Model: NVIDIA GeForce RTX 5070 Laptop GPU
Driver Version: 592.15
CUDA Version: 13.1
I exported NVIDIA’s built-in iw.hub robot from USD to URDF using Isaac Sim 6.0.1 and then imported the generated URDF back into Isaac Sim.
The original USD looks correct and contains its expected yellow, dark and textured appearance. The export finishes successfully without any error.
However, the re-imported URDF looks incorrect. The robot becomes pale/white, and a very large visible box appears around it. The export settings had “Visualize Collisions” disabled.
I also tested NVIDIA’s built-in UR10e robot. After exporting it to URDF and importing it back, its expected colors were also not displayed correctly and the robot appeared mostly pale.
I expected the re-imported robots to keep their basic appearance and for collision geometry to remain invisible.
Start Isaac Sim 6.0.1 and create a new stage.
Load the built-in NVIDIA iw.hub asset from:
Confirm that the original USD displays its expected colors and textures.
Open File → Export to URDF.
Set Root Prim Path to /World/iw_hub.
Leave “Visualize Collisions” disabled.
Export the robot to a new empty folder.
Import the generated URDF using the default URDF importer settings.
Observe that the robot appears pale/white and a large visible box appears around it.
No error message was reported. The exporter displayed:
Converted USD to URDF:
Export to URDF successful
The screenshots show the original iw.hub USD, the export settings with “Visualize Collisions” disabled, the successful export message, the incorrect re-imported iw.hub, and the additional UR10e result.
iwhub_reproduction_files.zip (1.4 KB)
Exported iw.hub into a new empty folder.
Used the explicit robot root path /World/iw_hub.
Confirmed that “Visualize Collisions” was disabled.
Re-imported the generated URDF using the default importer settings.
Repeated the export and re-import test with NVIDIA’s built-in UR10e asset.
Inspected the generated iw.hub files. The material files reference STL_Robot_albedo.%3CUDIM%3E.png, but no matching texture image was exported.
Found that collision-named box geometry was also included as visible geometry in the generated URDF.
Previous empty robot-name exporter issue, which is fixed in this version:
opened 12:53PM - 12 Jun 26 UTC
closed 07:44PM - 29 Jun 26 UTC
isaac-sim-v6-0-0
isaac-sim-robot-import-export
### Description
## Detailed Description
When exporting a robot USD to URDF usi… ng **File > Export to URDF** in Isaac Sim 6.0.0, the generated URDF file has an empty robot name attribute (`<robot name="">`). This makes the exported URDF invalid, because re-importing it into Isaac Sim fails with a parsing error stating the robot name is required.
I was trying to export Isaac Sim's built-in robot USD assets (e.g. UR3, UR10e) to URDF in order to compare and align them with our own URDF repository. I expected the exported URDF to contain a valid robot name, as it does in Isaac Sim 5.1.0. Instead, the name field is exported empty, and the file cannot be re-imported without manual editing.
The same export workflow in Isaac Sim 5.1.0 correctly populates the robot name (e.g. `<robot name="ur3_usd">`) and the resulting URDF imports without any issue.
## Steps to Reproduce
1. Open Isaac Sim 6.0.0
2. Add a robot from the content browser to the stage (e.g. UR3 from `Isaac/Robots/UniversalRobots`)
3. Delete the fixed 'root/ee_link',`root_joint` (and `ee_joint` if present) so the export proceeds
4. Go to **File > Export to URDF**, set the root prim path, and export
5. Open the exported `.urdf` in a text editor — the `<robot name="">` attribute is empty
6. Attempt to re-import the same URDF via **File > Import** — import fails
## Error Messages
Failed to convert assets ['C:/dev/USD_to_URDF/ur3_isaac6.urdf'] since importer failed with Error parsing XML: robot: name is required (line: 2).
## Environment
- Isaac Sim version: 6.0.0.0 (Full)
- OS: Windows 11
- GPU: NVIDIA RTX 5070 Laptop GPU
## What I've Tried
Manually editing the exported URDF to add a robot name (changing `<robot name="">` to `<robot name="ur3">`) resolves the issue — the URDF then imports successfully. This confirms the only problem is the missing name attribute at export time. The same robot exported from Isaac Sim 5.1.0 includes a valid name automatically.
## Related Issues
Also reported on the developer forum: https://forums.developer.nvidia.com/t/isaac-sim-6-0-0-usd-to-urdf-export-produces-empty-robot-name-attribute-breaks-re-import/373155
## Additional Context
This appears to be a regression in the 6.0.0 USD-to-URDF exporter compared to 5.1.0. The exported joint and link structure is otherwise correct — only the robot name attribute is affected.
### Isaac Sim version
6.0.0
### Operating System (OS)
Windows 11
### GPU Name
RTX 5070
### GPU Driver and CUDA versions
Driver 591.74
### Logs
Failed to convert assets ['C:/dev/USD_to_URDF/ur3_isaac6.urdf'] since importer failed with Error parsing XML: robot: name is required (line: 2).
### Additional information
_No response_
Open USD-to-URDF scaling issue, which may be related to the oversized box:
opened 03:43PM - 12 Jun 26 UTC
isaac-sim-v6-0-0
isaac-sim-robot-import-export
### Description
Follow-up of #657
In Isaac Sim 6.0.0 GA, the URDF export does … not correctly apply scaling to the entire robot hierarchy. Only the meshes of the first robot link in the exported URDF receive the scaling factor, while all subsequent meshes remain unscaled.
**Reproduction steps:**
1. Create a new stage and add a ground plane.
2. Open the Content Browser and drag any robot into the scene at the viewport's origin (might only apply to manipulators/grippers; I have used `so101_new_calib`).
3. Select the robot's parent Xform (`so101_new_calib`) and change its scale from `(1.0, 1.0, 1.0)` to `(0.1, 0.1, 0.1)` in the *Properties* panel.
4. Noticed that the whole robot has been scaled correctly in the viewport of the Isaac Sim UI
5. Export the robot as URDF via **File** -> **Export to URDF** as `so101_new_calib.urdf`.
6. Open the generated URDF file in a code editor (e.g., VS Code).
7. See in the code the URDF file that only the meshes of the first robot link (`base`) contain the scaling attribute (`scale="0.1 0.1 0.1"`). All subsequent links have been remained untouched and their meshes have been exported without the applied scale.
Same scaling issue applies in the URDF exported file when importing a robot that uses `scale:unitsResolve` parameter.
### Isaac Sim version
6.0.0 GA
### Operating System (OS)
Windows 11
### GPU Name
RTX 3080 Ti
### GPU Driver and CUDA versions
GameReady 591.86, CUDA 13.3
### Logs
_No response_
### Additional information
_No response_
Older report about oversized dimensions after USD-to-URDF conversion:
URDF Viewer Example ) webpage, all the dimensions of the robot are really large. looks like all the units of measurement have been swit…
The generated iw.hub URDF contains a valid robot name, so the earlier empty-name problem is no longer present.
The export generated 8 OBJ files and 8 MTL files, but no PNG or JPG texture files. All 8 MTL files reference the same missing UDIM texture.
I have attached a small ZIP containing the generated URDF and one example MTL file.
GitHub tracking issue:
opened 11:26PM - 18 Jul 26 UTC
### Description
Exporting NVIDIA’s built-in iw.hub robot from USD to URDF compl… etes 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
1. Start Isaac Sim 6.0.1 and create a new stage.
2. Load `Isaac/6.0/Isaac/Robots/Idealworks/iwhub/iw_hub.usd`.
3. Open **File → Export to URDF**.
4. Set **Root Prim Path** to `/World/iw_hub`.
5. Leave **Visualize Collisions** disabled.
6. Export to a new empty folder.
7. Import the generated URDF using the default importer settings.
8. 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
<img width="2529" height="178" alt="Image" src="https://github.com/user-attachments/assets/12972434-dbb5-4e53-b29a-6d9d49b58a35" />
### Additional information
### Generated-file findings
The generated iw.hub URDF contains a valid robot name:
```xml
<robot name="iw_hub">
```
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:
```xml
<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:
```text
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
- #668 — previous empty robot-name exporter problem, fixed in this build.
- #670 — incomplete USD-to-URDF scaling, possibly related to the oversized boxes.
### 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.
<img width="2548" height="1222" alt="Image" src="https://github.com/user-attachments/assets/a46795a8-037b-4933-abf1-204d56bacbdb" />
<img width="1530" height="833" alt="Image" src="https://github.com/user-attachments/assets/1371c6e4-6eb1-4b90-83a7-abb7927f3f88" />
<img width="2530" height="1035" alt="Image" src="https://github.com/user-attachments/assets/5b32fe23-2d25-496e-b5ed-ea028d4f3f76" />
[iwhub_reproduction_files.zip](https://github.com/user-attachments/files/30158352/iwhub_reproduction_files.zip)
<img width="2438" height="974" alt="Image" src="https://github.com/user-attachments/assets/f76f172c-773f-48e3-8a06-7e9dfaa86dc9" />
