FBX → USD Conversion Not Preserving Skeleton/Rigging

Omniverse Isaac Sim
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Isaac Sim Version

5.1.0

Operating System

Ubuntu 22.04

FBX → USD Conversion Not Preserving Skeleton/Rigging

Detailed Description

I am trying to convert an FBX file to USD for use in IsaacSim using the Asset Converter. While the USD file shows a skeleton with all joints in the raw USD data, IsaacSim does not recognize the joints correctly. Attempts to wrap the skeleton with a SkelRoot using UsdSkel and bind it to the mesh do not resolve the issue.

Exporting the same FBX in Blender shows the skeleton correctly, and both FBX and USD show correct rigging in Unity, but importing into IsaacSim still fails to register the rig properly. Adding animation before export did not help.

It seems the problem may be with IsaacSim’s USD skeleton import rather than the conversion process itself.

Steps to Reproduce

  1. Convert an FBX with skeleton/rigging to USD using Asset Converter in IsaacSim.

  2. Inspect the resulting USD file; skeleton and joints are present in raw data (observed in Unity software)

  3. Import USD into IsaacSim.

  4. Observe that the mesh does not recognize the joints properly.

  5. Optional: Attempt to manually wrap the skeleton using UsdSkel API – this does not fix the issue.

Error Messages

No explicit error messages; skeleton appears in USD but joints are not recognized by IsaacSim.

Additional Information

What I’ve Tried

  1. Used Asset Converter with default settings (embed textures, convert Z-up, ignore materials False).
  2. Tried manually creating SkelRoot and UsdSkel.Skeleton in Python and binding it to the mesh.
  3. Verified that Blender imports FBX skeleton correctly.
  4. Exported USD from Unity with skeleton and animation; still not recognized in IsaacSim.
  5. Checked forums for similar issues; wrapping skeleton under SkelRoot is suggested but does not solve it.
2

@damitasg i am just another user, but i was wondering if you’ve tried exporting as USD directly from Blender and whether the result behaves the same way?

3

Hello!

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