Hemispherical Rasterization for Self-Shadowing of Dynamic Objects

We present a method for interactive rendering of dynamic models with self-shadows due to time-varying, low- frequency lighting environments. In contrast to previous techniques, the method is not limited to static or pre- animated models. Our main contribution is a hemispherical rasterizer, which rapidly computes visibility by ren- dering blocker geometry into a 2D occlusion mask with correct occluder fusion. The response of an object to the lighting is found by integrating the visibility function at each of the vertices against the spherical harmonic func- tions and the BRDF. This yields transfer coefficients that are then multiplied by the lighting coefficients to obtain the final, shadowed exitant radiance. No precomputation is necessary and memory requirements are modest. The method supports both diffuse and glossy BRDFs.

Authors: 
Jan Kautz (MIT)
Jaakko Lehtinen (Helsinki University of Technology and Remedy Entertainment)
Timo Aila (Helsinki University of Technology and Hybrid Graphics (NVIDIA)
Publication Date: 
Tuesday, June 1, 2004
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