URDF Export Error: "Joint transforms are not consistent"

Omniverse Isaac Sim
1

Isaac Sim Version

4.5.0
4.2.0
4.1.0
4.0.0
4.5.0
2023.1.1
2023.1.0-hotfix.1
Other (please specify):

Operating System

Ubuntu 22.04
Ubuntu 20.04
Windows 11
Windows 10
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Topic Description

Hi all,

I’m encountering a URDF export error in Isaac Sim when trying to export a hand model. The error message says the joint transforms of right_wrist are not consistent.

Error Messages

2025-05-26 00:42:38 [1,278,323ms] [Error] [omni.ui.python] ValueError: The ‘right_wrist’'s joint transforms are not consistent.
global___joint_via_parent:
[[ 0.99991778 -0.00107529 0.01277769 0.01262659]
[ 0.00121027 0.9999435 -0.01056059 -0.00192864]
[-0.01276562 0.01057519 0.99986259 0.15084681]
[ 0. 0. 0. 1. ]]
global___joint_via_child:
[[ 0.99991778 -0.00167431 0.01271308 0.01262657]
[ 0.00121028 0.99933581 0.03642067 -0.00192864]
[-0.01276562 -0.03640229 0.99925568 0.15084675]
[ 0. 0. 0. 1. ]]

At:
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(816): _update_joint_node
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(686): _build_transform_graph
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(340): init_from_stage
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/to_urdf.py(74): init
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.asset.exporter.urdf/isaacsim/asset/exporter/urdf/ui_builder.py(267): _on_export_button_clicked_fn
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/exts/isaacsim.gui.components/isaacsim/gui/components/element_wrappers/ui_widget_wrappers.py(886): _on_clicked_fn_wrapper
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/omni/kit_app.py(128): update
/home/tao/miniconda3/envs/isaaclab45/lib/python3.10/site-packages/isaacsim/init.py(163): main
/home/tao/miniconda3/envs/isaaclab45/bin/isaacsim(8):

Additional Context

hand14.usd.zip (1.4 MB)

3

I saw similar error message with a different joint:

2025-06-02 22:07:38 [57,892,691ms] [Error] [omni.ui.python] ValueError: The 'right_index_abd''s joint transforms are not consistent.
global___joint_via_parent:
[[-0.41460916  0.90705789  0.07311108 -0.01209444]
 [-0.00251902 -0.08148557  0.99667134 -0.00988924]
 [ 0.9099961   0.41304489  0.03606956  0.21462987]
 [ 0.          0.          0.          1.        ]]
global___joint_via_child:
[[-0.41186366  0.90830784  0.07311079 -0.01209442]
 [-0.00276544 -0.08147724  0.99667137 -0.00988923]
 [ 0.91124129  0.41029053  0.03606939  0.21462987]
 [ 0.          0.          0.          1.        ]]

At:
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(816): _update_joint_node
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(686): _build_transform_graph
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/transform_graph.py(340): init_from_stage
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/to_urdf.py(74): __init__
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/pip_prebundle/nvidia/srl/from_usd/to_urdf.py(129): init_from_file
  /home/vyu/isaacsim/exts/isaacsim.asset.exporter.urdf/isaacsim/asset/exporter/urdf/ui_builder.py(270): _on_export_button_clicked_fn
  /home/vyu/isaacsim/exts/isaacsim.gui.components/isaacsim/gui/components/element_wrappers/ui_widget_wrappers.py(886): _on_clicked_fn_wrapper

This issue is often related to how the joints are defined in the original .usd file, especially if the relative transforms between connected bodies are not set up correctly. Please check the joint origins in your .usd file and ensure that the transforms for each joint are consistent and correctly positioned relative to the connected bodies.

4

Hello!

We noticed that this topic hasn’t received any recent responses, so we are closing it for now to help keep the forum organized.

If you’re still experiencing this issue or have additional questions, please feel free to create a new topic with updated details. When doing so, we recommend mentioning or linking to this original topic in your new post—this helps provide context and makes it easier for others to assist you.

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Best regards,

The NVIDIA Isaac Sim Forum Team