Lambertian reflectance

Diagram of Lambertian diffuse reflection. The black arrow shows incident radiance, and the red arrows show the reflected radiant intensity in each direction. When viewed from various angles, the reflected radiant intensity and the apparent area of the surface both vary with the cosine of the viewing angle, so the reflected radiance (intensity per unit area) is the same from all viewing angles.

Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of a Lambertian surface to an observer is the same regardless of the observer's angle of view.^[1] More precisely, the reflected radiant intensity obeys Lambert's cosine law, which makes the reflected radiance the same in all directions. Lambertian reflectance is named after Johann Heinrich Lambert, who introduced the concept of perfect diffusion in his 1760 book Photometria.

^ Ikeuchi, Katsushi (2014). "Lambertian Reflectance". Encyclopedia of Computer Vision. Springer. pp. 441–443. doi:10.1007/978-0-387-31439-6_534. ISBN 978-0-387-30771-8. S2CID 11390799.

[Ikeuchi14-1] Ikeuchi, Katsushi (2014). "Lambertian Reflectance". Encyclopedia of Computer Vision. Springer. pp. 441–443. doi:10.1007/978-0-387-31439-6_534. ISBN 978-0-387-30771-8. S2CID 11390799.

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