A Fast Interpolation Method to Represent the BRDF in Global Illumination

Abstract

Global illumination that simulates realistic lighting environments makes use of bidirectional reflectance distribution functions (BRDF). Such a function is a surface property, describing how light is re-emitted after hitting this surface. The present paper details a representation of BRDF and radiance distributions, based on control points, that aims at performance. It uses spherical triangles for interpolation, least square mean or linear programming for optimal representation, and very fast rotation by precomputing control points reweightening. It has some more advantages for deforming an existing shape. This approach is compared to Spherical Harmonics, and outperforms this last one.