Physically Based Rendering

Attempt to model light transfer using phsically based models like BRDFs .

Microfacet Theory #

Microfacets

Probability Density Distribution Function #

• Returns scalar value
• of the fraction of microfacets with normals
• Should be normalized to obey energy conservation

The Beckamnn PDFs are often used.

Why is Phong lighting not physically acurate? #

Phong Lighting doesn’t fulfill the properties of a BRDF :

The specular component violates:

1. Energy conservation

2. Helmholtz reciprocity