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Nested abc/usd standin within usd standin does not apply transform in viewport correctly

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jrosenA9TLN
293 Views, 1 Reply

Nested abc/usd standin within usd standin does not apply transform in viewport correctly

Maya 2020.4
MtoA 4.2.3
Arnold Core 6.2.1.1

I'm trying to setup a nested standin/reference workflow using abc and usd (alembic doesn't support exporting/expanding arnold standins). But I've noticed when I export my geometry as .abc the geometry doesn't have the transforms applied.

+ standin --> (cube_group.usda) + group
                                  + standin --> cube.abc

Repro:

  • Select and export cube at origin: Arnold --> Scene Export -> Export Selection to Alembic... (Use defaults)
  • Create Standin
  • Set Path to exported .abc file
  • Group and set transform to 1, 1, 1
    screen-shot-2021-08-12-at-103233-am.png
  • Select and export group1: Arnold --> Scene Export -> Export Selection to Usd...
  • Under Export section uncheck everything except Shapes and Shaders (Unchecking Full Paths didn't seem to have an affect)
  • Create Standin
  • Set path to exported .usd, cube appears at the origin
    screen-shot-2021-08-12-at-103754-am.png
    def ArnoldAlembic "pCube1StandinShape"
    {
        string arnold:filename = ".../maya/arnold_forum/abc_cube_viewport/cube.abc"
        string arnold:name = "pCube1StandinShape"
        float arnold:radius_default = 0.01
        float3[] extent = [(-0.5, -0.5, -0.5), (0.5, 0.5, 0.5)]
        string primvars:dcc_name = "pCube1StandinShape" (
            elementSize = 1
            interpolation = "constant"
        )
        string primvars:maya_full_name = "|group1|pCube1Standin|pCube1StandinShape" (
            elementSize = 1
            interpolation = "constant"
        )
        matrix4d xformOp:transform.timeSamples = {
            0: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (1, 1, 1, 1) ),
        }
        uniform token[] xformOpOrder = ["xformOp:transform"]
    }
  • But renders correctly
    screen-shot-2021-08-12-at-105724-am.png
  • Repeat the above steps to export the cube as a .usda, create a standin, group and export as .usda
  • The geometry is now double transformed
    screen-shot-2021-08-12-at-105349-am.png
    def Xform "group2"
    {
        def Xform "pCube1_usd"
        {
            def ArnoldUsd "pCube1_usdShape"
            {
                string arnold:filename = ".../maya/arnold_forum/abc_cube_viewport/cube.usda"
                float3[] extent = [(-0.5, -0.5, -0.5), (0.5, 0.5, 0.5)]
                string primvars:dcc_name = "pCube1_usdShape" (
                    elementSize = 1
                    interpolation = "constant"
                )
                matrix4d xformOp:transform.timeSamples = {
                    0: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (1, 1, 1, 1) ),
                }
                uniform token[] xformOpOrder = ["xformOp:transform"]
            }
        }
    }
  • But renders correctly (minus shading - diff issue)
    screen-shot-2021-08-12-at-105724-am.png

I thought this was fixed with MtoA 4.2.2 - Nested procedurals ignore matrix in viewport API #508, but it looks like there's still issues.

I can add zip of my file if that's useful. But I couldn't get relative paths with Arnold Scene Export to work.

Labels (4)
1 REPLY 1
Message 2 of 2
Stephen.Blair
in reply to: jrosenA9TLN

I can repro, thanks for reporting.

I'll post the ticket number after I log it...

Update: This is logged as MTOA-729



// Stephen Blair
// Arnold Renderer Support

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