Description
Exporting NVIDIA’s built-in iw.hub robot from USD to URDF completes successfully, but importing the generated URDF back into Isaac Sim produces an incorrect result.
The original USD has its expected yellow, dark and textured appearance. After the round trip, the robot becomes pale/white and large collision boxes are rendered as visible geometry, even though Visualize Collisions was disabled during export.
Steps to reproduce
- Start Isaac Sim 6.0.1 and create a new stage.
- Load
Isaac/6.0/Isaac/Robots/Idealworks/iwhub/iw_hub.usd.
- Open File → Export to URDF.
- Set Root Prim Path to
/World/iw_hub.
- Leave Visualize Collisions disabled.
- Export to a new empty folder.
- Import the generated URDF using the default importer settings.
- Observe the pale robot and large visible boxes.
Expected result
The supported visual appearance should be preserved, and collision-only geometry should remain non-rendered.
Actual result
The generated URDF includes collision-named boxes as both visual and collision geometry. Its material files also reference a texture that is not included in the export.
The same incorrect pale appearance was also observed after exporting and re-importing NVIDIA’s built-in UR10e asset.
Isaac Sim version
6.0.1-rc.7
Operating System (OS)
Windows 11
GPU Name
RTX 5070
GPU Driver and CUDA versions
Driver 592.15, CUDA 13.1
Logs
No error was reported. The exporter completed successfully:
Converted USD to URDF:
D:/isaac_urdf_material_results/iwhub_ticket_reproduction/iwhub_ticket_reproduction.urdf
Export to URDF successful
Additional information
Generated-file findings
The generated iw.hub URDF contains a valid robot name:
This confirms that the earlier empty robot-name problem reported in #668 is fixed in this build.
However, collision-named boxes are written under both <visual> and <collision>. For example:
<visual name="Collision">
<geometry>
<box size="0.99999998 0.99999998 0.99999998"/>
</geometry>
</visual>
<collision name="Collision">
<geometry>
<box size="0.99999998 0.99999998 0.99999998"/>
</geometry>
</collision>This occurs even though Visualize Collisions was disabled during export.
The export contains:
- 8 OBJ files
- 8 MTL files
- No PNG or JPG texture files
All eight MTL files reference:
map_Kd STL_Robot_albedo.%3CUDIM%3E.png
No matching texture was written to the export directory.
Additional UR10e test
I also exported and re-imported NVIDIA’s built-in UR10e asset. Its generated MTL files contain the expected named colours, but collision mesh files are also included as visual geometry. The re-imported UR10e consequently appears predominantly pale.
Forum report
https://forums.developer.nvidia.com/t/isaac-sim-6-0-1-usd-to-urdf-export-causes-missing-colors-and-large-visible-collision-boxes/377373
Related issues
Attachments
Screenshots show the original iw.hub USD, export settings, incorrect re-imported iw.hub and the additional UR10e result. The ZIP contains the generated iw.hub URDF and one example MTL file.
[iwhub_reproduction_files.zip](https://github.com/user-attachments/files/30158352/iwhub_reproduction_files.zip)
Description
Exporting NVIDIA’s built-in iw.hub robot from USD to URDF completes successfully, but importing the generated URDF back into Isaac Sim produces an incorrect result.
The original USD has its expected yellow, dark and textured appearance. After the round trip, the robot becomes pale/white and large collision boxes are rendered as visible geometry, even though Visualize Collisions was disabled during export.
Steps to reproduce
Isaac/6.0/Isaac/Robots/Idealworks/iwhub/iw_hub.usd./World/iw_hub.Expected result
The supported visual appearance should be preserved, and collision-only geometry should remain non-rendered.
Actual result
The generated URDF includes collision-named boxes as both visual and collision geometry. Its material files also reference a texture that is not included in the export.
The same incorrect pale appearance was also observed after exporting and re-importing NVIDIA’s built-in UR10e asset.
Isaac Sim version
6.0.1-rc.7
Operating System (OS)
Windows 11
GPU Name
RTX 5070
GPU Driver and CUDA versions
Driver 592.15, CUDA 13.1
Logs
No error was reported. The exporter completed successfully:
Converted USD to URDF:
D:/isaac_urdf_material_results/iwhub_ticket_reproduction/iwhub_ticket_reproduction.urdf
Export to URDF successful
Additional information
Generated-file findings
The generated iw.hub URDF contains a valid robot name:
This confirms that the earlier empty robot-name problem reported in #668 is fixed in this build.
However, collision-named boxes are written under both
<visual>and<collision>. For example:This occurs even though Visualize Collisions was disabled during export.
The export contains:
All eight MTL files reference:
No matching texture was written to the export directory.
Additional UR10e test
I also exported and re-imported NVIDIA’s built-in UR10e asset. Its generated MTL files contain the expected named colours, but collision mesh files are also included as visual geometry. The re-imported UR10e consequently appears predominantly pale.
Forum report
https://forums.developer.nvidia.com/t/isaac-sim-6-0-1-usd-to-urdf-export-causes-missing-colors-and-large-visible-collision-boxes/377373
Related issues
Attachments
Screenshots show the original iw.hub USD, export settings, incorrect re-imported iw.hub and the additional UR10e result. The ZIP contains the generated iw.hub URDF and one example MTL file.