Broken USD rotation animations due to discontinuous Euler values

[TheRealANDREWQA]

Describe the bug
Maya USD animation imports can have discontinuous rotations, where the euler rotation suddenly jumps to a different non-continuous value. This can happen from meshes exported by other tools, but also in Maya FBX -> USD conversions.

Steps to reproduce
Steps to reproduce the behavior:

1. Import the attached mesh "Bot Silly Dancing.fbx" (enable animations)
2. Group the 3 top levels nodes and then click export, then select USD as format and include animations
3. Clear the scene by deleting the top-level node
4. Import the converted USD (enable animations)
5. Run the animation at a high fps rate (~500fps) where the left shoulder will do some unnatural movements

Expected behavior
The animation in the imported USD should behave identical to the one from the FBX format.

Attachments
Problematic mesh (it is in the .zip archive), a video showcasing the issue, one screenshot is with the animation curves of the FBX mesh (the first image), while the second one is the same mesh exported with a different tool and imported into Maya as USD, showcasing the discontinuous Euler rotations.

Specs (if applicable):

• OS & version: Windows 10
• Compiler & version: Not compiled from source
• Maya version: Maya 2025.3

Additional context
A clue might be the following function, UsdSkelDecomposeTransform, provided by the Pixar's USD SDK. Since it decomposes a matrix into TRS, the quaternion that it returns might not necessarily be in the same neighborhood as the previous one. I have seen this myself for a USDA file where I knew for a fact that the quaternion rotation at a time sample was [0.622, 0.312, 0.199, -0.689], meanwhile the quaternion that the decomposition returned was [-0.622, -0.312, -0.199, 0.689]. Depending on how the conversion to Euler is done afterwards, it might make the rotation values be discontinuous, when in fact they should be continuous.
In the provided test mesh, the problem manifests itself at high fps rates and not at smaller ones, because the intermediary samples don't fall into the discontinuities and jump over them, but for some other meshes exported by other tools, this can happen at many fps rates, including low and high.

2025-07-30.13-21-40.mp4

Bot Silly Dancing.zip

[barbalt]

Hello @TheRealANDREWQA ,
Thanks for creating this issue.

As you already pointed out, this is an issue due to the euler rotation. There's an option when importing a file with python to apply euler filter during import. I've tested the option and the issue no longer occurs.

Here's the simple script that I used for this example:

from maya import cmds

cmds.file(f=1, new=1)
cmds.mayaUSDImport(file="[fullpathhere]/Bot.Silly.Dancing/bot.silly.dancing.usd", ani=1, aef=1)

The aef=1 is the required flag for applyEulerFilter. This makes the creating of the rotation to check the previous one to get the closest angle.

Sadly this option is not available on the import UI. We'll create a ticket internally to facilitate the process when using the ui. Meanwhile, if possible, please refer to the script above to fix your current issue.

[TheRealANDREWQA]

Thank you for the helpful information and for providing the script. However, the script doesn't quite address our needs, as we're developing a 3D software application that exports USD mesh files. These files are then imported into Maya by our non-technical users, who rely exclusively on the UI for their workflows. With the current import options in Maya, they often assume the mesh is faulty—despite it being exported correctly—which creates confusion. That's why a dedicated UI option, such as a checkbox during import, is what we need. It would make it much easier to guide our users through the process compared to instructing them on running a custom script. Could you provide an estimation regarding how long the UI option will take to be implemented?

[barbalt]

Hi @TheRealANDREWQA,
I'm sorry, but I can't give an estimation when this task will be completed.

[barbalt]

Hi @TheRealANDREWQA I'm closing this ticket as the PR #4327 has solved the issue. If you have are able to locally build maya-usd, you can give that a try. Thanks for reporting once again