A centimeter-gram-second (cgs) unit of luminance (or brightness) equal to 1/π candle per square centimeter. Physically, the lambert is the luminance of a perfectly diffusing white surface receiving an illuminance of 1 lumen per square centimeter.
Johann Heinrich Lambert (1728-1777), German scientist and mathematician; → law.
Lambert's cosine law
qânun-e cosinus-e Lambert
Fr.: loi en cosinus de Lambert
The intensity of the light emanating in any given direction from a perfectly diffusing surface is proportional to the cosine of the angle between the direction and the normal to the surface. Also called → Lambert's law.
Fr.: loi de Lambert
Same as → Lambert's cosine law.
gerde-ye Lamberti, disk-e ~
Fr.: disque lambertien
Fr.: surface lambertienne
A surface whose → luminous intensity obeys → Lambert's cosine law. Such a source has a → reflectance that is uniform across its surface and uniformly emits in all directions from all its points. It appears equally bright from all viewing directions. Lambertian surface is a very useful concept for the approximation of radiant power transfer.