Export partial Maya joint hierarchy to USD as Skeleton prims

[NickWu]

Is your feature request related to a problem? Please describe.
Hi, we couldn't find a way to export a subset of Maya joint hierarchy. I know we can use -exportRoots argument to mayaUSDExport command to export a subset of nodes from Maya to USD but this seems not working with joints exporting. When exporting with Maya joints, we need to use -exportSkels otherwise joints won't be exported. This works when you are exporting a whole hierarchy, however, it doesn't work if you just want to export a subset of the hierarchy which requires -exportRoots argument because it would error when using -exportRoots and -exportSkels together. Please see the example below.

Given a hierarchy with a mesh and a joint:

Run the following command to export nodes that are under "parent" and "jointsGrp" group nodes.

cmds.mayaUSDExport(
    f="partialNodes.usda", sl=False, worldspace=True,  stripNamespaces=True,
    exportRoots=("parent", "jointsGrp"), shadingMode="none"
)

If we open the exported file In the usdview, you will see that mayaUSDExport command is able to export nodes that are under "parent", but for node that is under "jointsGrp", it cannot, because it's a Maya joint.

Let's try to export joints with -exportSkels . Run the following code to export joints:

cmds.select("parent", "jointsGrp")
cmds.mayaUSDExport(
    f="joints.usda", sl=True, worldspace=True,  stripNamespaces=True,
    shadingMode="none",
    exportSkels="auto"
)

If you open the exported file in usdview, you will see that joints are exported successfully along with all of its parent nodes:

If we try to use -exportSkels and -exportRoots together to only export the joints under the specified nodes by running the following command:

cmds.select("parent", "jointsGrp")
cmds.mayaUSDExport(
    f="jointsUnderSpecifiedNode.usda", sl=True, worldspace=True,  stripNamespaces=True,
    exportRoots=("parent", "jointsGrp"), 
    shadingMode="none",
    exportSkels="auto"
)

We will get errors saying # Error: RuntimeError: file <string> line 2: Maya command error

Describe the solution you'd like
We'd like to export a subset of nodes that are Maya joints (exclude its parent nodes) under a hierarchy to USD as Skeleton prims. It would be great if -exportSkels argument can work together with -exportRoots argument to achieve this.

Describe alternatives you've considered
If this is not supported currently then I'd like to know if there is a plan to support this in future.

[wallworm]

Thanks for sharing. We will discuss this on the team.

[barbalt]

Closing issue as it has been addressed by #3681

[dilenshah23]

Has this been resolved?