A Lambertian surface for reflection is a surface that appears uniformly bright from all directions of view and reflects the entire incident light. Lambertian reflectance is the property exhibited by an ideal matte or diffusely reflecting surface.
The brightness of a Lambertian surface appears uniform from any direction of view; in other words, the luminance of the surface is isotropic. Lambertian surfaces are often referred to as ideal diffusion surfaces.
The reflection of various surfaces is described using their BRDF (bidirectional reflectance distribution function) values. All Lambertian surfaces are said to obey the Lambert’s cosine law and hence the BRDF value for these surfaces is a constant value.
Lambertian reflectance surface models are considered as an extreme scenario where the surface roughness is equal to zero. Lambertian reflection is used in computer graphics to show diffuse reflection.
The intensity of the images when viewed through such surfaces changes in proportion with the illumination directions. Unfinished wood is an example of a natural Lambertian surface. Spectralon is a material that has been specially designed to exhibit near perfect Lambertian reflectance.
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