FBX export unwelds mesh, loses sharp edges and ruins UVs

Hi,

I am experiencing what appears to be a very bad bug detrimental to my company’s day to day pipeline.

When exporting from Rhino 7, typically we would export as an .OBJ as that is the only way to produce a welded mesh from Rhino that retains edge sharpness, however we have ran into problems explained in this forum post so are instead trying to export as .FBX

However the mesh produced in the .FBX is not welded and there is no option to weld meshes on export like there is when exporting as .OBJ making models extremely difficult to work with.

Fixing this introduces very cumbersome and additional steps that are just not feasible for models with hundreds or thousands of parts that we typically work with. This is not a simple case of welding the mesh in Rhino as doing this loses edge sharpness and, to reiterate, is an extra step that we otherwise would not have to do.

Resulting .FBX files also seem to obscure UVs, ignoring their scale and position.


here is my desired geometry in rhino. notice the selected mesh is a closed mesh


here are the settings used to export as .FBX


here is the resulting .FBX in blender. the shells are one object but are unwelded and the UV scaling and position is completely wrong in comparison to the rhino geometry.

I ran into the same issue and a few more, see: How to properly export/import meshes and SubDs with texture coordinates? - Rhino - McNeel Forum

Unfortunately I don’t have a solution yet. As far as I can tell, part of the issue is the way Rhino stores UV values internally. There are cases, where a second “render mesh” is created, that is used to handle split UVs. That’s likely the cause for difference in UVs between Rhino and blender.

Hi @andyconnacher ,

Try using the ExtractRenderMesh command on your model in Rhino after the UVs are as you want and then use the Export command to save that mesh only as FBX for transfer.

Hi Brian,

Still getting unwelding issues when exporting the extracted render mesh.

Here’s an example of the sort of files i’m using

teset34.3dm (5.5 MB)
teset34.fbx (41.2 KB)

Hi @andyconnacher ,

I’m not seeing a difference in the UVs of the render mesh in Rhino and the FBX I saved there once in Blender…

Your FBX file appears the same as mine too. Can you show the specific area that doesn’t match in the UVs due to edge welding?