Datasmith exporter produces more than 64 materials per mesh which is the limit for Nanite

Question

Using CityEngine 2022.1

Hi team. We are exporting large number of 3D photogrammetry generated buildings using the Datasmith exporter with the following settings:

Mesh Merging: GLOBALLY

Use Texture Atlases: True

The results are large integrated meshes (desired) with a reduced number of textures due to texture atlasing. The issue lies in the fact that some of these meshes have more than 64 materials instances assigned to them, which is erroring when importing into Unreal specifically when converting to Nanite. It seems like Nanite has a limit of 64 materials per mesh.

Is there any way to combine meshes with a limit of 64 materials? How do you suggest we do this in CityEngine before exporting?

Thank you!

BenjaminNeukom · Answer

Hi Gabi!

Currently there is no way to do that with our exporter.

But what you could try is exporting them using mesh merging set to "globally by material" without texture atlassing and then enabling Nanite on each mesh.

The good thing about Nanite is that many meshes won't impact performance as they are rendered using a different render pass from the normal geometry.

Let me know if that works for you!

Best,

Benjamin