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Compositing Ambient Occlusion and channel based lighting.
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Compositing Ambient Occlusion and channel based lighting.
Deke Kincaid, updated 2005-08-25 13:28:53 UTC 120,411 views  Rating:
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The Scene:



Here is a model I have downloaded from ZJ over at deathfall.com, which he used for his Depth Mapped AmbOcc in Renderman tuts. His stuff rocks ! It inspired me to find an out of the box way of doing ambient occlusion in Maya. This is a compositing tutorial so I will focus on that side of things. I am making the Maya file available and have placed extensive notation in the scene. If you want a full rundown on the 3d techniques email me and I will write something.


The Passes

The Diffuse / Texture Pass :

A pass containing only the texture/diffuse colour mapped on our object. Rendered using a single ambient light with ambient shade set to 0 to give a constant shaded render.

The Ambient Environment Pass:

This a render from mental ray, created using the IBL dome feature in Maya v6, I have place an image in the texture slot of the ibl dome. Using the �Dirtmap� shader I unchecked Probe geometry and checked the Use Environment setting. Giving us a pass which samples the ambient environment.

The Occlusion pass:

White isn�t it ! Again output from mental ray using �Dirtmap� Here I have checked Probe Geometry and unchecked Use Environment. I have also set the camera�s background colour to white !

The RGB Light pass:

I have just placed a white shader on my object and put in three directional lights. Colouring each one red, green or blue alternatively. This will give us variable control of lighting based on colour channels. Again using mental ray

The Shadow Pass:

A shadow only pass. Pictured here is the alpha channel. This shadow corresponds to the �red� light in the rgbPass. Rendered using mental ray.

The Depth Pass:

Yes I can here the cries now! This a �faked� depth pass created by projecting a �black to white� ramp along the camera�s zAxis. I have parented this projection to the camera and turned the camera�s Background colour to white. Rendered in mental ray for consistency.

The BG Pass:

A render of the image used in the IBL dome. The �beach probe� from debevec.org (we owe him so much ) Again a mental ray render !
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Author: Deke Kincaid
Submitted: 2005-08-11 11:48:56 UTC
Tags:
Software: Shake
Views: 120,411

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