RGB Multimatte workaround

[DIO]

Hi everyone,

Maybe this is nothing new to a lot of people, but I want to share it anyway.

Since I was always hoping for some kind of RGB Multimatte Render Element like in Vray that never came,
I was playing around with the new version trying to find some kind of workflow to get RGB Masks out of Octane, that also
work with Motion Blur and DOF.
The render Layer ID Mode in the new versions is great, but I can render only one ID at a time and the Layer ID Mask Element ignores DOF and Motion Blur.
Object ID and Material ID are both useless for compositing in Fusion, since the colors are random.

I remember trying this a year ago or so, but I didn´t manage to stop the emission nodes from actually emitting light.
So this is what i came up with with 2.23.
Renders fast and works pretty well. The colors render out as perfect red, blue and green channels.
On the right side ot the image you can see the difference between a direct colored Octane rendering and the black and white Render with
mulitplied colors using the RGB Mask channels in Photoshop. Of course it doesn´t work perfectly on the edges between blurred object,
but I don´t think it would work better in Vray with the Mulitmatte Element and DOF or motion blur enabled.

With setting up and rendering my animation as multiple RGB Render scenes
I can finally use dof and motion blur in animations and still having the possibility to grab all my objects almost perfectly in compositing.
Before that I had to use the scanline renderer with selfillu Materials --> no DOF and Motion blur and I always had problems with edges since
the antialiasing was differnt.

Hope this helps