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BiDirectional Path Tracing
 PROCEEDINGS OF THIRD INTERNATIONAL CONFERENCE ON COMPUTATIONAL GRAPHICS AND VISUALIZATION TECHNIQUES (COMPUGRAPHICS ’93
, 1993
"... In this paper we present a new Monte Carlo rendering algorithm that seamlessly integrates the ideas of ..."
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Cited by 136 (10 self)
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In this paper we present a new Monte Carlo rendering algorithm that seamlessly integrates the ideas of
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...
Rendering Participating Media with Bidirectional Path Tracing
 In Eurographics Rendering Workshop
, 1996
"... In this paper we show how bidirectional path tracing can be extended to handle global illumination effects due to participating media. The resulting imagebased algorithm is computationally expensive but more versatile than previous solutions. It correctly handles multiple scattering in nonhomog ..."
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Cited by 51 (0 self)
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In this paper we show how bidirectional path tracing can be extended to handle global illumination effects due to participating media. The resulting imagebased algorithm is computationally expensive but more versatile than previous solutions. It correctly handles multiple scattering in nonhomogeneous, anisotropic media in complex illumination situations. We illustrate its specific advantages by means of examples.
Global illumination using local linear density estimation
 Proceedings of SIGGRAPH 97
, 1997
"... This article presents the density estimation framework for generating viewindependent global illumination solutions. It works by probabilistically simulating the light flow in an environment with light particles that trace random walks originating at luminaires and then using statistical density es ..."
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Cited by 45 (6 self)
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This article presents the density estimation framework for generating viewindependent global illumination solutions. It works by probabilistically simulating the light flow in an environment with light particles that trace random walks originating at luminaires and then using statistical density estimation techniques to reconstruct the lighting on each surface. By splitting the computation into separate transport and reconstruction stages, we gain many advantages including reduced memory usage, the ability to simulate nondiffuse transport, and natural parallelism. Solutions to several theoretical and practical difficulties in implementing this framework are also described. Light sources that vary spectrally and directionally are integrated into a spectral particle tracer using nonuniform rejection. A new local linear density estimation technique eliminates boundary bias and extends to arbitrary polygons. A mesh decimation algorithm with perceptual calibration is introduced to simplify the Gouraudshaded
Wavelet Radiance
 In Fifth Eurographics Workshop on Rendering
, 1994
"... In this paper, we show how wavelet analysis can be used to provide an efficient solution method for global illumination with glossy and diffuse reflections. Wavelets are used to sparsely represent radiance distribution functions and the transport operator. In contrast to previous wavelet methods (fo ..."
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Cited by 38 (3 self)
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In this paper, we show how wavelet analysis can be used to provide an efficient solution method for global illumination with glossy and diffuse reflections. Wavelets are used to sparsely represent radiance distribution functions and the transport operator. In contrast to previous wavelet methods (for radiosity), our algorithm transports light directly among wavelets, and eliminates the pushing and pulling procedures. The framework we describe supports curved surfaces and spatiallyvarying anisotropic BRDFs. We use importance to make the global illumination problem tractable for complex scenes, and we use a final gathering step to improve the visual quality of the solution. 1 Introduction Radiosity algorithms assume that all reflection is ideally diffuse. This assumption, while making the computation of global illumination more tractable, ignores many important effects, such as glossy highlights and mirror reflections. Though more expensive, the simulation of directional reflection is e...
Wavelet Methods for Radiance Computations
, 1994
"... This paper describes a new algorithm to compute radiance in a synthetic environment. Motivated by the success of wavelet methods for radiosity computations we have applied multi wavelet bases to the computation of radiance in the presence of glossy reflectors. We have implemented this algorithm and ..."
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Cited by 29 (3 self)
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This paper describes a new algorithm to compute radiance in a synthetic environment. Motivated by the success of wavelet methods for radiosity computations we have applied multi wavelet bases to the computation of radiance in the presence of glossy reflectors. We have implemented this algorithm and report on some experiments performed with it. In particular we show that the convergence properties of basis functions with 14 vanishing moments are in accordance with theoretical predictions. As in the case of wavelet radiosity we find higher order bases to have advantages. However, the cost scaling due to the higher dimensionality of the problem is such that the higher order bases only become competitive for very high precision requirements. In practice we rarely go beyond piecewise linear functions. 1 Introduction One of the main areas of computer graphics research concerns the analysis and synthesis of the propagation of light in a given scene. The goal of this research is the develo...
Using the Modified Phong Reflectance Model for Physically Based Rendering
, 1994
"... This text discusses a few aspects of reflectance models in physically based rendering: ffl The first section presents the definition of the bidirectional reflection distribution function (brdf) of a surface and its physical properties. ffl On a more practical level, the next section discusses mode ..."
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Cited by 26 (0 self)
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This text discusses a few aspects of reflectance models in physically based rendering: ffl The first section presents the definition of the bidirectional reflection distribution function (brdf) of a surface and its physical properties. ffl On a more practical level, the next section discusses models to represent brdfs and their desired properties in general for Monte Carlo algorithms. ffl The third section goes into details about a specific reflectance model, the modified Phong brdf, with its definition, its properties and its use. We show how this model can be correctly integrated in importance sampling schemes for physically based Monte Carlo rendering algorithms. ffl The fourth section is devoted to alternative parameter spaces in which reflectance models can be sampled, either deterministically or stochastically. ffl The last section discusses an important implementational issue, more specifically the problem of verifying the implementation of a reflectance model. Keywords : ...
Global Illumination via DensityEstimation
 Proceedings of 6th Workshop on Rendering (Dublin
, 1995
"... This paper presents a new method for the production of viewindependent global illumination solutions of complex static environments. A key innovation of this new approach is its decomposition of the problem into a loosely coupled sequence of simple modules. This approach decouples the global energy ..."
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Cited by 20 (0 self)
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This paper presents a new method for the production of viewindependent global illumination solutions of complex static environments. A key innovation of this new approach is its decomposition of the problem into a loosely coupled sequence of simple modules. This approach decouples the global energy transport computation from the construction of the displayable shaded representation of the environment. This decoupling eliminates many constraints of previous global illuminationapproaches, yieldingaccurate solutions for environments with nondiffuse surfaces and high geometric complexity. Our algorithm produces a viewindependent display mesh that represents the irradiances on surfaces in a form that allows direct display of the shaded surface. Most traditional radiosity algorithms also use a computational mesh to represent intermediate results in the light transport calculation (e.g., the piecewiseconstant global solution of Smits et al. [17]). Typically, a single representation is used for both the computational and display meshes (e.g. the static mesh used by Neumann et al. [11] and the adaptive mesh used by Teller et al. [18]). Very few display mesh solutions have been produced for environments with more than a few thousand initial surfaces. The only implementation we are aware of that has produced a display mesh for more than 10,000 initial surfaces is the system by Teller et al. [18], which was run on a model with approximately 40,000 initial surfaces. Teller et al. argue that the reason for these surprisingly small limits is the high memory overhead of the data structures associated with the computational mesh. To solve this problem, we draw on an observation by Lischinski et al. [10], that the computational mesh and the display mesh have different purposes and ch...