I was able to find a solution, but it was considerably different than what was described above. The critical requirement here is that I am using a combination of Substance Designer and World Machine to generate a high res mesh that *already has a texture set*, i.e. albedo, normal, roughness. The goal is to generate a low…
Colour is easy, most apps will handle that. Normals are harder because they're affected by uv orientation and scaling. In substance designer you can do normals using the texture transfer bake mode. Outside of designer I'm not sure what you can use - you would need to convert the normals to world space, transfer them as…