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A rapid hierarchical radiosity algorithm
 Computer Graphics
, 1991
"... This paper presents a rapid hierarchical radiosity algorithm for illuminating scenes containing lar e polygonal patches. The afgorithm constructs a hierarchic“J representation of the form factor matrix by adaptively subdividing patches into su bpatches according to a usersupplied error bound. The a ..."
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Cited by 405 (11 self)
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This paper presents a rapid hierarchical radiosity algorithm for illuminating scenes containing lar e polygonal patches. The afgorithm constructs a hierarchic“J representation of the form factor matrix by adaptively subdividing patches into su bpatches according to a usersupplied error bound. The algorithm guarantees that all form factors are calculated to the same precision, removing many common image artifacts due to inaccurate form factors. More importantly, the al orithm decomposes the form factor matrix into at most O? n) blocks (where n is the number of elements). Previous radiosity algorithms represented the elementtoelement transport interactions with n2 form factors. Visibility algorithms are given that work well with this approach. Standard techniques for shooting and gathering can be used with the hierarchical representation to solve for equilibrium radiosities, but we also discuss using a brightnessweighted error criteria, in conjunction with multigrldding, to even more rapidly progressively refine the image.
A Ray Tracing Algorithm for Progressive Radiosity, Computer Graphics 23(3
, 1989
"... A new method for computing formfactors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemicube algorithm to determine formfactors. However, sampling problems inherent in the hemicube algorithm limit its useful ..."
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Cited by 123 (0 self)
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A new method for computing formfactors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemicube algorithm to determine formfactors. However, sampling problems inherent in the hemicube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the formfactor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived formfactors and ray traced formfactors are presented.
Monte Carlo Techniques for Direct Lighting Calculations
 ACM Transactions on Graphics
, 1996
"... In a distribution ray tracer, the crucial part of the direct lighting calculation is the sampling strategy for shadow ray testing. Monte Carlo integration with importance sampling is used to carry out this calculation. Importance sampling involves the design of integrandspecific probability density ..."
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Cited by 87 (9 self)
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In a distribution ray tracer, the crucial part of the direct lighting calculation is the sampling strategy for shadow ray testing. Monte Carlo integration with importance sampling is used to carry out this calculation. Importance sampling involves the design of integrandspecific probability density functions which are used to generate sample points for the numerical quadrature. Probability density functions are presented that aid in the direct lighting calculation from luminaires of various simple shapes. A method for defining a probability density function over a set of luminaires is presented that allows the direct lighting calculation to be carried out with one sample, regardless of the number of luminaires. CR Categories and Subject Descriptors: G.1.4 [Mathematical Computing]: Quadrature and Numerical Differentiation; I.3.0 [Computer Graphics]: General; I.3.7 [Computer Graphics]: ThreeDimensional Graphics and Realism. Additional Key Words and Phrases: direct lighting, importanc...
Physically Based Lighting Calculations for Computer Graphics
, 1991
"... Realistic image generation is presented in a theoretical formulation that builds from previous work on the rendering equation. Previous and new solution techniques for the global illumination are discussed in the context of this formulation. The basic ..."
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Cited by 72 (13 self)
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Realistic image generation is presented in a theoretical formulation that builds from previous work on the rendering equation. Previous and new solution techniques for the global illumination are discussed in the context of this formulation. The basic
A Ray Tracing Method for Illumination Calculation in DiffuseSpecular Scenes
 In Proceedings of Graphics Interface '90
, 1990
"... Several ways of improving the realism of the results of traditional ray tracing are presented. The essential physical quantities of spectral radiant power and spectral radiance and their use in lighting calculations are discussed. Global illumination terms are derived by employing illumination ray t ..."
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Cited by 68 (5 self)
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Several ways of improving the realism of the results of traditional ray tracing are presented. The essential physical quantities of spectral radiant power and spectral radiance and their use in lighting calculations are discussed. Global illumination terms are derived by employing illumination ray tracing for calculation of quickly changing indirect lighting components, and radiosity ray tracing for slowly changing indirect lighting components. Direct lighting is calculated during the viewing phase allowing the use of bump maps. Finally, a method is introduced that reduces the total number of shadow rays to no more than the total number of viewing rays for a given picture. Keywords: Bump Mapping, Illumination, Radiosity, Radiance, Ray Tracing, Realism, Stratified Sampling, Texture Mapping. 1 Introduction The quest for accurate lighting models in computer graphics has taken two very different approaches in the 1980s. The first approach is based on ray tracing (point sampling) techniqu...
SÀNDEZ X.: The use of global random directions to compute radiosity. global monte carlo techniques. Ph.D. Thesis. Universitat Politècnica de Catalunya
, 1996
"... ..."
Time Complexity of Monte Carlo Radiosity
, 1992
"... The time complexity of Monte Carlo radiosity is discussed, and a proof is given that the expected number of rays required to produce a statistical radiosity solution below a specified variance for N zones is O(N ). A satisfactory solution is defined to be one in which the variance of radiance estima ..."
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Cited by 21 (4 self)
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The time complexity of Monte Carlo radiosity is discussed, and a proof is given that the expected number of rays required to produce a statistical radiosity solution below a specified variance for N zones is O(N ). A satisfactory solution is defined to be one in which the variance of radiance estimates for each zone is below a predefined threshold. The proof assumes that the radiance is bounded, and the area ratio of the largest to smallest zone is bounded. 1 Introduction In a radiosity (zonal) program, the surfaces in the environment are broken into N zones, z i , and the radiance, L i , of each zone is calculated [6, 7]. In the most straightforward radiosity method, all N 2 relationships (formfactors) are explicitly calculated, so the time complexity of the program is at least O(N 2 ). One of the first schemes to lower the radiosity calculation time was to group the N zones into p patches, and transfer power from patches to zones (elements) [4]. Still, the computation time wil...
An Importance Driven MonteCarlo Solution to the Global Illumination Problem
, 1994
"... : We propose a method for solving the global illumination problem with no restrictive assumptions concerning the behaviour of light either on surface or volume objects in the scene. Surface objects are defined either by facets or parametric patches and volume objets are defined by voxel grids which ..."
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Cited by 18 (0 self)
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: We propose a method for solving the global illumination problem with no restrictive assumptions concerning the behaviour of light either on surface or volume objects in the scene. Surface objects are defined either by facets or parametric patches and volume objets are defined by voxel grids which define arbitrary density distributions in a discrete tridimensional space. The rendering technique is a MonteCarlo raytracing based radiosity which unifies the processing of objects in a scene, whether they are surfacic or volumic. The main characteristics of our technique are the use of separated Markov chains to prevent the explosion of the number of rays and an optimal importance sampling to speedup the convergence. Keywords : Global Illumination, MonteCarlo RayTracing, Importance Sampling, Participating Media. 1 Introduction Solving the global illumination problem is necessary to achieve photorealism in image synthesis [7, 16, 14]. To account for all complex reflection/transmission...
Efficient Parallel Global Illumination using Density Estimation
 Proceedings of ACM Parallel Rendering Symposium, (Atlanta
, 1995
"... This paper presents a multicomputer, parallel version of the recentlyproposed "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 d ..."
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Cited by 11 (2 self)
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This paper presents a multicomputer, parallel version of the recentlyproposed "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 interreflections commonly handled by conventional radiosity methods, this new method can also handle energy transport involving arbitrary nondiffuse surfaces. Output can either be Gouraudshaded elements for interactive walkthroughs, or raytraced 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 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 metho...