Well this is what I got out of it…
Layered the QOcllusion pass over the regular pass and it brought out some highlights and cool things the regular lacks.
I dont know if this is what its for.Its probrably for compositing all the differant passes like rgb and such but I can other uses for it.
Isn´t a dumb question at all.
In this case there are two ways to interpreting the word occlusion: can be obstruction (of light) or absorption (of light) although both cases are applicable to the concept (one by addition and the other one by subtraction) I prefer to interpret it as absorption.
Then basically the ambient occlusion, is a technique to determine the quantity of light absorption of each specific area on a surface. Is said ambient occlusion map, when this is made through normal/vector texture maps (commonly applied in difuse channel) and ambient occlusion pass, when is used multilayering render, making a renderpass (usually with raytrace, radiosity or even deph-maps) or through shaders.
The result is a more realistic aspect since emulates the shady of environmental lighting.
The methods to achieve it, are diverse and they vary depending on software possibilities and genius of artists and programmers, you can even achieve respectable results with spinning lights.
A technique (already old) for PRenderman that I would like to be applied in LW is this:
Edit: To avoid confusions, I should clarify that absorption quantity (or light obstruction) represented in a map or passing, isn´t due to surface properties “per se”, but to direction (angle) and light quantity in relation to a specific surface area.