Distribution-based BRDFs

The bidirectional reflectance distribution function (BRDF) formalism is commonly used in computer graphics to represent surface reflection properties. Although many BRDF models have been proposed, most do not possess at least some of the desirable practical properties. In this paper we present a simple and flexible model which satisfies many of these requirements. We show that the proposed model provides a good approximation for many real world materials, obeys basic physical restrictions, allows straightforward hardware implementation and provides for efficient sampling in a Monte-Carlo rendering system. A procedure to fit the model to BRDF measurement data is presented which suggests a simplified way of measuring surface reflection.