CGTalk - Occlusion Pass

warriorash

04-09-2007, 06:11 PM

Hey i dont know if this is a silly Q...

how do we do an occlusion pass for an interior room .. ??

the scene becomes very dark when rendered with the walls of the room ...

but when i hide the outer walls occlusion renders out perfectly...

i duno how really the occlusion works,but from my observence here i guess the light is emitted from an spherical enviormment from all directions. like kind of an IBL on sphere..
so when i the room is closed no light going through it and hence a dark image.

well in tht case how do i get an occlusion... do i need to add some lights into it

BTW i am using Maya 8 and preset occlusion in Layer renders.
thanks

soulburn3d

04-09-2007, 06:51 PM

I don't use maya, however, most occlusion shaders have something called maximum distance, or some variation, which defines how far a ray travels before it considers itself non-occluded. Turning this number smaller is how to get occlusion in an interior space. Maybe what you're using has something like this?

- Neil

warriorash

04-10-2007, 03:36 PM

oops i cudnt find something like that in maya ..

I am using Maya 8.0 , and the occlusion is from the preset of RenderLayers.

jeremybirn

04-10-2007, 04:28 PM

oops i cudnt find something like that in maya ..

I am using Maya 8.0 , and the occlusion is from the preset of RenderLayers.

The preset assigns a Surface Shader as a shader override for the layer, and the Surface Shader's Out Color is mapped with a Mental Ray Ambient Occlusion Texture. The Ambient Occlusion Texture has a max distance, and you should set it as Neil suggested. If you don't want to bother opening Hypershade, you can also click the shader icon next to the render layer, and click the arrow next to the out color in the surface shader, to get to the texture you are adjusting.

-jeremy

warriorash

04-10-2007, 05:34 PM

Thanks a lot jeremy , it works fine now....
i was tryin to render out the occlusion pass for the haunted hallway scene !

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