This Python package exports an animated skeleton (with a skinned mesh) to disk. It's a basic implementation of a UsdSkel exporter. That said, it's mainly for learning purposes and to see how Maya and USD fit together during exporting. This tool will be helpful to 2 types of people:

Someone looking to understand how UsdSkel works with a practical example
Someone who cannot use USD's pre-existing Maya exporter plugin and have to actually write the UsdSkel export process from scratch

If you fall under either camp then you will get a lot out of trying this tool out. But if you aren't learning UsdSkel or aren't expected to re-write an exporter, feel free to skip this project.

Maya Scene Requirements

The DAG graph needs to looks like this
- root (Group node)
  - joints (Joint node)
    - joints1
    - joints2
    - joints3
    - jointsEtc
  - geometry (Group node)
    - mesh1
    - mesh2
    - mesh3
    - meshEtc
- The top-most group that has both the joints and meshes is used as the UsdSkelRoot

There's an example scene file located at example/joints.ma which already has this set up.

To run

Load Maya. (Important: This assumes that Maya's USD plugin is installed correctly)

PYTHONPATH=$PWD/python:$USD_INSTALL_ROOT/python:$PYTHONPATH maya

Open example/joints.ma to get a scene with joints + a bound mesh or create your own
Run this Python code:

from convert_maya_to_usdskel import converter

node = 'root_joint'
converter.write_rig_as_usdskel(
    node, 
    "/SkeletonRoot",
    "/SkeletonAnimation",
    "/tmp/test_export",
)

Disclaimers

This script exports a skeleton definition and animation in a single export command.

In a real pipeline, the command would be split into 2 parts:

A rigger would export the skeleton
An animator would export just the animation

This script exports in a single step to keep the code simple. But most likely, when exporting an animation, you would link to a USD file for the skeleton that already has been written to disk.

Generally speaking, only a basic skeleton could be exported like this.
- Joints with offset groups aren't respected (as well as other more complex rigging features)