Lighting Design Glossary

Lambertian Surface
Lamberts Cosine Law
Matte

(Term of radiometry/photometry)

A lambertian surface is a surface of perfectly matte properties, which means that it adheres to Lamberts cosine law.

Lamberts cosine law states that the reflected or transmitted luminous intensity in any direction from an element of a perfectly diffusing surface varies as the cosine of the angle between that direction and the normal vector of the surface. As a consequence, the luminance of that surface is the same regardless of the viewing angle.