Creating an AO pass from a scene with displacement shaders

JordanW

I'm using mental ray and 3dsMax2009.

I want to create an Ambient Occlusion pass of a scene that I have created. The scene has a lot of materials with displacement maps which prevents me from just going to Render->Processing and using the Material Override tool. Is there an easy way to get an AO pass on everything while keeping each material's displacement? The only way I've been able to come up with so far is to make a generic AO material then a custom AO material for each material that has displacement, as you can imagine this would be super tedious to setup/apply each time I wanted to do a render.

omegalith

I am also having a similar issue, will keep an eye on this thread. I tried adding AO to the render layer as an extra pass, but if I go into the AO folder, the image is not AO, it looks like it's the alpha map.

Bryan Cavett

Just did a test that seemed to work for me.

Under Render Elements choose "mr Shader Element" then assign it a ambient occlusion shader in the "parameters" tab. This will spit out a second render pass whit your AO.

JordanW

that does work! Although it breaks transparent object (renders them as solid). So i think i'll try another method, which sinistergfx pointed me to: Put an omni light with ambient only and set it's light shader as ambient occlusion and render a lighting pass..... <edit> This also breaks on transparent objects /shakes fist at air.

I'll keep your posted method in mind though cause that's a neat trick I could use for other things.