I used Sculptfab to create/sculpt a mesh, then saved it and imported it into UE. I got a warning “myMesh has degenerate tangent bases which will result in incorrect shading.” And it was true, I could see black “artifacts” in many places on the object when viewed in UE (mostly around sharper edges and stretched surfaces I think).
I realize this might be also related to Sculptfab itself, but I’d rather think that something can be improved regarding the importing process in UE.
Furthermore, in the log I saw two other messages (probably less of a problem):
No smoothing group information was found in this FBX scene…
The imported mesh is very small. This is most likely an issue with the units used when exporting to FBX…
The file format is OBJ. (The sculpting tool also supports PLY and STL, but I don’t think UE does.)
Sculptfab: SculptFab - SculptGL + Sketchfab
The degenerate tangent issue is a UV. Since Sculptfab has no UV tools you’ll more than likely get degenerate tangents due to these not being setup properly from a modeling application. In 4.8 in the Static Mesh Editor > Build Settings there will be an option to disable MikkTSpace to ignore degenerate tangents issues, but this can still cause shading issues with the mesh, since this is just ignoring the issue mostly.
The artifacts are the shading issues from the degenerate tangents and the mesh not being scaled to a large enough size. You can scale the mesh on import by adjusting the build scale or using the Build settings in the static mesh editor to do this on the XYZ.
While sketchfab is a good solution for quickly sculpting a mesh it will need to be finalized and setup properly in a modeling application.