UsdSkel imaging 22.11 VS 23.08


I am in the process of updating the USD version we use in the 3dsMax USD plugin.
I am noticing there must have been some schema change in UsdSkel :

This is the UsdSkel sample, that I had locally (so build in an earlier USD version, I am not quite sure which, most likely 21.X, displayed in 23.08).

Looking at the hydra scene, it seems that some prims are just missing the “skinningComputation” :

Initially i was thinking some regression in USD, as this file showed fine in 22.11, but then re-downloaded the sample from UsdSkel Examples — Universal Scene Description 23.08 documentation , and that version works ok in 23.08

Looking at the release notes, I dont see anything obvious that would explain this (?)

Is this expected? What there a schema change that would prevent older files to no longer work in 23.08?

Many thanks,


I believe I have figured out the problem, by diffing the files as ASCII.

The previous version of the sample didnt have the SkelBindingApi applied on all the prims using usdskel. I guess USD is a bit more strict now…

I think you’re right. I brought up this related issue about another UsdSkel example where Spiff confirms your suspicion.

Relevant snippet from the 23.05 CHANGELOG:

Added compliance tests to make sure UsdSkelBindingAPI is applied on prims having properties provided by UsdSkelBindingAPI. Also added a compliance test to ensure that UsdSkelBindingAPI has only been applied on SkelRoot prims or descendants of SkelRoot prims.

23.08 became strict about requiring SkelBindingAPI to be applied. Note that the updated Skel example on is 100% backwards compatible with earlier releases.