Ambient, Diffuse, Specular
The PointLights are treated as SceneObjecte and freely positionable. The light consists of ambient, diffuse and specular parts.
Ambient Backside Occlusion
With Ambient Backside Occlusion the normals of the backside are also taken into account.
An occlusion map in the alpha channel of the RGB texture is used to define the areas that darken RGB and Specular. So it is easy to simulate soiling or deep dark areas.