Radiosité dynamique 2D et complexe de visibilité

Rachel Orti 1
1 iMAGIS - Models, Algorithms and Geometry for Computer Generated Image Graphics
GRAVIR - IMAG - Graphisme, Vision et Robotique, Inria Grenoble - Rhône-Alpes
Abstract : The radiosity method is a global illumination simulation method which is widely used for visualization of static scenes (especially interiors). Despite the various improvements that have been carried out until now, the radiosity cost remains dependent on the calculation of the form factors which describe the light interaction between two surfaces. Their computation is the most time-consuming part of the method, because of the visibility calculations involved. Moreover, the use of discontinuity meshing is essential to obtain a good quality radiosity solution. However, its computation is very expensive since it requires many geometric calculations. In addition to that, the methods proposed until now for dynamic environments (environments where the geometry, the material properties, etc., can change) still perform too many recomputations. The remaining problem is the efficient and accurate detection of which form factors must really be recomputed. We have considered the 2D case for which better comprehension and a more thorough analysis are possible, notably thanks to the existence of analytic solutions. We have turned our attention to the visibility complex (introduced recently in computational geometry) which represents the visibility relationships between objects in the plane. In this thesis, we present its use for radiosity computation, first for static environments, and then for dynamic environments. We show that the complex allows us to compute the form factors in an efficient and analytic way, and also to easily construct the discontinuity mesh. Moreover, only the form factors between mutually visible elements in the scene are computed. Finally, in the dynamic case, the complex allows us to identify and then to update only the strictly necessary form factors when an object is moving.
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Rachel Orti. Radiosité dynamique 2D et complexe de visibilité. Interface homme-machine [cs.HC]. Université Joseph-Fourier - Grenoble I, 1997. Français. ⟨tel-00004958⟩

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