Microfacet BRDF models
Event details
| Date | 20.06.2014 |
| Hour | 15:15 |
| Speaker | Lionel SIMONOT, Université de Poitiers, France |
| Location | |
| Category | Conferences - Seminars |
The volume and surface scattering of a material is usually defined at a macroscopic scale by its bidirectional reflectance distribution function (BRDF) that describes the chance of reflection for different pairs of incoming and outgoing light directions. It is widely used in remote sensing, science material, lighting simulation or computer graphics.
Microfacet BRDF models are based on a geometrical description of the material surface as a collection of microfacets whose dimensions are much greater than the wavelength. The resulting BRDF dépends on the microfacet slope distribution, the shadowing-masking function and the BRDF of the individual facets. In the original Cook-Torrance model, and in most of cases even today, each facet is assumed to reflect light only in the specular direction. The third factor of the model is then given by the Fresnel relation depending on the material refractive index.
We will present the generalization of microfacet models for any radiometric response of the individual facets. Some crucial points (radiometric proof of the model, choice of the distribution and of the shadowing-masking function, numerical calculations…) will be discussed. And we propose to consider facets consisting of a flat interface on a Lambertian background. The Oren-Nayar model distribution of strictly Lambertian facets and the Cook-Torrance model distribution of strictly specular facets appear as special cases.
Microfacet BRDF models are based on a geometrical description of the material surface as a collection of microfacets whose dimensions are much greater than the wavelength. The resulting BRDF dépends on the microfacet slope distribution, the shadowing-masking function and the BRDF of the individual facets. In the original Cook-Torrance model, and in most of cases even today, each facet is assumed to reflect light only in the specular direction. The third factor of the model is then given by the Fresnel relation depending on the material refractive index.
We will present the generalization of microfacet models for any radiometric response of the individual facets. Some crucial points (radiometric proof of the model, choice of the distribution and of the shadowing-masking function, numerical calculations…) will be discussed. And we propose to consider facets consisting of a flat interface on a Lambertian background. The Oren-Nayar model distribution of strictly Lambertian facets and the Cook-Torrance model distribution of strictly specular facets appear as special cases.
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Practical information
- General public
- Free
Organizer
- Roger Hersch
Contact
- Sylvie Thomet