Numerical verification of bidirectional reflectance distribution functions for physical plausibility
Bernardt Duvenhage, Kadi Bouatouch, D.G. Kourie · 2013
The implementations of a couple of often used Bidirectional Reflectance Distribution Functions (BRDFs) are numerically verified against the three conditions for physical plausibility. These conditions are positivity, symmetry (sometimes referred to as reciprocity) and conservation of energy. The focus of this paper is the numerical tests implemented to analyse and verify the BRDF implementations as physically plausible. A concise list of BRDF formulas, modified as required for physical plausibility, is however also presented which to the authors' best knowledge has not yet been presented in the literature.