[EMSUSD-2544] Animation Rotation Mismatch After USD to Maya Data Conversion

[liang256]

Describe the bug
When importing a SkelAnimation using Maya’s native USD plugin and converting the skeleton to Maya data via “Duplicate as Maya Data” (or similar operation), the resulting joint rotations during the animation do not match the original USD animation. The pose at the start and end frames is correct, but the interpolated poses in-between deviate from the expected result.

In the recording, the white geometry represents the original USD data, while the gray one is the duplicated ArmRig converted to Maya data, which shows the twisted animation.

rotation_mismatch.mov

Steps to reproduce

1. In Maya, go to Create → Universal Scene Description (USD) → Stage from File… and select the attached arm_rig_anim.usda file.
2. Right-click on the SkelRoot or Skeleton node and choose “Duplicate as Maya Data”.
3. Scrub the timeline between frame 1 and 24.
4. Observe the joint rotations in Maya.

Expected behavior
The animation in Maya should match the SkelAnimation stored in the USD file. The rotation interpolation, especially between frames, should remain consistent.

Attachments
arm_rig_anim.usda – A minimal SkelAnimation example using quaternion rotations that clearly demonstrates the mismatch between USD and Maya animation playback.

#usda 1.0
(
    defaultPrim = "ArmRig"
    startTimeCode = 1
    endTimeCode = 24
    upAxis = "Y"
    metersPerUnit = 0.01
)

def SkelRoot "ArmRig" (
    kind = "component"
    prepend apiSchemas = ["SkelBindingAPI"]
)
{
    def Skeleton "Skeleton" (
        prepend apiSchemas = ["SkelBindingAPI"]
    )
    {
        uniform token[] joints = ["Shoulder", "Shoulder/Elbow", "Shoulder/Elbow/Hand"]

        uniform matrix4d[] bindTransforms = [
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,0,1)),
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,2,1)),
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,4,1))
        ]

        uniform matrix4d[] restTransforms = [
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,0,1)),
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,2,1)),
            ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,2,1))
        ]

        def SkelAnimation "Anim"
        {
            uniform token[] joints = ["Shoulder", "Shoulder/Elbow"]

            float3[] translations = [(0, 0, 0), (0, 0, 2)]
            quatf[] rotations.timeSamples = {
                1:  [(1, 0, 0, 0), (1, 0, 0, 0)],
                24: [(0, 0, 1, 0), (0.7071, 0.7071, 0, 0)]
            }
            half3[] scales = [(1,1,1), (1,1,1)]
        }

        rel skel:animationSource = </ArmRig/Skeleton/Anim>
    }

    def Mesh "ArmMesh" (
        prepend apiSchemas = ["SkelBindingAPI"]
    )
    {
        rel skel:skeleton = </ArmRig/Skeleton>

        point3f[] points = [
            (0.5, -0.5, 4), (-0.5, -0.5, 4), (0.5, 0.5, 4), (-0.5, 0.5, 4),
            (-0.5, -0.5, 0), (0.5, -0.5, 0), (-0.5, 0.5, 0), (0.5, 0.5, 0),
            (-0.5, 0.5, 2), (0.5, 0.5, 2), (0.5, -0.5, 2), (-0.5, -0.5, 2)
        ]

        int[] faceVertexCounts = [4, 4, 4, 4, 4, 4, 4, 4, 4, 4]
        int[] faceVertexIndices = [
            2, 3, 1, 0,
            6, 7, 5, 4,
            8, 9, 7, 6,
            3, 2, 9, 8,
            10, 11, 4, 5,
            0, 1, 11, 10,
            7, 9, 10, 5,
            9, 2, 0, 10,
            3, 8, 11, 1,
            8, 6, 4, 11
        ]

        int[] primvars:skel:jointIndices = [
            2, 2, 2, 2,
            0, 0, 0, 0,
            1, 1, 1, 1
        ] (
            interpolation = "vertex"
            elementSize = 1
        )

        float[] primvars:skel:jointWeights = [
            1, 1, 1, 1,
            1, 1, 1, 1,
            1, 1, 1, 1
        ] (
            interpolation = "vertex"
            elementSize = 1
        )

        matrix4d primvars:skel:geomBindTransform = ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,0,1))
    }
}

Specs

• OS & version: macOS Sonoma 14.5
• Maya version: Maya 2025.3

Additional context

• Applying Euler filters within Maya can smooth the result.
• Ensuring correct quaternion to Euler conversion (and interpolation) may be the core fix.
• This issue affects the accuracy of round-tripping animation data between DCCs.

[wallworm]

Thank you for sharing with us. We will investigate.

[santosd]

Hi @liang256, I took a look at this and was able to repro the issue in the latest internal version that I have of MayaUSD and Maya. Unfortunately I was not able to find a workaround for the issue. However, I am having a dev take a look at the issue to see if we can find a solution to the problem. Thank you for reporting this.

[liang-cheehoo]

Hi @santosg87 , thanks for confirming the issue and for having a dev take a look. Let me know if you need any additional info from my end. Appreciate the follow up!

[barbalt]

Hi @liang256 , thanks for opening issue.

There are two issues being described here:

• The rotation not going into proper direction can be addressed using the applyEulerFilter. When converting to maya, the object has the correct initial and final rotations, however, we can't guarantee the correct rotation on the frames interpolated. That flag makes it so that we use the previous rotation to calculate the next one (among other things) which can fix the issue for this case.
• The second problem is that, when creating the key frames in maya curves, we were setting the keys with curved tangents. USD, however, interpolate the frames using a linear interpolation. So I've opened a pr to correctly apply the linear keys when importing (duplicating) a usd file.

Thanks