Usd Skeleton export with 'unit' flag still broken

[paulgolter]

Maya USD skeleton export is still broken when using the unit flag to export at meter scale.

I added a MetaHuman test scene to this ticket. You can open it without any plugins except Maya USD 0.36.0_202604211024-04a277d, of course.

This bug was reported before and marked as "closed", but it still exists: #4377

In the video you can see first a regular export without using the unit flag, which works as expected.

The second export is using the unit flag, which results in a usd file with a completely scrambled character / usd skeleton.

2026-06-17.11-53-49.mp4

To reproduce

• Open the Maya scene attached to this ticket.
• Select the rig group and its hierarchy.
• Export the selection as USD.
• Enable skeleton export:
  • Skeleton: All
  • Skin Clusters: All
  • Blend Shapes
  • Under "Advanced", set the unit flag to meter.

Maya Scene

maya_usd_scale_export_bug.zip

Specs

• Windows 11
• Maya 2025
• Maya USD 0.36.0_202604211024-04a277d

[paulgolter]

I dug into the maya-usd source and found the cause: when exporting with the unit flag, the skeleton's bind and rest matrices get scaled entirely (rotation included) instead of just their position part. Everything else in the file converts correctly, and that mismatch is what makes the skinned geo explode.

I've opened a fix: #4686

Workaround until the fix ships:
Broken matrices are easy to spot (their last value is the unit factor instead of 1), so the little export chaser below repairs them right before the file is written. It's safe to leave on permanently — on a fixed maya-usd build it simply does nothing.

skel_unit_fix_chaser.py