View Full Version : How do you use Object ID/Material ID in nuke?

03 March 2010, 05:24 AM
In Fusion it is a relatively straightforward process to use a object id pass as a filter/mask in a operation.

I simply want to use a object ID pass, that has solid colors for the object groups in their ID, as a mask for a color correction.

Again, in fusion this is a simple channel boolean, i have no idea how to use this pass in nuke.

Thanks for any help.

04 April 2010, 05:05 AM
you can do it a few different ways. if your ID pass is R,G, or B then you can mask it into the color operator with the check boxes. If your color is is C M or Y then you can use a combination of the checkboxes to acheive CMY... if that makes sense. If your ID pass is black and white all you have to do is drag the mask input of the operator onto the read file.

04 April 2010, 06:31 AM
Keep in mind that object ID passes aren't AA'ed, and therefore aren't particularly useful as masks most of the time.

04 April 2010, 09:47 PM
ObjectID passes are use on the whole with a Coverage pass, because this pass contain sub-pixel data corresponding to AA pixels.

Using independent RGB passes normally you can set coverage pass as mask over IDmatte pass.

However, if you use embed extradata format files (like .EXR) then I don't know how use this data in Nuke. I think that you need extract this data from .exr for using it as channels into Nuke. Maybe with the Shuffle op.

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04 April 2010, 09:47 PM
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