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Old 10-12-2012, 12:40 AM   #1
washington , USA
Join Date: Jun 2011
Posts: 69
Simple compositing question

Hello. I am new to composting, but I understand the interface, and generally how Nuke works. I have looked high, and low on how to composite these passes, but I have had no luck.
I have a few scenes that i have rendered out of Maya with Vray, with the exr(multichannel) image format. The Passes that I have rendered out are, diffuse, GI, Lighting, Specualr, and Zdepth. Where I am running into trouble, is how do I get the channels arranged, in a way where i can look at them in the viewer, and the image looks like the beauty image, but I have the control to tweak the elements separately. I understand using the shuffle node to seperate the different channels, but I do not know the order in which to merge them, What shouldd go in the background, and then I am confused the operation that should be used. I have tried a few other methods, but I have not had any success.

Should I be using more render elements? My scene is pretty big, and I did not want to render out an ambient occlusion pass, is it necessary to get a successful composite? I am learning all of this by myself, so any help is appreciated. Thanks!
Old 10-12-2012, 01:47 AM   #2
James W
Wellington, New Zealand
Join Date: Jun 2012
Posts: 166
With Blender's render passes, I have to add the glossy to the diffuse, so that may be what's needed here. Not sure about the lighting passes but I assume they would be combined on top of the color passes with either an add or screen operation. GI might be either a multiply or add/screen. Z-depth is used to create atmospheric effects so it may not be needed to replicate the beauty render.
"For what is a man profited if he gains the whole world but loses his own soul?"

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Old 10-12-2012, 08:50 AM   #3
michael vorberg
digital compositor
stuttgart, Germany
Join Date: Sep 2009
Posts: 639
in this thread i posted some links to tutorials on vray passes:
Old 10-17-2012, 10:35 PM   #4
Christopher Halder
Lisbon, Portugal
Join Date: Apr 2008
Posts: 63
Hey Bigwil357,

There are a few ways to separate the channels. The one I usually use is by shuffling out the channels with a shuffle node (as you pointed out).

To bring them back together I use merge nodes.

For example if you have DIFFUSE, SPECULAR, REFLECTION you merge DIFFUSE and SPECULAR with a plus operation, being DIFFUSE B and SPECULAR A.

After that you merge the former merge with REFLECTION but through a Multiply operation so that you can link to a copy operation (alpha-alpha), that is linked from the source material to this new merge. If you didn't pull the alpha back in, the source footage would come out "ghostly".

Connect to this copy node to the background footage with a merge and you are ready.

P.S - I just noticed i made a bit confusion out of this, so if you need any more help, just let me know.
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Last edited by Xistel : 10-17-2012 at 10:38 PM.
Old 10-17-2012, 10:35 PM   #5
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