I am currently trying to make a render with passes (with MENTAL RAY) and i would like to know if i make it wrong:
_Diffus passe (i make a render with lighting+light in ambiant only+without shadows)
_Shadows (i put a white materials to all objetx and i render with shadows_i make this because this is the only way i find to get the shadows on the objets and the shadows of the objet on the environement)
_speculare passes (black materail with a specific speculare value for each kind of materials)
But when i Mix all this i don't have the same image that the original with GI, and my image is to much dark.
I could post example if u need more, But if someone get a good tutorial or advise to make render with different passe with Mental Ray; i will be happy to see it :)