But the question of mine is how useful is this? Will it be ok for ArcViz in Unreal to build the entire ceiling in this way just a texture and a displacement? How the lightmaps baked on it will works? What about the performance of such an approach?
I think because of how extreme the displacement would be on that there would be some issues. What I would do, is make a low poly version of that (might simply be a mesh with the displacement applied at a low subdivision level) and then you could bake normal maps or you could bake small-scale displacement for that low-poly mesh. That would allow the default mesh to have a silhouette that’s much closer to what you want it to be, it should look fine from normal views below if you use that plus normal maps.