Lambertian surface

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In the world of 3D computer graphics and visualisation, there exist many methods of representing how light sources interact with other objects in a virtual scene. These objects can be given certain properties such as: reflectivity, opacity, shading, smoothness, colour and texture. All of these (or particular combinations) can help increase the perceived reality of a virtual scene.

The term Lambertian surface refers to a technique used to light particular surfaces of virtual objects within a scene. This technique causes all closed polygons (e.g. a triangle within a 3D mesh) to reflect light equally in all directions when rendered. The effect this has from the viewer's perspective is that any rotation, scaling or translation of an object rendered in such a way does not result in a change of the shadows and highlights of the object's surface.

One way of thinking about how this might look is by imagining a human face in an empty room, lit only by a single light bulb mounted to the ceiling. If the face were to turn to either side then one would assume that the shadow cast by the nose of the face would move from under the nose to cheek to cheek. However if the surface of the human face were to be rendered in a 3D scene as a Lambertian surface, the shadow would stay in the same place - no matter how much the head turned away from the light source on the ceiling.

If we were to enlarge a cross section of a Lambertian surface, we would see a rough (or jagged) surface. So, there are no preferred angles of reflection.

Lambertian surfaces are also called diffuse surfaces.