USD containing particle system behaves strangely when spawned in environment

[cxh3941]

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
Other (please specify): Ubuntu 24.04.2 LTS

Topic Description

Hi, I have a USD file of a particle system that is supposed to behave like this (drop into a clump):

However, when I spawn it in a more complex environment with the spawner cfg like so,

cfg = sim_utils.UsdFileCfg(usd_path=path) 
cfg.mass_props = sim_utils.MassPropertiesCfg(density=density) # the same density as original file

the particles explode immediately after the GUI loads:

The particle system is not initially touching anything else and all of the parameters are the same upon inspection. What could be some things causing this behaviour? Pointers in the right direction are greatly appreciated!

[michalin]

Hi @cxh3941, thanks for posting this question. I will look into this strange behavior promptly.

Michael

[michalin]

Actually, for me to more quickly debug this, could you share the scripts and/or usd to replicate this behavior?

[cxh3941]

Hi Michael, thanks so much for the response. I found my issue actually: we had a function that changed the scale of the imported USDs in the manager-based environment. I believe the particles were exploding because they ended up being touching after that scaling.

Following up on particles with a different question though, I have been using this workaround to render the animations in the GUI for different workflows with particles:

world = World(backend="torch", device="cpu")
physx_interface = acquire_physx_interface()
physx_interface.overwrite_gpu_setting(1)

Spawning particles using <UsdGeom.Points> throws an error about how the world must be initialized with GPU, but then I am unable to see the animations. Has the rendering issue been resolved or do you know of any future fixes? Thanks again.

[michalin]

It great that you found a fix. Would you mind sharing your script to see how you are unable to see animation?