Representing BRDF by wavelet transformation of pair-copula constructions

Abstract

Bidirectional Reflectance Distribution Functions (BRDFs) are wellknown functions in computer graphics and these special functions represent the surface reflectance of materials. BRDFs can be viewed as multivariate probability density function (pdf) of incoming photons leaving in a particular outgoing direction. However constructing a multivariate probability distribution for modeling a given BRDF is difficult. A family of distributions namely Copula distributions have been used to approximate BRDF. In this work we employ the Pair-Copula constructions to represent the measured BRDF densities. As the measured BRDF densities have large storage needs we use Wavelet transforms for a compact BRDF representation. We also compare the proposed BRDF representation with a number of well-known BRDF models and show that our compact BRDF representation provides good approximation to measured BRDF data. © 2013 ACM. © 2013 Elsevier B.V. All rights reserved.