[Isaac Sim] Issue: 3DGS NuReC object does not inherit transform when parented to a Proxy Mesh

[Chauncywu1999]

help!!!!

• 6.0.0
• 5.1.0
• 5.0.0
• 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 24.04
• Ubuntu 22.04
• Ubuntu 20.04
• Windows 11
• Windows 10
• Other (please specify):

GPU Information

• Model: GeForce RTX 5090
• Driver Version: 570.169

Topic Description

3DGS NuReC object does not inherit transform when parented to a Proxy Mesh

Detailed Description

Hi everyone,

I am currently working with NuReC / 3DGS (3D Gaussian Splatting) objects in Isaac Sim and have encountered an issue regarding the scene hierarchy and rigid body transforms.

My Workflow:

1. I have a NuReC 3DGS object in the stage.
2. I created a proxy mesh (to act as a collider/agent).
3. I parented the 3DGS object under the proxy mesh (making the 3DGS object a child of the mesh).
4. I attempted to move the parent proxy mesh.

The Issue: When I move the parent proxy mesh, the 3DGS NuReC object does not follow the movement. Its Xform seems detached from the parent's transformation.

Furthermore, a visual artifact (an unselectable "ghost" target) remains at the original location where the object was first spawned.

Questions:

• Is there a specific constraint or setting required to make 3DGS objects inherit transforms from a parent Xform/Mesh?
• Is the "ghosting" effect a known rendering issue when moving Gaussian Splatting assets?

Steps to Reproduce

1. create a .usdz file

2. set proxy mesh and modify mesh to matte object

3. parented the 3DGS object under the proxy mesh and move it

Screenshots or Videos

Additional Information

What I’ve Tried

I tried grouping both objects under a common Xform, but the issue persists.

[vick-yu]

Hi @Chauncywu1999,

Thank you for the detailed report and the comprehensive screenshots - they really help illustrate the issue you're experiencing with 3DGS NuReC objects and transform inheritance.

I can see that when you parent a 3DGS object under a proxy mesh and move the parent, the 3DGS object isn't following the transform hierarchy as expected, and there's a "ghost" artifact remaining at the original location. This is definitely not the expected behavior for standard USD scene hierarchy.

To help us investigate this further, could you provide some additional information?

1. USD File Structure: Could you share a minimal reproducible .usd/.usdz file?
2. Console Output: Are there any warnings or errors in the Console when you move the parent mesh?
3. Transform Values: When you inspect the 3DGS object's transform properties after moving the parent, do the local transform values change at all, or do they remain static?
4. Version Check: could you also try the same workflow in Isaac Sim 6.0.0 and let us know if the behavior is the same?

Questions about your workflow:

• Does the proxy mesh itself have any physics components (rigid body, collider) applied?
• Have you tried moving the 3DGS object independently (without the parent-child relationship) - does it move correctly in that case?

I'm escalating this to our engineering team to investigate whether this is a known limitation with the 3DGS rendering pipeline or a bug that needs to be addressed. 3DGS/NuReC objects use a specialized rendering path, and there may be constraints on transform inheritance that we need to document or fix.

I'll keep this thread updated as we learn more. In the meantime, if you discover any workarounds, please share them here for other users who might encounter the same issue.

Thanks again for taking the time to document this so thoroughly!