imagine the situation that you have only pure white objects in your 3d scene lit equally from all directions by a white light: the result would be a completely white image. nomen est omen: ‘ambient occlusion’ occludes (blocks) a certain amount of rays when blocked by objects in a scene.
as a result, the parts where rays were blocked will become darker – we basically get a white image with darker areas where the geometry intersects with itself which gives us accurate and smooth shadows resembl to global illumination – but with a fraction of the rendering time! with ambient occlusion you give more depth to your scene and details out all the tiny little elements you invested a lot of time in.
since 3dsmax 7/ mental ray 3.3 the new shader “ambient/ reflective occlusion” which can be used for this task. use the shader when you’re finished with your scene and want to give the last polish to it by adding a
quick guide to add ambient occlusion to your image:
method 1: “skylight”
set your renderer to mental ray.
change the background color to white, the global light to 1.0
put a standard material on all objects, set its color white
turn on final gather in the rendering options
delete all your lights in the scene, add a skilight, set its color to white
render the scene
method 2: “shader”
set your renderer to mental ray
change the background color to white and the global light to zero
put a standard material on all objects, set its color to white
place an ambient/ occlusion map in the self-illumination slot
delete the lights in the scene
render the scene
the resulting occlusion pass can be used now as multiplied layer.
the vray rendering system will provide this shader in the version 1.5, which will arrive on the market this autumn. until then, use mental ray.
further reading: