Exporting meshes causes UV unwelding

Hi guys,
I’m facing a weird issue exporting meshes in Rhino Version 5 SR14 64-bit
(5.14.522.8390, 22/05/2017).

These are the steps:

  • Exporting joined surfaces from Rhino as obj mesh,
  • UV Mapping with an external software (all the seams are perfectly welded) and exporting an OBJ file,
  • Importing new OBJ in Rhino,
  • Selecting and re-exporting this mesh from Rhino as OBJ.

When I import this new OBJ in the same UV mapping software used before it’s shows me that all the faces are unwelded forcing me to redo all the UV mapping work.

Thanks for help

These are my OBJ Export Options:

Hello - so it looks like the trouble occurs at step four, correct? The initial export is correct but the second one is not? Can you post an example that shows the problem?


Yes i think so.

I’m uploading an example.1.zip (816.9 KB)

This shape was previously exported from Rhino than UV Mapped inside Maya LT, everything’s fine here. As you can see down below all the vertex are welded inside UV Editor.

Once I’ve completed the UV Mapping task I just export as OBJ this mesh and double check if everything it’s welded using another software (the orange lines are the borders).

I’m importing this OBJ inside Rhino with these settings:

When I export this same shape from Rhino and import in Maya the vertex in the UV map are all unwelded:

Double check in the other software (borders in orange):

Thanks for helping!

Hello - is the file you posted from Rhino? If so, can you also post the one direct from Maya?


no, is exported from Maya.

This is the same OBJ but exported from Rhino (unwelded): 1-RHINO.zip (1.2 MB)


Hi Julio - the mesh is unwelded from Maya then… I don’t think there is anything Rhino can do about that other than to Weld yourself.


Thanks for helping Pascal.

It’s weird because before importing in Rhino I’m double checking with RizomLab UV Editor, and it’s all good.

When I import the Maya-mapped object into Blender and check the UVs all faces are separate (unwelded).

Here I selected and moved one UV-face


nvm - it appears to be an import setting - if I import without splitting on groups and objects the UV imports fine in Blender (from 1.zip).