SIGGRAPH Asia 2009 Course Exploring the Potential of Layered BRDF Models

This course serves as a guide on the considerable potential of layered surface models. The key advantage of using such layered BRDFs over traditional, more general shading language constructs is that the end result is automatically highly physically plausible. In particular, we demonstrate on a simple layered surface model that combines several traditional BRDF components how a surprisingly large number of interesting and important surface types can be efficiently represented by using the same, not particularly complex, BRDF code. We also show how handy such an approach is for the eventual end user, whose main concern is the ease with which one can describe object appearance based only on a few intuitive parameters. We first discuss layered surface models in computer graphics and the constraints of modelling object appearance in a physically plausible fashion. We then demonstrate the techniques that can be used to efficiently evaluate layered BRDF models, give examples of the surface types that can be described in this way. We also go beyond plain surface models, and showcase how a texture-based combination of layered surface components can be used to describe highly complex object appearance attributes, while implicitly remaining physically plausible.