Everflow Tutorials: Max 7: Ambient Occlusion

This model has a displacement map on the horn 'nubs'. This map shows the wear and tear that the friction of the metallic horns have wreaked. The diffuse map contains red coloring in this area as well to enhance the effect. MentalRay displaces the geometry, changing it, as opposed to a bump map. The problem occurs when you place the standard Ambient Occlusion effect over the render. In order for the Occlusion to 'fit' the renders, is to add the displacement to the Ambient Occlusion passes as well.

Diffuse / Displacement and Occlusion Displacement

The first step is to make sure you do not have material override on. We will be using a custom Ambient Occlusion Material for the head with the added displacement. The rest of the objects in the scene will contain a standard Ambient Occlusion Material. Since the material override applies one material to the entire scene, we must disable it.

Next we will make a copy of our original Ambient Occlusion Material. In this instance I renamed this new material AO Displacement.
I will not go into the details concerning Mental Rays Displacement, it is simply a grayscale image denoting the areas/amount of displacement. The wireframe is illustrated here for your reference.

We will drag and drop the map from the Displacement in the Extended Shader slot from my skin shader into an empty slot. Select Instance when prompted.

Select your AO Displacement Material. Drag the Displacement Map into the Displacement Slot under the Extended Shader's of the AO Displacement Material.

Apply the AO Displacement Material to the Object that has the Displacement. Next Invert the selection, choosing every other object in the scene.

Apply the standard AO Material to the rest of the objects to the scene. Remember the background should be white without any Environment map. Press render. Jump for joy. Or in this case, run in fear.