Determine the Components of Illumination
The light reaching the eye when looking at a surface has clearly come from a source (or sources) of illumination and bounced off the surface. In fact the light reaching the eye can be considered as being made up of 3 different components :
- that from diffuse illumination (incident rays come from all over not just one direction)
- that from a point source which is scattered diffusely from the surface
- that from a point source which is specularly reflected.
We will consider each of these components separately and then combine them into one.