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Événements visuels de convexes et limites d'ombres

Julien Demouth 1
1 VEGAS - Effective Geometric Algorithms for Surfaces and Visibility
INRIA Lorraine, LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
Abstract : To compute shadows in computer graphics, it is common to be interested in the view of a geometric scene by an observer. Particularly, it is important to characterize the structural changes, called visual events, taking place in the view when the observer moves. Based on the combinatorial definition of view introduced by Gigus and Malik and the associated classification of visual events, many studies suffer from time and space complexity problems. For example, it is the case of discontinuity meshing. Thus, we suggest a new approach which relies on a questionning about this notion of view.

For a set of pairwise disjoint convex objects, we propose a topological definition of view emphasizing the visible silhouettes of objects in the scene and we geometrically characterize the locus where those visual events take place. We use this characterization to propose a method to extract boundaries between full light and penumbra and between penumbra and umbra in a scene lit by area light sources. We manage to strongly reduce the size of intermediate objects in use to build the limits between those regions.

Furthermore, we prove the first non trivial theoretical bounds on the complexity of the limits between full-light and penumbra and between penumbra and umbra.
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Contributor : Julien Demouth <>
Submitted on : Friday, November 28, 2008 - 12:13:45 PM
Last modification on : Monday, April 16, 2018 - 10:42:10 AM
Long-term archiving on: : Thursday, October 11, 2012 - 12:10:31 PM


  • HAL Id : tel-00342717, version 1


Julien Demouth. Événements visuels de convexes et limites d'ombres. Modélisation et simulation. Université Nancy II, 2008. Français. ⟨tel-00342717⟩



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