So, in my typical workflow I need specifically 3 channels to do post production work.
- Alpha Channel (provided upon render export)
- Material ID
- Line-work Overlay
The most important channel is the Material ID channel, because i allows me to quickly select a color in post production to adjust or edit a material/texture after the render. This can be done in one of two ways; The first is in SketchUp, and is done by setting the view port render too only show colors, not textures, and turn off line-work and shadows. This gives be a pretty decent faux-Material ID pass to work on when compositing images. The other way to do this is in V-Ray, by rendering out the Material ID channel. Either way this is very useful in post production. I see it as being as simple as automatically generating random contrasting colors for each type of material and just having the option to export it out when you render.
The next most important channel or element that I use is a line-work pass (usually out of SketchUp). Essentially I export a simple black line over white background. This allows me to composite the two in post production using a multiply layer, and then control the visibility of the line-work or remove it completely. Currently I cant do this in Enscape because I don't know of a way to override all materials so that I can export out only line-work. It would be amazing if Enscape had a simple Line-work material override that could be exported, similar to the foam option, but with no background and pure white. This is a similar request to the post here: Displaying line work in SketchUp+Enscape but I don't know of a way to export only the line-work.