We introduce a novel parametric bidirectional reflectance distribution function (BRDF) model that can accurately encode a wide variety of real-world isotropic BRDFs with a small number of parameters. The key observation we make is that a BRDF may be viewed as a statistical distribution on a unit hemisphere. We derive a novel directional statistics distribution, which we refer to as the hemispherical exponential power distribution, and model real-world isotropic BRDFs as mixtures of it. We derive a canonical probabilistic method for estimating the parameters, including the number of components, of this novel directional statistics BRDF model. We show that the model captures the full spectrum of real-world isotropic BRDFs with high accuracy, but a small footprint. We also demonstrate the advantages of the novel BRDF model by showing its use for reflection component separation and for exploring the space of isotropic BRDFs.
© 2011 Optical Society of America
Original Manuscript: September 14, 2010
Revised Manuscript: November 11, 2010
Manuscript Accepted: November 11, 2010
Published: December 16, 2010
Ko Nishino and Stephen Lombardi, "Directional statistics-based reflectance model for isotropic bidirectional reflectance distribution functions," J. Opt. Soc. Am. A 28, 8-18 (2011)