Lambertian reflectance is the ideal diffuse-reflection model with direction-independent outgoing radiance, the frequency-integrated specific intensity. If a fraction of incident radiant flux is reflected, a surface receiving irradiance has reflected radiance . The reflected outward power per area is by the same hemispherical integral used for radiant exitance. Its radiant intensity still acquires the projected area factor in Lambert's cosine law.
For and , the reflected radiance is . A patch of area reflects in total, and its radiant intensities at and are respectively and . The radiance stays fixed as the view changes, provided the illumination stays fixed. Changing the incident angle can change irradiance and therefore the reflected radiance.
Articles by others on the same topic
Lambertian reflectance is a model used to describe the way a surface reflects light. It is based on the Lambertian surface concept, which assumes that the surface reflects light equally in all directions, regardless of the angle of incidence. This type of reflectance is characterized by its matte or diffuse appearance, meaning that the surface does not produce specular (mirror-like) highlights.