Contact Restitution with PhysX in IsaacGym

I try to change the contact restitution between one object and the ground plane.

I set restitution = 1.0 for both object and plane. I find that the simulation is still inelastic.

I am wondering what is the mechanism behind the contact?


same question here…

Hi there,

here is a step by step setup for testing the restitution:

  • in an empty stage add a Plane, two Cubes (Create->Mesh->Plane/Cube) and a Physics Material (Create->Physics->Rigid Body Material)
  • select the Plane and the two Cubes and add Physics->Colliders and for the two Cubes add [Physics->Rigid Body]
  • for the PhysicsMaterial set the Restitution value to 1.0, and the Restitution Combine Mode to average or max
  • apply the PhysicsMaterial to the second Cube physics material (in the Materials on selected models TAB)

Here is an example screenshot with the second cube’s elastic collision:


Hi, I use python to load the object from urdf file to IsaacGym.
Is it possible to modify the urdf file or the python script to achieve this elastic behavior?

My bad, I overlooked that the question is for Isaac Gym. I will forward this to the Isaac Gym team.

Hi, is there any feedback from IsaacGym team?

Hi @HarryYang, @zhuceyonghu123,

I’ll try to repro your case and take a look into the issue.


Are there any news regarding this matter?


I guess changing the restitution coefficient before creating the actor might solve it

I think I also observed weird restitution settings behavior, are you using gpu or cpu physX?

The underlying cause of this problem was tracked down and is fixed in the most recent release of Isaac Sim - 2022.2.1.