This demo shows how to integrate what comes out of MARI into your nuke projections. The Nuke/MARI Bridge is still kind of new and I think people are not sure really how to utilize it yet. To my knowledge, there is nothing like this article out there that explains how to integrate MARI into Nuke from a matte painting point of view. All that I have posted here are things that I have explored and developed myself--I think this is cutting edge of matte painting right now.
In the below image, on the left, is a pillar that is comprised of 4 projections setup in Nuke. On the right is the MARI paint (not the best example of what MARI can do--you can take it a lot farther and do a lot trickier stuff but it was fast to do).
MARI can export 2 types of elements back into Nuke.
Not only can you send back a UV texture but you can send back multiple UV patches (or UDIMS) for one piece of geo. Nuke does not understand multiple UV patches natively but I created a gadget where you can read in all your UV patches into one node and then it correctly gets applied to the geo.
This screen grab below shows a normal Nuke multi projections setup plus multi texture patchs applied to a obj on top of the projections. This is how it works. You can bring all your projections into MARI and bake them into your geo. Then you paint on a new layer in MARI and export just the new layer. The new layer can be painted across multiple UV patches and all the patches will be exported together as part of the same layer MARI. Bring all the patches into Nuke and use my gadget to apply the patches correctly to the geo.
This screen shot shows what it looks like if you totally replace your Nuke projections with UV textures. This is really a nice option to be able to do this and it gives you the ability to bring your geo back into Maya as a fully textured object.
To set up your geo you need to layout UVs. You do not need to lay out your UVs nicely at all--all you need to do is a quick automatic mapping. Make sure none of your UVs are overlapping, however (MARI does not like that). You can see here that I have my object's UVs chopped up into four UV patches (or UDIMS). Each of these patches will get a 2k texture map.
You can see here that I chopped up the UVs in a way that roughly would give me enough resolution in the areas that I needed. Cutting up the UVs is based on the resolution you want which is based on the camera move. If the camera gets close to a particular area of your geo, then you will want to isolate that area and make sure those UVs are on its own patch and the texture is high enough resolution.
If you have questions write it in the comments. Thanks for reading.