor network; Distributed memory; Message passing mechanism; Program

95-25
Doc Type: Conference Proceedings
Conf. Title: 1995 Parallel Rendering Symposium (PRS 95)
Publisher: ACM
New York, NY, USA
Date: 1995 107 pp.
Country of Publication: USA
ISBN: 0 89791 774 1
CCC: 95/10...$3.50
Language: English
Conf. Date: 30-31 Oct. 1995
Conf. Loc: Atlanta, GA, USA
Conf. Sponsor: IEEE Comput. Soc. Techn. Committee on
Comput. Graphics; ACM SIGGRAPH
Treatment: Practical

Abstract: The following topics were dealt with: volume rendering; parallel radiosity; surface rendering; and graphics hardware. Classification: C6130B (Graphics techniques); C5540 (Terminals and graphic displays); C5440 (Multiprocessing systems); C6110P (Parallel programming)
Thesaurus: Computer graphic equipment; Parallel machines; Parallel programming; Ray tracing; Rendering [computer graphics]; Special purpose computers
Free Terms: Parallel rendering; Volume rendering; Parallel radiosity; Surface rendering; Graphics hardware

95-26
Doc Type: Conference Paper
Title: An object parallel approach for radiosity on the MP-1
Authors: Renaud, C.; Bricout, F.; Lepretre, E.
Affiliation: Lab. d'Inf. Fondamentale de Lille, Univ. des Sci. et Tech. de Lille Flandres Artois, Villeneuve d'Ascq, France
Conf. Title: Massively Parallel Processing Applications and Development. Proceedings of the 1994 EUROSIM Conference
p. 887-94
Editors: Dekker, L.; Smit, W.; Zuidervaart, J.C.
Publisher: Elsevier
Amsterdam, Netherlands
Date: 1994 xxii+973 pp.
Country of Publication: Netherlands
ISBN: 0 444 81784 0
Language: English
Conf. Date: 21-23 June 1994
Conf. Loc: Delft, Netherlands
Conf. Sponsor: AKZO NOBEL; BSO; Convex Comput.; HPCN
projects; IBM; NOWESP; et al
Treatment: Practical

Abstract: Radiosity is a graphical method which provides high quality synthetic images by taking into account the use of diffuse reflections between surfaces. Unfortunately, this method is very time-consuming, because of the evaluation of geometric quantities known as form factors. Substantial improvement in the efficiency of this method has been obtained by implementing a specifically designed algorithm on a large mesh-connected machine. We present an object based parallel implementation of projective approaches used with the radiosity algorithm. We also detail specific communication problems encountered in implementing the algorithms on the DEC MP-1. (8 Refs.) Classification: C6130B (Graphics techniques); C6150N (Distributed systems software); C5440 (Multiprocessing systems)
Thesaurus: Brightness; Computer graphics; DEC computers; Object-oriented programming; Parallel algorithms; Parallel machines Free Terms: Object parallel approach; Radiosity; MP-1; High quality synthetic images; Graphical method; Reflections; Geometric quantities; Time-consuming; Form factors; Large mesh-connected machine; Parallel algorithm; Radiosity algorithm

95-27
Doc Type: Conference Paper
Title: Optimally combining sampling techniques for Monte Carlo rendering
Authors: Veach, E.; Guibas, L.J.
Affiliation: Dept. of Comput. Sci., Stanford Univ., CA, USA
Conf. Title: Computer Graphics Proceedings. SIGGRAPH 95
p. 419-28
Editors: Cook, R.
Publisher: ACM
New York, NY, USA
Date: 1995 518 pp.
Country of Publication: USA
ISBN: 0 89791 701 4
CCC: 0 89791 701 4/95/008.$3.50
Language: English
Conf. Date: 6-11 Aug. 1995
Conf. Loc: Los Angeles, CA, USA
Conf. Sponsor: ACM
Treatment: Practical; Theoretical/Mathematical

Abstract: Monte Carlo integration is a powerful technique for the evaluation of difficult integrals. Applications in rendering include distribution ray tracing, Monte Carlo path tracing, and form-factor computation for radiosity methods. In these cases variance can often be significantly reduced by drawing samples from several distributions, each designed to sample well some difficult aspect of the integrand. Normally this is done by explicitly partitioning the integration domain into regions that are sampled differently. We present a powerful alternative for constructing robust Monte Carlo estimators, by combining samples from several distributions in a way that is provably good. These estimators are unbiased, and can reduce variance significantly at little additional cost. We present experiments and measurements from several areas in rendering: calculation of glossy highlights from area light sources, the 'final gather' pass of some radiosity algorithms, and direct solution of the rendering equation using bidirectional path tracing. (14 Refs.) Classification: C6130B (Graphics techniques); C4260 (Computational geometry); C4160 (Numerical integration and differentiation); C1140G (Monte Carlo methods)
Thesaurus: Computational geometry; Integration; Monte Carlo methods; Ray tracing; Rendering [computer graphics]
Free Terms: 3D graphics; Fredholm equations; Sampling techniques; Monte Carlo rendering; Distribution ray tracing; Monte Carlo path tracing; Form-factor computation; Radiosity methods; Monte Carlo estimators; Glossy highlights

95-28
Doc Type: Conference Paper
Title: Feature-based control of visibility error: a multi-resolution clustering algorithm for global illumination
Authors: Sillion, F.; Drettakis, G.
Affiliation: CNRS, Grenoble, France
Conf. Title: Computer Graphics Proceedings. SIGGRAPH 95
p. 145-52
Editors: Cook, R.
Publisher: ACM
New York, NY, USA
Date: 1995 518 pp.
Country of Publication: USA
ISBN: 0 89791 701 4
CCC: 0 89791 701 4/95/008.$3.50
Language: English
Conf. Date: 6-11 Aug. 1995
Conf. Loc: Los Angeles, CA, USA
Conf. Sponsor: ACM
Treatment: Practical

Abstract: In this paper we introduce a new approach to controlling error in hierarchical clustering algorithms for radiosity. The new method ensures that just enough work is done to meet the user's quality criteria. To this end the importance of traditionally ignored visibility error is identified, and the concept of features is introduced as a way to evaluate the quality of an image. A methodology to evaluate error based on features is presented, which leads to the development of a multi-resolution visibility algorithm. An algorithm to construct a suitable hierarchy for clustering and multi-resolution visibility is also proposed. Results of the implementation show that the multi-resolution approach has the potential of providing significant computational savings depending on the choice of feature size the user is interested in. They also illustrate the relevance of the feature-based error analysis. The proposed algorithms are well suited to the development of interactive lighting simulation systems since they allow more user control. Two additional mechanisms to control the quality of a simulation are presented: The evaluation of internal visibility in a cluster produces more accurate solutions for a given error bound; a progressive multi-gridding approach is introduced for hierarchical radiosity, allowing continuous refinement of a solution in an interactive session. (19 Refs.)
Classification: C6130B (Graphics techniques)
Thesaurus: Brightness; Computer graphics; Error analysis; Image resolution; Lighting; Visibility
Free Terms: Visibility; Clustering algorithm; Global illumination; Clustering algorithms; Radiosity; Multi-resolution visibility

95-29
Doc Type: Conference Paper
Title: A parallel system for photo realistic artificial scene rendering
Authors: Deprettere, E.F.; Hekstra, G.H.; Li-Shen Sheng; Jichun
Bu; Boersma, G.
Affiliation: Dept. of Electr. Eng., Delft Univ. of Technol.,
Netherlands
Conf. Title: VLSI Signal Processing VII (Cat. No.94TH8008)
p. 425-38
Editors: Rabaey, J.; Chau, P.M.; Eldon, J.
Publisher: IEEE
New York, NY, USA
Date: 1994 xii+511 pp.
Country of Publication: USA
ISBN: 0 7803 2123 5
CCC: 0 7803 2123 5/94/$4.00
Language: English
Conf. Date: 26-28 Oct. 1994
Conf. Loc: La Jolla, CA, USA
Conf. Sponsor: IEEE Signal Process. Soc
Treatment: Application; Practical

Abstract: We present a parallel system for fast rendering of artificial scenes with photo realism. The underlying parallel algorithm is based on ray-tracing and radiosity shading. The system consists of a standard workstation, a medium-size mesh of cluster processors and a high-bandwidth interconnection between them. Each cluster processor consists of a programmable TMS320C40 core and three dedicated VLSI satellites. The rendering algorithm runs on both the workstation host and its rendering mate in a true shared/distributed manner. The system is the result of an exercise in combined algorithm and architecture design as well as software/hardware co-design. (6 Refs.)
Classification: C6130B (Graphics techniques); C6110P (Parallel programming); C5130 (Microprocessor chips); C5220P (Parallel architecture); C5540 (Terminals and graphic displays) Thesaurus: Brightness; Computer graphic equipment; Coprocessors; Data visualisation; Image texture; Parallel algorithms; Ray tracing; Realistic images; Rendering [computer graphics]; VLSI Free Terms: Photo realism; Parallel system; Artificial scene rendering; Parallel algorithm; Ray-tracing; Radiosity shading; Cluster processors; Programmable TMS320C40 core; Dedicated VLSI satellites; Workstation host; Software/hardware co-design

95-30
Doc Type: Journal Paper
Title: Modelling radiative properties of light sources and surfaces
Authors: Paul, J.C.; Deville, P.M.; Winkler, C.
Affiliation: CNRS, Nancy I Univ., France
Journal: Journal of Visualization and Computer Animation
Vol: 6 Iss: 4 p. 231-40
Date: Oct.-Dec. 1995
Country of Publication: UK
ISSN: 1049-8907 CODEN: JVCAEO
CCC: 1049-8907/95/040231-10
Language: English
Treatment: Practical

Abstract: The paper describes methods that can be used for modelling radiative properties of light sources and materials, in a radiosity computation algorithm. These methods have been designed in order to improve the photorealistic rendering of complex architectural scenes as well as to allow illumination engineering applications. They are based on the accurate modelling of the spatial and spectral emittance distributions of the light sources, and the surface reflectance/transmittance distributions from measurement, and allow the exact colorimetric properties of the light sources and the surfaces to be calculated. A method for changing radiosity inputs during the radiosity process, without recalculating the solution entirely is also proposed. This allows modifications in design or dynamic lighting effects to be simulated more interactively. (18 Refs.)
Classification: C6130B (Graphics techniques); C6185 (Simulation techniques)
Thesaurus: Brightness; Digital simulation; Light sources; Rendering [computer graphics]
Free Terms: Radiative properties; Light sources; Radiosity computation algorithm; Photorealistic rendering; Complex architectural scenes; Illumination engineering applications; Accurate modelling; Spectral emittance distributions; Surface reflectance/transmittance distributions; Exact colorimetric properties; Radiosity inputs; Dynamic lighting effects

95-31
Doc Type: Journal Paper
Title: A radiosity solution for random fractal surfaces
Authors: En-Hua Wu
Affiliation: Inst. of Comput. Technol., Acad. Sinica, Beijing, China Journal: Journal of Visualization and Computer Animation
Vol: 6 Iss: 4 p. 219-29
Date: Oct.-Dec. 1995
Country of Publication: UK
ISSN: 1049-8907 CODEN: JVCAEO
CCC: 1049-8907/95/040219-11
Language: English
Treatment: Practical

Abstract: Fractal geometry provides an outstanding mathematical tool for simulating natural phenomena. However, the recursive process of stochastic modeling in generating random fractals puts forward difficult problems in the rendering. At present, only some special ray tracing methods have been provided to render fractals, mainly producing specular illumination. The paper proposes a radiosity solution for rendering random fractals, in which diffuse interreflection can be calculated in the process of stochastic modelling. By this solution, the recursive process of fractal generation is naturally incorporated into the progressive refinement procedure of the radiosity solution. Particularly, it becomes possible for fractal surfaces to participate in the energy shooting process of the radiosity solution. The key problem in the proposed approach is in calculating the radiosity redistribution for fractal subdivision. An algorithm for solving the problem has been proposed and implemented. Test examples show that the method is quite efficient. The technique may improve the visual realism of the radiosity image and promote the practical value of the radiosity solution. (26 Refs.)
Classification: C6130B (Graphics techniques); C4260 (Computational geometry); C1160 (Combinatorial mathematics)
Thesaurus: Brightness; Computational geometry; Fractals; Ray tracing; Rendering [computer graphics]
Free Terms: Radiosity solution; Random fractal surfaces; Fractal geometry; Natural phenomena; Stochastic modeling; Random fractals; Ray tracing methods; Specular illumination; Diffuse interreflection; Stochastic modelling; Recursive process; Progressive refinement procedure; Energy shooting process; Radiosity redistribution; Fractal subdivision; Visual realism

95-32
Doc Type: Conference Paper
Title: Distributed tree structures for N-body simulation
Authors: Pai, A.S.; Young-Il Choo; Chen, M.
Affiliation: Dept. of Comput. Sci., Yale Univ., New Haven, CT, USA Conf. Title: Languages, Compilers and Run-Time Systems for Scalable Computers
p. 307-10
Editors: Szymanski, B.K.; Sinharoy, B.
Publisher: Kluwer Academic Publishers
Norwell, MA, USA
Date: 1996 xiv+335 pp.
Country of Publication: USA
ISBN: 0 7923 9635 9
Language: English
Conf. Date: 22-24 May 1995
Conf. Loc: Troy, NY, USA
Treatment: Practical

Abstract: Several particle simulation algorithms, such as the Barnes-Hut and the Fast Multipole method, proceed by hierarchically decomposing the simulation space and representing the distribution of the simulated particles in an adaptive tree data structure which varies as the simulation proceeds. Such tree structures are also used in radiosity calculation, computational fluid mechanics, and other applications. Managing such a structure on a distributed memory machine poses significant difficulties in terms of communication costs and partitioning strategies. We present the design and an object oriented implementation of a Virtual Distributed Tree (VDT) structure that provides a high level view of a dynamic and irregular tree data structure to the application developer while hiding the low level communication and tree management functions that are implemented using a message passing system below the class interface. The application interface provides various methods to manipulate the tree in a global fashion while the run time system handles most of the other details of parallel execution, including the partition of the data structure across several processors, communication, and load balancing. Our emphasis is on programmability and ease of use: we want an easily comprehensible framework so that various applications that require adaptive trees can be coded up quickly. (6 Refs.) Classification: C7320 (Physics and chemistry computing); C6185 (Simulation techniques); C6120 (File organisation); C6110J (Object-oriented programming); C6150N (Distributed systems software) Thesaurus: Digital simulation; Message passing; N-body problems; Object-oriented programming; Physics computing; Tree data structures Free Terms: Distributed tree structures; N-body simulation; Particle simulation algorithms; Adaptive tree data structure; Distributed memory machine; Object oriented implementation; Virtual Distributed Tree structure; High level view; Irregular tree data structure; Application developer; Low level communication; Tree management functions; Message passing system; Run time system; And load balancing; Programmability; Adaptive trees

95-33
Doc Type: Conference Paper
Title: Discontinuity meshing and hierarchical multi-wavelet radiosity
Authors: Bouatouch, K.; Pattanaik, S.N.
Affiliation: IRISA, Rennes, France
Conf. Title: Proceedings Graphics Interface '95
p. 109-15
Editors: Davis, W.A.; Prusinkiewicz, P.
Publisher: Canadian Inf. Process. Soc
Toronto, Ont., Canada
Date: 1995 viii+281 pp.
Country of Publication: Canada
ISBN: 0 9695338 4 5
Language: English
Conf. Date: 17-19 May 1995
Conf. Loc: Quebec, Que., Canada
Treatment: Practical; Theoretical/Mathematical

Abstract: Proposes an extension to the work of Lischinski et al. (1993) on combining the hierarchical radiosity method and discontinuity meshing. The proposed extension supports a higher-order radiosity function at the estimation step itself. We have carried out this extension using multi-wavelet basis functions. Unlike the multi-wavelet radiosity work of Gortler et al. (1993), which uses regular quadtree subdivision, we carry out the subdivision along the discontinuity boundary. In other words, instead of deriving the finer basis functions by uniform parametric dilations of a mother basis function, we derive the finer basis by mapping the mother basis to arbitrary subdomains created during the subdivision along the discontinuity boundary. To carry out push and pull operations, which are crucial to the hierarchical algorithm, we compute the necessary filter functions. Our method combines the advantages of wavelet radiosity and discontinuity meshing. The preliminary results show significant computational improvements. (6 Refs.)
Classification: C6130B (Graphics techniques); C4190 (Other numerical methods)
Thesaurus: Brightness; Computer graphics; Wavelet transforms Free Terms: Discontinuity meshing; Hierarchical multi-wavelet radiosity; Higher-order radiosity function; Estimation step; Multi-wavelet basis functions; Subdivision; Discontinuity boundary; Arbitrary subdomains; Push operations; Pull operations; Hierarchical algorithm; Filter functions; Computational improvements

95-34
Doc Type: Conference Paper
Title: Massively parallel radiosity in the presence of multiple isotropic volume scattering
Authors: Langer, M.S.; Breton, P.; Zucker, S.W.
Affiliation: Center for Intelligent Machines, McGill Univ., Montreal, Que., Canada
Conf. Title: Proceedings Graphics Interface '95
p. 103-8
Editors: Davis, W.A.; Prusinkiewicz, P.
Publisher: Canadian Inf. Process. Soc
Toronto, Ont., Canada
Date: 1995 viii+281 pp.
Country of Publication: Canada
ISBN: 0 9695338 4 5
Language: English
Conf. Date: 17-19 May 1995
Conf. Loc: Quebec, Que., Canada
Treatment: Practical

Abstract: Presents a massively parallel algorithm for computing radiosity in a scene containing an isotropic scattering medium of high albedo. The algorithm is based on a new formalism: a coordinate evolution on the set of light rays in the scene. The evolution reparameterizes rays from their points of origin to their points of termination. Local coordinate systems on the set of light rays are distributed over a two-dimensional lattice of parallel processors, and transformations between coordinate systems are computed using only local communication between processors. The algorithm is implemented on a MasPar-1 which is a SIMD computer having over 2000 processors. (19 Refs.)
Classification: C6130B (Graphics techniques); C6110P (Parallel programming)
Thesaurus: Albedo; Brightness; Computer graphics; Light scattering; Parallel algorithms; Ray tracing
Free Terms: Massively parallel algorithm; Radiosity computation; Multiple isotropic volume scattering; High-albedo isotropic scattering medium; Coordinate evolution; Light ray
reparameterization; Local coordinate systems; 2D parallel processor lattice; MasPar-1; SIMD computer; Scene

95-35
Doc Type: Conference Paper
Title: Constructing partitioning trees from Bezier-curves for efficient intersections and visibility
Authors: Naylor, B.; Rogers, L.
Affiliation: AT&T Bell Labs., Murray Hill, NJ, USA
Conf. Title: Proceedings Graphics Interface '95
p. 44-55
Editors: Davis, W.A.; Prusinkiewicz, P.
Publisher: Canadian Inf. Process. Soc
Toronto, Ont., Canada
Date: 1995 viii+281 pp.
Country of Publication: Canada
ISBN: 0 9695338 4 5
Language: English
Conf. Date: 17-19 May 1995
Conf. Loc: Quebec, Que., Canada
Treatment: Theoretical/Mathematical

Abstract: While a very effective method for designing objects is to describe their surfaces using non-linear parametric representations, these are not necessarily the best for executing all of the computations required for modeling and rendering. These computations include set operations for CSG, collision detection, ray-surface intersections, visible surface determination, shadow calculations, radiosity transfer, and view-volume clipping, all of which involve computing intersections, possibly in visibility order. Intersections are intrinsically easier to compute using the implicit rather than the parametric form; however, implicitizing parametric surfaces can produce polynomials of too high a degree. An alternative that we introduce is to convert the non-linear parametric form into a piecewise-linear, multi-resolution, implicit form, viz. the binary space partitioning tree. This provides a hierarchical organization of the many linear pieces, resulting in acceleration of intersection and visibility calculations. We describe how to construct such a tree representation of a region of 2-space whose boundary is a piecewise-Bezier curve of any degree. We then describe how this construction can be used in 3-space to build trees representing generalized cylinders. This provides a very effective method for constructing multi-resolution trees that are 'good', as measured by expected cost, for intersections and visibility. (18 Refs.) Classification: C4260 (Computational geometry); C1160 (Combinatorial mathematics); C6130B (Graphics techniques)
Thesaurus: Computational geometry; Computer graphics; Curve fitting; Trees [mathematics]
Free Terms: Partitioning tree construction; Bezier curves; Visibility; Intersections; Nonlinear parametric representation; Rendering; Modeling; Parametric surfaces; Polynomials; Piecewise-linear multiresolution; Binary space partitioning tree; Hierarchical organization; Tree representation; Piecewise-Bezier curve; Generalized cylinders; Cost

95-36
Doc Type: Journal Paper
Title: A unified hierarchical algorithm for global illumination with scattering volumes and object clusters
Authors: Sillion, F.X.
Journal: IEEE Transactions on Visualization and Computer Graphics
Vol: 1 Iss: 3 p. 240-54
Date: Sept. 1995
Country of Publication: USA
ISSN: 1077-2626 CODEN: ITVGEA
CCC: 1077-2626/95/$04.00
Language: English
Treatment: Practical

Abstract: The paper presents a new radiosity algorithm that allows the simultaneous computation of energy exchanges between surface elements, scattering volume distributions, and groups of surfaces, or object clusters. The new technique is based on a hierarchical formulation of the zonal method, and efficiently integrates volumes and surfaces. In particular no initial linking stage is needed, even for inhomogeneous volumes, thanks to the construction of a global spatial hierarchy. An analogy between object clusters and scattering volumes results in a powerful clustering radiosity algorithm, with no initial linking between surfaces and fast computation of average visibility information through a cluster. We show that the accurate distribution of the energy emitted or received at the cluster level can produce even better results than isotropic clustering at a marginal cost. The resulting algorithm is fast and, more importantly, truly progressive as it allows the quick calculation of approximate solutions with a smooth convergence towards very accurate simulations. (37 Refs.)
Classification: C6130B (Graphics techniques); C6185 (Simulation techniques)
Thesaurus: Brightness; Digital simulation; Lighting; Realistic images Free Terms: Unified hierarchical algorithm; Global illumination; Scattering volumes; Object clusters; Radiosity algorithm; Simultaneous computation; Energy exchanges; Surface elements; Scattering volume distributions; Hierarchical formulation; Zonal method; Inhomogeneous volumes; Global spatial hierarchy; Clustering radiosity algorithm; Average visibility information; Approximate solutions; Smooth convergence; Accurate simulations; Lighting simulation; Realistic image synthesis

95-37
Doc Type: Conference Paper in Journal
Title: Using procedural RenderMan shaders for global illumination
Authors: Slusallek, P.; Pflaum, T.; Seidel, H.-P.
Affiliation: Graphische Datenverarbeitung, Erlangen-Nurnberg Univ., Germany
Journal: Computer Graphics Forum
Vol: 14 Iss: 3 p. C/311-24
Date: 1995
Country of Publication: UK
ISSN: 0167-7055 CODEN: CGFODY
Language: English
Conf. Title: EUROGRAPHICS '95
Conf. Date: 18 Aug.-1 Sept. 1995
Conf. Loc: Maastricht, Netherlands
Treatment: Practical

Abstract: 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. 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 put 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. (24 Refs.)
Classification: C6130B (Graphics techniques); C6180 (User interfaces) Thesaurus: Brightness; Lighting; Rendering [computer graphics]; User interfaces
Free Terms: Procedural RenderMan shaders; Global illumination; Radiosity; Monte Carlo ray tracing; Rendering systems; Interface format; Physically based scene description; RenderMan interface; Advanced global illumination techniques; Procedural descriptions; Reflection; Emission; Physically based rendering system

95-38
Doc Type: Conference Paper in Journal
Title: A new radiosity approach for regular objects: application to ruled surfaces
Authors: Arques, D.; Michelin, S.
Affiliation: Inst. Gaspard Monge, Univ. Marne-la-Vallee,
Noisy-le-Grand, France
Journal: Computer Graphics Forum
Vol: 14 Iss: 3 p. C/299-310
Date: 1995
Country of Publication: UK
ISSN: 0167-7055 CODEN: CGFODY
Language: English
Conf. Title: EUROGRAPHICS '95
Conf. Date: 18 Aug.-1 Sept. 1995
Conf. Loc: Maastricht, Netherlands
Treatment: Practical

Abstract: The 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 also show that the mathematical relation we have obtained: is especially efficient with ruled surfaces; significantly decreases the computation time; is well adapted to refinement or subdivision techniques and gives us an interesting variety of success. Calculation times are equivalent to those obtained with a projective method (hemi cube for example) but with an efficient control of the generated errors. (38 Refs.) Classification: C6130B (Graphics techniques); C4260 (Computational geometry)
Thesaurus: Brightness; Computational geometry; Computer graphics Free Terms: Radiosity approach; Regular objects; Ruled surfaces; Radiosity method; Form factor computation; Model properties; Surface meshing; Neighboring patches; Mathematical relation; Subdivision techniques; Projective method; Computer graphics; Ray tracing

95-39
Doc Type: Conference Paper in Journal
Title: Multiresolution B-spline radiosity
Authors: Yizhou Yut; Qunsheng Peng
Affiliation: State Key Lab. of CAD & CG, Zhejiang Univ., Hangzhou, China
Journal: Computer Graphics Forum
Vol: 14 Iss: 3 p. C/285-98
Date: 1995
Country of Publication: UK
ISSN: 0167-7055 CODEN: CGFODY
Language: English
Conf. Title: EUROGRAPHICS '95
Conf. Date: 18 Aug.-1 Sept. 1995
Conf. Loc: Maastricht, Netherlands
Treatment: Practical

Abstract: The 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. (18 Refs.) Classification: C6130B (Graphics techniques); C1160 (Combinatorial mathematics); C4160 (Numerical integration and differentiation); C4130 (Interpolation and function approximation); C4190 (Other numerical methods)
Thesaurus: Brightness; Extrapolation; Integration; Octrees; Rendering [computer graphics]; Splines [mathematics]; Wavelet transforms Free Terms: Multiresolution B spline radiosity; Wavelet radiosity method; Multiresolution B-spline radiosity; Radiosity distribution functions; Function extrapolation; Adaptive quadrature; Scale adjustmen; Octree; Hierarchical structures; Radiosity distribution; Element boundaries

95-40
Doc Type: Journal Paper
Title: Global illumination of random fractal surfaces by radiosity solution
Authors: Wu Enhua
Affiliation: Inst. of Software, Acad. Sinica, Beijing, China
Journal: Chinese Journal of Computers
Vol: 18 Iss: 5 p. 321-9
Date: May 1995
Country of Publication: China
ISSN: 0254-4164 CODEN: JIXUDT
Language: Chinese
Treatment: Practical; Theoretical/Mathematical

Abstract: Proposes a radiosity solution for rendering random fractals, in which diffuse interreflection can be calculated in the process of stochastic modelling. By this solution, the recursive process of fractal generation is naturally incorporated into the progressive refinement procedure for the radiosity solution. Particularly, it becomes possible for fractal surfaces to participate in the energy shooting process of the radiosity solution. The key problem in the proposed approach is in calculating the radiosity redistribution for fractal subdivision. An algorithm for solving the problem has been proposed and implemented. Test examples show that the method is quite efficient. The technique may improve the visual realism of the radiosity image and promote the practical value of the radiosity solution. (30 Refs.)
Classification: A4220G (Optical scattering, diffraction, dispersion and polarization in inhomogeneous media); A4220C (Wave fronts, ray tracing and beam spread in inhomogeneous media); A0555 (Fractals); C6130B (Graphics techniques); C4260 (Computational geometry); C1140Z (Other topics in statistics)
Thesaurus: Brightness; Computational geometry; Fractals; Lighting; Rendering [computer graphics]; Stochastic processes Free Terms: Global illumination; Random fractal surfaces; Radiosity solution; Rendering; Diffuse interreflection; Stochastic modelling; Recursive process; Fractal generation; Progressive refinement procedure; Energy shooting process; Radiosity redistribution; Fractal subdivision; Visual realism; Fractal geometry

95-41
Doc Type: Conference Paper
Title: Multithreaded processor for image generation
Authors: Sagishima, T.; Kimura, K.; Hirata, H.; Kiyohara, T.;
Asahara, S.; Onoye, T.; Shirakawa, I.
Affiliation: Audio Video Inf. Technol. Lab., Matsushita Electr. Ind. Co. Ltd., Kadoma, Japan
Conf. Title: 1994 IEEE International Symposium on Circuits and Systems (Cat. No.94CH3435-5)
p. 231-4 vol.4
Publisher: IEEE
New York, NY, USA
Date: 1994 6 vol. (494+644+300+366+794+510 pp.)
Country of Publication: USA
ISBN: 0 7803 1915 X
Language: English
Conf. Date: 30 May-2 June 1994
Conf. Loc: London, UK

Treatment: Application; Practical

Abstract: Multiple instruction execution is a major approach to designing high-performance processors. Superscalar and VLIW processor that utilize instruction level parallelism are usually focused on. On the other hand, the multithreaded processor can be expected to achieve a high degree of multiple instruction execution by utilizing coarse grain parallelism. Many computer graphics applications (such as the radiosity method and ray-tracing method) can be optimized by reorganizing the code to take advantage of coarse grain parallelism, but the degree of instruction level parallelism is not sufficient for a superscalar processor. Experimental result using the radiosity method shows that the 4-thread multithreaded processor achieves 2.9 times speedup over single thread, while the 4-issue superscalar processor manages around 1.5 times. By duplicating two kinds of function units, the performance of a multithreaded processor increases to 3.7 times, but the performance of a superscalar processor is saturated at around 1.5 times. Therefore, for computer graphics applications, the multithreaded processor is a better approach than the superscalar processor. (8 Refs.)
Classification: C5540 (Terminals and graphic displays); C6130B (Graphics techniques); C5220P (Parallel architecture); C5470 (Performance evaluation and testing); C5440 (Multiprocessing systems) Thesaurus: Computer graphic equipment; Computer graphics; Multiprocessing systems; Parallel architectures; Performance evaluation
Free Terms: Multithreaded processor; Image generation; Coarse grain parallelism; Computer graphics; Radiosity method

95-42
Doc Type: Conference Paper
Title: A massively parallel processing approach to fast photo-realistic image synthesis
Authors: Kobayashi, H.; Nakamura, T.
Affiliation: Fac. of Eng., Tohoku Univ., Sendai, Japan
Conf. Title: Communicating with Virtual Worlds
p. 497-507
Editors: Thalmann, N.M.; Thalmann, D.
Publisher: Springer-Verlag
Tokyo, Japan
Date: 1993 ix+613 pp.
Country of Publication: Japan
ISBN: 4 431 70125 7
Language: English
Conf. Date: 21-25 June 1993
Conf. Loc: Lausanne, Switzerland
Treatment: Practical

Abstract: Photo-realistic image synthesis based on the global illumination models is very time consuming and is not practical in the industrial world. This paper presents a new parallel processing scheme to accelerate photo-realistic image synthesis. A massively parallel processing system and its control scheme for this purpose are discussed. System behavior is also examined by using the queueing network model. (8 Refs.)
Classification: C6130B (Graphics techniques); C5440 (Multiprocessing systems); C6150N (Distributed systems software)
Thesaurus: Brightness; Lighting; Parallel processing; Performance evaluation; Queueing theory; Ray tracing; Realistic images Free Terms: Massively parallel processing; Fast photo-realistic image synthesis; Global illumination models; Time consuming; Control scheme; System behavior; Queueing network model; Radiosity; Ray tracing

95-43
Doc Type: Conference Paper
Title: Parallel processing in radiosity calculations
Authors: Lamotte, W.; Van Reeth, F.; Vandeurzen, L.; Flerackers,
E.
Affiliation: Appl. Comput. Sci. Lab., Limburgs Univ. Centrum, Diepenbeek, Belgium
Conf. Title: Communicating with Virtual Worlds
p. 485-96
Editors: Thalmann, N.M.; Thalmann, D.
Publisher: Springer-Verlag
Tokyo, Japan
Date: 1993 ix+613 pp.
Country of Publication: Japan
ISBN: 4 431 70125 7
Language: English
Conf. Date: 21-25 June 1993
Conf. Loc: Lausanne, Switzerland
Treatment: Practical; Theoretical/Mathematical

Abstract: Global illumination models have received a considerable amount of attention in realistic image synthesis research. Especially radiosity methods for realizing the illumination in scenes exhibiting global Lambertian diffuse reflection have been reported. Since the introduction of the progressive refinement methodology, the performance of the early pioneering algorithms has been improved drastically. In this paper, we go a step further in improving the performance by utilizing parallel processing techniques. Concretely, we elucidate a transputer based approach for realizing a parallel ray tracing based progressive radiosity method. (26 Refs.) Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6150N (Distributed systems software)
Thesaurus: Brightness; Lighting; Parallel algorithms; Performance evaluation; Ray tracing; Realistic images; Transputer systems Free Terms: Parallel processing; Radiosity calculations; Global illumination models; Realistic image synthesis; Global Lambertian diffuse reflection; Progressive refinement methodology; Transputer based approach; Parallel ray tracing; Progressive radiosity method

95-44
Doc Type: Conference Paper
Title: Solving the radiosity linear system
Authors: Gortler, S.J.; Cohen, M.F.
Affiliation: Dept. of Comput. Sci., Princeton Univ., NJ, USA
Conf. Title: Communicating with Virtual Worlds
p. 78-88
Editors: Thalmann, N.M.; Thalmann, D.
Publisher: Springer-Verlag
Tokyo, Japan
Date: 1993 ix+613 pp.
Country of Publication: Japan
ISBN: 4 431 70125 7
Language: English
Conf. Date: 21-25 June 1993
Conf. Loc: Lausanne, Switzerland
Treatment: Theoretical/Mathematical

Abstract: This paper discusses the various algorithms that have been proposed to solve the linear system arising in the radiosity method for image synthesis. These algorithms are placed within the context of the numerical methods literature. In particular, we show that the progressive radiosity method is equivalent to Southwell iteration, and the hierarchical method can be viewed as a preconditioning method that produces an approximately equivalent sparse system. When integrated with a heuristic predictor of where the significant entries in the sparse system will be, the result is the efficiencies claimed by the hierarchical methods. The goal in reexamining the radiosity methods is to extend the understanding of current algorithms in the effort of investigating new, more accurate, and efficient techniques. (19 Refs.)
Classification: C4140 (Linear algebra); C4130 (Interpolation and function approximation); C6130B (Graphics techniques) Thesaurus: Brightness; Iterative methods; Linear algebra; Realistic images
Free Terms: Radiosity linear system solving; Image synthesis; Numerical methods; Progressive radiosity method; Southwell iteration; Hierarchical method; Preconditioning method; Approximately equivalent sparse system; Heuristic predictor; Realistic images

95-45
Doc Type: Journal Paper
Title: Monte Carlo radiosity
Authors: Neumann, L.
Journal: Computing
Vol: 55 Iss: 1 p. 23-42
Date: 1995
Country of Publication: Austria
ISSN: 0010-485X CODEN: CMPTA2
CCC: 0010-485X/95/$1.00+0.20
Language: English
Treatment: Theoretical/Mathematical

Abstract: The fast radiosity-type methods for very complex diffuse environments, introduced in this paper, present a nearly linear-time solution. The outlined procedures rely on recursive algorithms with stochastic convergence for solving the radiosity equation system. Approximations of gathering and shooting at very low computational cost-rather than the exact matrix of a single reflection-are used. The efficiency of the methods is increased by applying variance reduction techniques. (18 Refs.)
Classification: A4220C (Wave fronts, ray tracing and beam spread in inhomogeneous media); A0260 (Numerical approximation and analysis); A0250 (Probability theory, stochastic processes, and statistics); C6130B (Graphics techniques); C1140G (Monte Carlo methods); C4130 (Interpolation and function approximation)
Thesaurus: Approximation theory; Brightness; Convergence of numerical methods; Geometrical optics; Monte Carlo methods; Rendering [computer graphics]; Stochastic processes
Free Terms: Monte Carlo method; Fast radiosity-type methods; Complex diffuse environments; Nearly linear-time solution; Recursive algorithms; Stochastic convergence; Radiosity equation system; Gathering approximation; Shooting approximation; Low computational cost; Efficiency; Variance reduction techniques; Transillumination method; Stochastic shooting method

95-46
Doc Type: Journal Paper
Title: Adjoint equations and random walks for illumination computation
Authors: Pattanaik, S.N.; Mudur, S.P.
Affiliation: Graphics & CAD Div., Nat. Centre for Software Technol., Bombay, India
Journal: ACM Transactions on Graphics
Vol: 14 Iss: 1 p. 77-102
Date: Jan. 1995
Country of Publication: USA
ISSN: 0730-0301 CODEN: ATGRDF
CCC: 0730-0301/95/0100-0077$03.50
Language: English
Treatment: Theoretical/Mathematical

Abstract: Introduces the potential equation that, along with the rendering equation, forms an adjoint system of equations and provides a mathematical framework for all known approaches to illumination computation based on geometric optics. The potential equation is more natural for illumination computations that simulate light propagation starting from the light sources, such as progressive radiosity and particle tracing. Using the mathematical handles provided by this framework and the random-walk solution model, we present a number of importance sampling schemes for improving the computation of flux estimation. Of particular significance is the use of approximately computed potential for directing a majority of the random walks through regions of importance in the environment, thus reducing the variance in the estimates of luminous flux in these regions. Finally, results from a simple implementation are presented to demonstrate the high-efficiency improvements made possible by the use of these techniques. (21 Refs.)
Classification: A4210D (Wave-front and ray tracing in homogeneous media); A0250 (Probability theory, stochastic processes, and statistics); C6130B (Graphics techniques); C1140G (Monte Carlo methods); C4260 (Computational geometry)
Thesaurus: Brightness; Equations; Geometrical optics; Light propagation; Light sources; Lighting; Monte Carlo methods; Random processes; Rendering [computer graphics]
Free Terms: Adjoint equations; Random walks; Illumination computation; Illumination potential equation; Rendering equation; Geometric optics; Light propagation; Light sources; Progressive radiosity; Particle tracing; Importance sampling schemes; Luminous flux estimation; Approximately computed potential; Variance reduction; High-efficiency improvements; Forward simulation; Global illumination; Monte Carlo simulation; Path tracing

95-47
Doc Type: Conference Paper
Title: A parallel radiosity system for large data sets
Authors: Stuttard, D.; Worrall, A.; Paddon, D.; Willis, C.
Affiliation: Dept. of Comput. Sci., Bristol Univ., UK Conf. Title: WSCG'95 (Winter School of Computer Graphics and Visualisation 95). Third International Conference in
Central Europe on Computer Graphics and Visualisation 95.
Conference Proceedings
p. 421-30 vol.2
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 186 8
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdia; Hewlett Packard
Treatment: Practical

Abstract: The radiosity method gives realistic results for synthesising images based on diffuse light interaction; however, the method is also very computationally expensive. We present a system for parallelising a progressive refinement radiosity method using a ray casting approach. The system decomposes the environment into two distinct entities: the model geometry and the radiosity sample points. These are then distributed amongst the processors, and message-passing communication protocols and caching methods are introduced to enable the system to cope with very large models whilst maintaining a high processing rate. (15 Refs.)
Classification: C6130B (Graphics techniques); C4260 (Computational geometry); C4240P (Parallel programming and algorithm theory); C6110P (Parallel programming); C5640 (Protocols); C6150N (Distributed systems software)
Thesaurus: Brightness; Cache storage; Computational geometry; Message passing; Parallel algorithms; Protocols; Ray tracing; Realistic images
Free Terms: Parallel radiosity system; Large data sets; Image synthesis; Diffuse light interaction; Parallelization; Progressive refinement radiosity method; Ray casting; Model geometry; Radiosity sample points; Distributed processing; Message-passing communication protocols; Caching methods; Processing rate

95-48
Doc Type: Conference Paper
Title: On convergence and complexity of radiosity algorithms
Authors: Szirmay-Kalos, L.; Marton, G.
Affiliation: Dept. of Process Control, Tech. Univ. Budapest, Hungary Conf. Title: WSCG'95 (Winter School of Computer Graphics and Visualisation 95). Third International Conference in
Central Europe on Computer Graphics and Visualisation 95.
Conference Proceedings
p. 313-22 vol.2
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 186 8
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdia; Hewlett Packard
Treatment: Theoretical/Mathematical

Abstract: This paper evaluates and compares the convergence and complexity characteristics of radiosity algorithms with a special emphasis on randomized methods. (4 Refs.)
Classification: C4260 (Computational geometry); C4240C (Computational complexity); C6130B (Graphics techniques)
Thesaurus: Brightness; Computational complexity; Computational
geometry; Computer graphics; Convergence of numerical methods; Randomised algorithms
Free Terms: Radiosity algorithms; Convergence; Complexity; Randomized methods; Finite element method; Computer graphics

95-49
Doc Type: Conference Paper
Title: Speeding up progressive radiosity by overshooting
Authors: Feda, M.
Affiliation: Inst. of Comput. Graphics, Tech. Univ. Wien, Austria Conf. Title: WSCG 95 (Winter School of Computer Graphics and Visualisation 95). Third International Conference in
Central Europe on Computer Graphics and Visualisation 95
p. 87-92 vol.1
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdis; Hewlett Packard; Intergraph
CR; et al
Treatment: Theoretical/Mathematical

Abstract: Overshooting techniques have proven to significantly speed up the convergence of radiosity computation. Similar methods (overrelaxation) have also been widely used in numerical mathematics to speed up iterative solution methods for linear equation systems, e.g. Gauss-Seidel iteration. This paper gives a comprehensive description of all overshooting techniques. Advantages and disadvantages of the different techniques are also described. (7 Refs.)
Classification: C4260 (Computational geometry); C4130 (Interpolation and function approximation); C6130B (Graphics techniques) Thesaurus: Brightness; Computational geometry; Computer graphics; Convergence of numerical methods; Iterative methods; Relaxation theory
Free Terms: Progressive radiosity; Overshooting; Convergence; Radiosity computation; Overrelaxation; Numerical mathematics; Iterative solution methods; Linear equation systems; Gauss-Seidel iteration

95-50
Doc Type: Conference Paper
Title: Dynamic subdivision in radiosity
Authors: Dubuis, E.; Bieri, H.
Affiliation: Inst. fur Inf. und Angewandte Math., Bern Univ.,
Switzerland
Conf. Title: WSCG 95 (Winter School of Computer Graphics and
Visualisation 95). Third International Conference in
Central Europe on Computer Graphics and Visualisation 95
p. 79-86 vol.1
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdis; Hewlett Packard; Intergraph
CR; et al
Treatment: Practical; Theoretical/Mathematical

Abstract: This paper presents a fast radiosity algorithm for illuminating scenes containing large piecewise polygonal surfaces. Dynamic subdivision is based on the well known adaptive subdivision, introduced by (Cohen et al., 1986). During the illumination process, patches in areas with high intensity gradients are refined. Contrary to adaptive subdivision, the presented algorithm subdivides patches not in a static way. The patch hierarchy is dynamic and adapted to the respective state of the illumination process. To take a decision concerning patch subdivision, more information about the gathered energy of a patch is considered then with adaptive subdivision. The results show that this new algorithm can lead to remarkable speedups compared to adaptive subdivision. (8 Refs.)
Classification: C6130B (Graphics techniques); C4260 (Computational geometry)
Thesaurus: Brightness; Computational geometry; Lighting; Realistic images
Free Terms: Fast radiosity algorithm; Scene illumination; Large piecewise polygonal surfaces; Adaptive subdivision; Dynamic subdivision; Illumination process; High intensity gradients; Patch hierarchy; Patch subdivision

95-51
Doc Type: Conference Paper
Title: A parallel approach to hierarchical radiosity
Authors: Bohn, C.-A.; Garmann, R.
Affiliation: German Nat. Res. Center for Comput. Sci., St. Augustin, Germany
Conf. Title: WSCG 95 (Winter School of Computer Graphics and
Visualisation 95). Third International Conference in
Central Europe on Computer Graphics and Visualisation 95
p. 26-35 vol.1
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdis; Hewlett Packard; Intergraph
CR; et al
Treatment: Practical; Theoretical/Mathematical

Abstract: A parallel algorithm solving the radiosity equation is presented. It is based on the hierarchical approach (HR) (Hanrahan et al., 1991) and realized on a massively parallel supercomputer-the Connection-Machine 5. Our algorithm considers the HR approach as a process that manipulates a huge graph structure. Simulated annealing is used in the graph's rearranging procedure to achieve a good work-balance and nearly optimal communication costs. The implementation shows a significant step to facilitate the application of a radiosity solver, produced on one hand by the user-support that HR needs, on the other hand by the fast calculation times the parallel implementation offers. On 64 processors we obtained a speed-up of 8.4. (13 Refs.)
Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C5440 (Multiprocessing systems); C6150N (Distributed systems software)
Thesaurus: Brightness; Data visualisation; Parallel algorithms; Parallel machines; Simulated annealing
Free Terms: Parallel algorithm; Hierarchical radiosity; Computer graphics; Radiosity equation solving; Message passing; Hierarchical approach; Massively parallel supercomputer; Connection-Machine 5; Graph structure; Simulated annealing; Optimal communication costs; Radiosity solver; Fast calculation times; Scientific visualization; Rendering

95-52
Doc Type: Conference Proceedings
Conf. Title: Proceedings of Third International Conference in Central Europe on Computer Graphics and Visualisation: Winter
School of Computer Graphics
Editors: Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1995 2 vol. 485 pp.
Country of Publication: Czech Republic
Availability: Union Agency, Na Mazinach 9, 322 00 Plzen, Czech Republic Language: English
Conf. Date: 14-18 Feb. 1995
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: Autodesk; DTP Studio; Inel; Silicon
Graphics; CAdis; Hewlett Packard; Intergraph
CR; et al

Abstract: The following topics were dealt with: NURBS; animation; curve drawing; radiosity; shading; geometry; rendering; visualization; data exploration; solid modelling; path tracing; CAD; filters; topology; ray tracing; icons; photorealism; multimedia; data compression; 3D scenes; range finding; surface construction; texture; feature-based modelling; stereography; discriminatory analysis; volumetric data; and the graphical representation of rules. Classification: C6130B (Graphics techniques)
Thesaurus: Computer graphics; Data visualisation
Free Terms: Computer graphics; Animation; Radiosity; Geometry;
Rendering; Visualization; Path tracing; CAD; Ray tracing; Multimedia; Volumetric data

95-53
Doc Type: Conference Paper
Title: A comparison of techniques for the transformation of radiosity values to monitor colors
Authors: Ferschin, P.; Tastl, I.; Purgathofer, W.
Affiliation: Inst. fur Computergraphik, Tech. Univ. Wien, Austria Conf. Title: Proceedings ICIP-94 (Cat. No.94CH35708) p. 992-6 vol.3
Publisher: IEEE Comput. Soc. Press
Los Alamitos, CA, USA
Date: 1994 3 vol. (liii+992+1064+1050 pp.)
Country of Publication: USA
ISBN: 0 8186 6952 7
CCC: 0 8186 6950 0/94/$4.00
Language: English
Conf. Date: 13-16 Nov. 1994
Conf. Loc: Austin, TX, USA
Conf. Sponsor: IEEE Signal Process. Soc
Treatment: Theoretical/Mathematical

Abstract: In the rendering process of radiosity scenes, the computed radiosity values have to be converted to color values that can be displayed on a CRT monitor. Usually radiosity calculations as well as various color calculations are performed in the RGB color space. Unfortunately the radiosity values can be outside a monitor gamut, which is a three-dimensional solid surrounding the set of all displayable colors for that device. The radiosity approach can be used either for rendering images with global illumination effects or for accurate physical simulation of light propagation. This paper introduces several techniques to transform radiosity values to monitor colors. These techniques use either clipping or compression, either scene dependent or independent algorithms and work either in the RGB, CIELUV or CIELAB color space. A simple, yet visually appealing, nonlinear color compression technique is introduced to generate smooth intensity gradients on a CRT monitor. The problems of accurate perceptual display of radiosity scenes are discussed as well as some new ideas from color theory are presented that might be helpful for a solution of this task. (12 Refs.)
Classification: B6140C (Optical information, image and video signal processing); B7260 (Display technology and systems) Thesaurus: Brightness; Cathode-ray tube displays; Cathode-ray tubes; Data compression; Human factors; Image colour analysis; Realistic images
Free Terms: Radiosity values transformation; Rendering process; Radiosity scenes; Color values; CRT monitor; Monitor colors; Color calculations; RGB color space; Monitor gamut; Three-dimensional solid; Global illumination effects; Light propagation simulation; Clipping; Perceptual display; Scene dependent algorithms; Scene independent algorithms; RGB; CIELUV; CIELAB; Color space; Nonlinear color compression; Smooth intensity gradients

95-54
Doc Type: Journal Paper
Title: Load balancing and data locality in adaptive hierarchical N-body methods: barnes-hut, fast multipole, and radiosity
Authors: Singh, J.P.; Holt, C.; Totsuka, T.; Gupta, A.; Hennessy,
J.
Affiliation: Comput. Syst. Lab., Stanford Univ., CA, USA
Journal: Journal of Parallel and Distributed Computing
Vol: 27 Iss: 2 p. 118-41
Date: June 1995
Country of Publication: USA
ISSN: 0743-7315 CODEN: JPDCER
CCC: 0743-7315/95/$6.00
Language: English
Treatment: Application; Practical

Abstract: Hierarchical N-body methods, which are based on a fundamental insight into the nature of many physical processes, are increasingly being used to solve large-scale problems in a variety of scientific/engineering domains. Applications that use these methods are challenging to parallelize effectively, however, owing to their nonuniform, dynamically changing characteristic and their need for long-range communication. In this paper, we study the partitioning and scheduling techniques required to obtain effective parallel performance on applications that use a range of hierarchical N-body methods. To obtain representative coverage, we first examine applications that use the two best methods known for classical N-body problems: the Barnes-Hut method and the fast multipole method. Then, we examine a recent hierarchical method for radiosity calculations in computer graphics, which applies the hierarchical N-body approach to a problem with very different characteristics. We find that straightforward decomposition techniques which an automatic scheduler might implement do not scale well, because they are unable to simultaneously provide load balancing and data locality. However, all the applications yield very good parallel performance if appropriate partitioning and scheduling techniques are implemented by the programmer. (29 Refs.)
Classification: C6150J (Operating systems); C6130B (Graphics techniques); C6150N (Distributed systems software)
Thesaurus: Computer graphics; Resource allocation; Scheduling Free Terms: Load balancing; Data locality; Adaptive hierarchical N-body methods; Barnes-hut; Fast multipole; Radiosity; Partitioning; Scheduling techniques; Parallel performance; Barnes-Hut method; Fast multipole method; Radiosity calculations; Computer graphics; Decomposition techniques; Automatic scheduler

95-55
Doc Type: Conference Paper
Title: Radiosity based model for terrain effects on multi-angular views
Authors: Borel, C.C.; Gerstl, S.A.W.
Affiliation: Nonproliferation & Int. Security, Los Alamos Nat. Lab., NM, USA
Conf. Title: IGARSS '94. International Geoscience and Remote Sensing Symposium. Surface and Atmospheric Remote Sensing:
Technologies, Data Analysis and Interpretation (Cat.
No.94CH3378-7)
p. 1667-9 vol.3
Publisher: IEEE
New York, NY, USA
Date: 1994 4 vol. lxviii+2543 pp.
Country of Publication: USA
ISBN: 0 7803 1497 2
CCC: 0 7803 1497 2/94/$4.00
Language: English
Conf. Date: 8-12 Aug. 1994
Conf. Loc: Pasadena, CA, USA
Conf. Sponsor: IEEE; IEEE Geosci. & Remote Sensing Soc.;
URSI; Opt. Soc. America; NASA; Office of Naval
Res
Treatment: Practical; Theoretical/Mathematical

Abstract: The Multi-Angular Imaging Spectroradiometer (MISR) will image the Earth from 9 viewing angles and derive atmospheric parameters and surface reflectance. The authors investigate the effects of reflections within a rough terrain on reflectance retrievals with and without terrain correction. A simple wedge model is used to compute the surface radiosities as a function of solar illumination direction. For the 9 MISR view directions the authors compute the apparent reflectance and compare the results with a single scattering model. For a range of slopes and flat surface reflectances they compute how much the apparent reflectance changes. (6 Refs.)
Classification: A9385 (Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research); A9190 (Other topics in solid Earth physics); B7710 (Geophysical techniques and equipment); B7730 (Other remote sensing applications in Earth sciences) Thesaurus: Geophysical techniques; Remote sensing
Free Terms: Geophysical measurement technique; Land surface terrain mapping; Remote sensing; Optical imaging; Visible; IR infrared; Radiosity based model; Terrain effects; Multi-angular view; Multi-Angular Imaging Spectroradiometer; MIS; Viewing angle; Surface reflectance; Light reflection; Rough terrain; Reflectance retrieval; Terrain correction; Wedge model; Solar illumination direction

95-56
Doc Type: Conference Paper
Title: Are leaf chemistry signatures preserved at the canopy level?
Authors: Borel, C.C.; Gerstl, S.A.W.
Affiliation: Nonproliferation & Int. Security, Los Alamos Nat. Lab., NM, USA
Conf. Title: IGARSS '94. International Geoscience and Remote Sensing Symposium. Surface and Atmospheric Remote Sensing:
Technologies, Data Analysis and Interpretation (Cat.
No.94CH3378-7)
p. 996-8 vol.2
Publisher: IEEE
New York, NY, USA
Date: 1994 4 vol. lxviii+2543 pp.
Country of Publication: USA
ISBN: 0 7803 1497 2
CCC: 0 7803 1497 2/94/$4.00
Language: English
Conf. Date: 8-12 Aug. 1994
Conf. Loc: Pasadena, CA, USA
Conf. Sponsor: IEEE; IEEE Geosci. & Remote Sensing Soc.;
URSI; Opt. Soc. America; NASA; Office of Naval
Res
Treatment: Practical; Experimental

Abstract: Imaging spectrometers have the potential to be very useful in remote sensing of canopy chemistry constituents such as nitrogen and lignin. In this study under the HIRIS project the question of how leaf chemical composition which is reflected in leaf spectral features in the reflectance and transmittance is affected by canopy architecture was investigated. Several plants were modeled with high fidelity and a radiosity model was used to compute the canopy spectral signature over the visible and near infrared. The authors found that chemical constituent specific signatures such as absorptions are preserved and in the case of low absorption are actually enhanced. For moderately dense canopies the amount of a constituent depends also on the total leaf area. (3 Refs.) Classification: A9385 (Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research); A9190 (Other topics in solid Earth physics); B7730 (Other remote sensing applications in Earth sciences); B7710 (Geophysical techniques and equipment) Thesaurus: Forestry; Geophysical techniques; Infrared imaging; Remote sensing
Free Terms: Vegetation canopy; Chemical composition; Tree; Forest forestry; Leaf chemistry signature; IR spectra visible infrared; Remote sensing; Geophysical measurement technique; HIRIS project; Spectral features; Reflectance; Transmittance; Canopy architecture; Radiosity model; Near infrared; Total leaf area

95-57
Doc Type: Journal Paper
Title: A parallel image-rendering algorithm and architecture based on ray tracing and radiosity shading
Authors: Li-Sheng Shen; Deprettere, E.F.; Dewilde, P.
Affiliation: Fac. of Electr. Eng., Delft Univ. of Technol., Netherlands
Journal: Computers & Graphics
Vol: 19 Iss: 2 p. 281-96
Date: March-April 1995
Country of Publication: UK
ISSN: 0097-8493 CODEN: COGRD2
CCC: 0097-8493/95/$9.50+.00
Language: English
Treatment: Practical

Abstract: We explore ways to improving the performance of a ray casting based approach for visualizing artificial scenes with photorealism on the screen of a workstation. We aim at developing a parallel image rendering algorithm and architecture based on the so called two pass approach (J. Wallace et al., 1987). We argue that large speedups and low overheads can only be attained through combined algorithm and architecture design. By attempting this combined effort, we come up with a good algorithm architecture pair, namely, the shelling technique (L.S. Shenm et al., 1990) and a pipelined parallel architecture, in which a parameterized space partitioning on the one hand finds its counterpart in a scalable network of clusters on the other hand. The target system has been completely modelled by using a mixed level simulator called the Block Oriented Network Simulator (BONeS), and we have evaluated its performance for a set of practical scenes. Promising results have been observed, including the following: 1. The performance of the shelling technique is a weak function of the scene complexity. The computational complexity of the shelling technique is k*R (k is about 2 5), where R is the total number of intersection computation rays; a reasonable speedup has been observed up to 8 clusters; the performance of software intersection computation on HP720 is about 0.2 M/sec. (25 Refs.)
Classification: C5540 (Terminals and graphic displays); C6130B (Graphics techniques); C6110P (Parallel programming); C5220P (Parallel architecture); C5440 (Multiprocessing systems); C4240C (Computational complexity)
Thesaurus: Brightness; Computational complexity; Computer graphic equipment; Parallel algorithms; Parallel architectures; Pipeline processing; Ray tracing; Rendering [computer graphics] Free Terms: Parallel image rendering algorithm; Parallel image-rendering algorithm; Ray tracing; Radiosity shading; Ray casting based approach; Artificial scene visualization; Photorealism; Two pass approach; Algorithm architecture pair; Shelling technique; Pipelined parallel architecture; Parameterized space partitioning; Scalable network; Mixed level simulator; Block Oriented Network Simulator; BONeS; Scene complexity; Computational complexity; Software intersection computation; HP720

95-58
Doc Type: Journal Paper
Title: Massively parallel hemispherical projection for progressive radiosity
Authors: Renaud, C.; Bricout, F.; Lepretre, E.
Affiliation: Lab. d'Inf. Fondamentale de Lille, Univ. des Sci. et Tech. de Lille Flandres Artois, Villeneuve d'Ascq, France
Journal: Computers & Graphics
Vol: 19 Iss: 2 p. 273-9
Date: March-April 1995
Country of Publication: UK
ISSN: 0097-8493 CODEN: COGRD2
CCC: 0097-8493/95/$9.50+.00
Language: English
Treatment: Practical

Abstract: The paper describes a massively parallel implementation of the progressive radiosity algorithm. Our algorithm is based on an hemispherical projection approach, which provides an accurate form factor approximation. As the projection plane is mapped onto a processor mesh, we propose different techniques that decrease computation time by reducing processor inactivity as much as possible. This approach successfully handles large sets of form factor sampling elements. (8 Refs.)
Classification: C5540 (Terminals and graphic displays); C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C5440 (Multiprocessing systems)
Thesaurus: Brightness; Computer graphic equipment; Computer graphics; Parallel algorithms; Parallel machines
Free Terms: Massively parallel hemispherical projection; Progressive radiosity; Massively parallel implementation; Radiosity algorithm; Hemispherical projection approach; Accurate form factor approximation; Projection plane; Processor mesh; Form factor sampling elements

1996

96-1
Doc Type: Journal Paper
Title: An efficient SIMD algorithm for radiosity on the MP-1
Authors: Renaud, C.; Bricout, F.; Lepretre, E.
Affiliation: Lab. d`Inf. du Littoral, Littoral Univ., Calais, France Journal: Simulation Practice and Theory
Vol: 4 Iss: 2-3 p. 189-217
Publisher: Elsevier
Date: 15 May 1996
Country of Publication: Netherlands
ISSN: 0928-4869 CODEN: SPTHEH
CCC: 0928-4869/96/$15.00
Language: English
Treatment: Theoretical/Mathematical

Abstract: Radiosity provides high quality synthetic images by taking into account inter-reflections between surfaces. Unfortunately, this method is very time-consuming, because of the evaluation of geometric quantities known as form factors. We obtained substantial time reduction by implementing it on a large mesh-connected machine, the DEC MP-1. In this paper we present a parallel implementation of projective approaches used in the radiosity algorithm. We also detail specific communication problems encountered in implementing the algorithms on the DEC MP-1, and propose some solutions, using coherency properties. (10 Refs.) Classification: C6130B (Graphics techniques); C4240P (Parallel programming and algorithm theory); C6110P (Parallel programming) Thesaurus: Parallel algorithms; Realistic images; Rendering [computer graphics]
Free Terms: Efficient SIMD algorithm; High quality synthetic images; DEC MP-1; Inter-reflections; Geometric quantities; Mesh-connected machine; Radiosity algorithm; Communication problems; Coherency properties; Parallel computing

96-2
Doc Type: Conference Paper
Title: Design of a graphics architecture bridging the cap between modeling and rendering
Authors: Fellner, D.
Affiliation: Dept. of Comput. Sci., Bonn Univ., Germany
Conf. Title: WSCG 96. Fourth International Conference in Central Europe on Computer Graphics and Visualization 96, in
cooperation with IFIP Working Group 5.10 on Computer
Graphics and Virtual Worlds. Conference Proceedings
p. 420 vol.2
Editors: Thalman, N.M.; Skala, V.
Publisher: Univ. West Bohemia
Plzen, Czech Republic
Date: 1996 2 vol. iii+427 pp.
Country of Publication: Czech Republic
ISBN: 80 7082 238 4
Language: English
Conf. Date: 12-16 Feb. 1996
Conf. Loc: Plzen, Czech Republic
Conf. Sponsor: IBM; Hewlett Packard; Intergraph;
Microsoft; Wolfram Res.; DTP
Treatment: Application; Practical

Abstract: 3D graphics had-and still has-not yet become a mainstream technology for everyday application and user interface development. The major reason being that software libraries available did not provide a programming model appropriate for widespread use by developers who are not necessarily experts in 3D graphics programming. The primary goal of the presented project is the design of an object-based (in contrast to drawing-based) modeling and rendering platform consisting of a well structured and extensible set of objects that support all necessary operations to build a full-fledged modeling and rendering system. The 3D objects are the building blocks that lend themselves to programmer customization through techniques such as subclassing. Further to the high-level 3D objects, rendering classes provide access to all levels of rendering algorithms from low-level z-buffering and Gouraud shading to ray-tracing or radiosity. As the name Minimal Rendering Tool (MRT) indicates, we tried to keep the package as minimal as possible. (0 Refs.)
Classification: C6130B (Graphics techn