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Reflection Pass Problem
I have been banging my head against a wall all day, trying top figure this one out.
I have a scene with an object I designed in the middle. Surrounding this object are two walls and a floor. Each wall has a material on them with 100% reflectivity. I want to be able to use the reflections that I get from them and composite them in After Effects.
I cannot seem to get the look that I am going for. When I create a “Reflection” pass in the render settings, I get the proper reflections but not alpha to composite them with.
I then create an “Object Buffer” pass for the reflective walls, but then I get an alpha for both the walls, but not the reflections on the walls.I just want to be able to comp the reflections that I get for the walls, not the walls themselves.
Help.
Please.Thanks
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3 Replies
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You don’t need an alpha channel to composite the reflection pass. Generally the way it works is that you render out a pass for each channel that’s needed to form the complete image. So in your case you might need a diffuse pass, a specular pass, and the reflection pass. In a compositing program you would then layer the reflection pass (add mode) over the specular pass (add mode) on top of the diffuse pass, to create the complete image.
OTOH, if want to isolate the walls, you could give your wall object(s) a compositing tag and render out an object buffer (which is simply an alpha for the objects affected by the tag). The comp tag has a “buffers” tab where you check off a buffer number. Then you need to add a corresponding buffer number in the render>multipass dialogue.
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Using the reflection pass, I have tried the transfer mode method as well and it does not work.
I have tried add, screen, multiply, etc. The result is always a reflection that is semi transparent and is not accurate to what I rendered out of C4D. -
Can you post a scene file?
Craig Whitaker
MFA Candidate
New York University
http://www.craigwhitaker.net
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