Da uma olhada nesses links, acho que vão ajudar!
http://www.andrew-whitehurst.net/amb_occlude.html
http://www-viz.tamu.edu/students/bmoyer/617/ambocc/
No google você acha bastante coisa
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Ambient Occlusion
[quote:cdd9639149]Recently, a new technique for lighting photorealistic scenes has been developed by several VFX companies. It is called ambient occlusion and works basically like this. For any given scene, you render a pass or texture map that determines how much ambient light hits any given point on a surface. i.e. a lot less light illuminates my armpit than the top of my head. This level of ambient light is independent of the actual main light source used to illuminate the scene. Once the ambient occlusion pass has been rendered, the indirect lighting contribution to the scene is then calculated by applying an environment map of the scene into which the object is to be integrated. This ambient light is attenuated by the previously rendered ambient occlusion pass, thus the top of my head would receive a great deal of illumination, whilst my armpit would remain darker. [/quote:cdd9639149]