Renderman Layers, Matte objects, Matte ID Workflow How & Why

#1

Hello!

I am wondering how to go about rendering an object with several elements/materials, in a scene with foreground middle and background. And within those separate layers, how should I approach

For example, i would like to render out the car with the character separate, the logo, lights, grille, silver trim, etc…all separately. I understand how to make holdouts, but do I have to make each layer a separate render layer, or is there an easier approach? Im trying to use the geometric settings, contribution maps together, but its just not working out correctly.

I am trying to make several objects MATTE OBJECTS/ HOLDOUTS in Renderman using the geometric settings, is there a way make a separate render layer into MATTE OBJECTS or any other attribute, without effecting the objects in all of the other layers? The renderman options are not available in the ATTRIBUTE SPREADSHEET. Is there only way of doing this to use the LAYER OVERRIDE in every object? Seems like there should be a faster way of doing this?

Now here is the question about masking. If you mask with only RED, GREEN, and BLUE, then what do you do when you have more than 3 materials that you want to adjust separately? I can see why rendering 3 materials at once can save time by not rendering all 3 separately, but what do you do when you have 9 materials on a single object? Render all 3 separately, mask all 3, and do that 3 different times? Sometimes I see in breakdowns Purple, and Light blue masks. Are these just made from the preset colors on the color picker?

Thanks in advance

#2

Is there any specific reason to render ALL objects separate?
It doesn’t make sense really, and is just an overkill of work, render- and comping wise.

If you want to color correct later on, it makes more sense to just create a matte pass, and give all objects a unique color. There’s a lot of scripts for that.
Separating your scene into background, object, foreground is simple, and often done for compositing reasons.
Also, have a look into AOV’s, or Renderpasses as they’re called in Maya to separate your renders even more for tweaking later on.

rob