Concerns regarding physics simulation features in Isaac and Omni Gym

With integration into Omniverse, I assume that the PhysX/Flex backend options will be replaced/unified with PhysX 5. I wonder if any current features/capabilities will be lost in this transition, or, conversely, if any new features will be gained.

Points of confusion:

Specific interest:

  • Although the above examples refer to soft bodies, I am more interested in particle simulation. Interactions with larger granular material could do for a start, eventually moving towards smaller, sand-like particles, subject to available memory and computational resources.


  • Once integrated into Omniverse, is there anything preventing particle simulation in Omni Gym?
  • If so, would you recommend to continue with Isaac Gym Preview 3 and its Flex backend, or do the same or similar limitations apply?
  • Generally, how would one (best) approach simulating interactions with granular material in current and near releases of Isaac/Omni Gym? I.e., if otherwise infeasible, could one approximate it with many small (yet sufficiently large and few) objects and either backend, like an extrapolation of the balls of solitude example, or is this approach too problematic?

Thank you for taking the time, your recent GTC presentation and answers, and your ongoing impressive work.

Hi @marledu,

The various soft body features are available now in the current Omniverse Create, and will be exposed in the upcoming Isaac Sim GA release. You can review the details here: Physics Core — Omniverse Extensions documentation

The particle features you are specifically interested in are available through the omni.physx.preview extension, which you need to enable via the Extensions window. Once enabled, the PBD Particle samples are available from Window->Physics->Demo Scenes under the Preview Samples area.

Once we have Gym tensor API features available in Omniverse, all of the new PhysX features will interact properly with RL environments, though we may not necessarily have tensor APIs to read or modify physics state on all of the new features immediately. For example, you may be able to get aggregates of contact forces between rigid bodies and a particle / fluid simulation, but not necessarily the details of each and every particle collision.

I’m not sure that I would recommend using a large number of individual rigid body spheres in the current Isaac Gym to simulate granular material. It’s possible that it would work, but it’s definitely not something that we’ve tried internally, and is likely to have scalability issues.

I’d definitely recommend starting with the PhysX preview capabilities available now in Create, and see whether you can get the granular interactions you’re looking for with the PBD particle systems. If so, you’ll definitely be in good shape once we have the Gym features available in Omniverse.

You can certainly try exploring some of the particle simulation features in the Flex backend of Isaac Gym Preview 3, but note that it’s not really something that we can support well, and we don’t have any examples to help you out.

Take care,

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Thank you for the insightful clarification and recommendations. I am now eager to experiment with PBD in Create, while I continue to iterate on related and other parts of my project in Isaac Gym.

I look forward to seeing it all come together when the time comes and hope to share some useful feedback and examples along the way.

Sorry, did you meant these features will be in the Isaac Sim GA release, or the current Omniverse Create releases? It would be soooo cool if they were available in the Isaac Sim GA release.

Hi @utku_oguzman,

Yes - the omni.physx.preview features are available now in the current release of Create, and they are coming to the new release of Isaac Sim in the next release.

Take care,