Computer Graphic Rendering of Material Surfaces
Oregon BRDF Library
The Oregon BRDF Library (OBL) is a compilation of a wide range of BRDF functions constructed over the previous 30 years in the fields of physics and computer graphics. OBL offers a uniform, object oriented interface in C++ to this collection of BRDF functions, and is flexible enough to incorporate future BRDF models.
The BRDFs included in OBL are:
- Lambertian Diffuse Model
- Minnaert Limb Darkening Model
- Blinn Cloud & Dusty Surface Model
- Cook-Torrance Specular Microfacet BRDF
- Oren-Nayar Diffuse Microfacet BRDF
- He-Torrance Comprehensive Analytic Model
- Ward Anisotropic Model
- Lafortune Generalized Cosine Lobe Model
- Beard-Maxwell Bidirectional Reflectance Model
- Phong Model
- Poulin-Fournier Anisotropic Model
- Arithmetic BRDF
A few of these BRDF models are shown below in Figures 3 and 4.
Figure 3: Phong reflection model (left), Oren-Nayar Diffuse Microfacet BRDF (right). Figure 4: Cook-Torrance Specular Microfacet BRDF (left), He-Torrance Comprehensive Analytic Model (right).
Because of the uniform, object oriented C++ interface across all BRDFs, once a program is built for use with one BRDF model, substitution of any other is trivial. For this reason OBL has proven itself to be a useful and versatile tool. It has been used as the BRDF interface for a BRDF visualization system. A tool was created which determines the correspondence between the BRDF models of OBL and standard appearance scales. It has also been utilized extensively to provide the BRDF values for realistic image synthesis.