title: Directional statistics-based reflectance model for isotropic bidirectional reflectance distribution functions.
abstract: 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.
authors.affiliation: Department of Computer Science, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, USA. kon@drexel.edu
authors.forename: Ko
authors.initials: K
authors.lastname: Nishino
authors.forename: Stephen
authors.initials: S
authors.lastname: Lombardi