You can select a mesh in the viewport and then go to File > Export > Selected Only and choose obj. I think it comes out triangulated this way, but it's something.
Ah ok sorry should have pointed out. So the render is done in marmoset, the result is the same with or without the normal map. And the file format is .Obj
Alright, so now I've got a rough blockout of the level established in Cryengine. Thank god for the solid modeling system. And the ability to export .objs? Nice.
Painter can bake an ID map and one of the options in there is vertex color, which I believe is how polypaint is saved in OBJ files. That should work...