Can someone explain what the “coverage” render element does and how to use it? I’ve done a bit of looking and can’t find a word written about it anywhere.
Thanks!
As far as I know it’s an aliasing related pass. Not sure how to use it though. I would like to know more too.
The Maya “Coverage” render element contains the aliasing data of the render. It is being used within other render elements, like V-Ray Multi Matte for an example. You may also use it to create selection masks in photo editing software.
In more technical terms, it is the percentage of the pixel covered by the object which most contributes to the pixel (it is the same object which goes into the RenderID/ObjectID render element for that pixel).
Best regards,
Vlado
So, what’s the right way to use it in the post process?
I tried to get into it some time ago (there was a tut for Fusion with objectIDs), but the results were not really useable (edges not really clean). Is anyone actually using coverage passes? In conjunction with objectIDs? Or in other ways?
I hope someone else can answer that as I don’t really know - people wanted it, so we just implemented it 
Best regards,
Vlado
If Im not mistaken, when I asked one of our compositing td’s how would one use coverage, the reply I got was: you can use it a filter mask when you apply pixel filtering in comp, never really had any success with it though. Remember that in some cases like rendering thin fine lines, there is no alternative for filtering with the renderer during the render time.