Représentations hiérarchiques de la visibilité pour le contrôle de l'erreur en simulation de l'éclairage

Cyril Soler 1
1 iMAGIS - Models, Algorithms and Geometry for Computer Generated Image Graphics
GRAVIR - IMAG - Graphisme, Vision et Robotique, Inria Grenoble - Rhône-Alpes
Abstract : Error control is important in a large number of applications of radiative transfer simulation. It allows to ensure a given degree of precision in the computed solution, and also makes it possible to gradually trade computation time for quality in the resulting images. In lighting simulations using hierarchical radiosity methods, the evaluation of visibility relationships constitutes the major part of the total computational effort, making it the ideal target of various approximations that finally influence the image quality. In this work we first study the impact of visibility approximations in the computation of form factors, on the accuracy in the simulation results. Such an approach can be used in coordination with an error control algorithm in the computation of each form factor, to obtain an error driven lighting simulation method. We propose such an algorithm, based on the pre-computation and storage of multi-scale visibility informations. For various applications however, the concept of image quality can be quite different: whereas a mathematical bound on the overall error suffices for most quantitative computations, the application of lighting simulation to image synthesis requires a perceptually based error estimation method. Such an approach must for instance account for all visual artifacts that condition image quality. In this frame of mind, we propose an error driven method for the computation of soft shadows, based on the operation of convolution between images of a source and a blocker. Finally, we present a hierarchical radiosity algorithm that controls the accuracy of the simulation using adequate error estimation methods for both the global energy balance and fine shadow details.
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Theses
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https://tel.archives-ouvertes.fr/tel-00004905
Contributor : Thèses Imag <>
Submitted on : Thursday, February 19, 2004 - 4:37:20 PM
Last modification on : Wednesday, April 11, 2018 - 1:53:53 AM
Long-term archiving on : Friday, April 2, 2010 - 8:36:11 PM

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  • HAL Id : tel-00004905, version 1

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Cyril Soler. Représentations hiérarchiques de la visibilité pour le contrôle de l'erreur en simulation de l'éclairage. Interface homme-machine [cs.HC]. Université Joseph-Fourier - Grenoble I, 1998. Français. ⟨tel-00004905⟩

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