Issac Sim soft body Simulation mesh Resolution and Young's modulus problem

I am now confused by the Simulation mesh Resolution and Young’s modulus in the SIsaac sim. In Physics, Young’s Modulus can affect the degree of the deformation. However, I found higher Simulation mesh Resolution in Isaac sim can result in larger deformation, and lower Simulation mesh Resolution results in smaller deformation. Simulation mesh Resolution is just a hyper-parameter not a physical property of an object. If I set Young’s modulus as the real one, the deformation of the soft body in the simulation is highly related to the hyper-parameter, how can I determine the Simulation mesh Resolution to make the simulation results close to the truth? In this situation, how can I guarantee the simulation result and the deformation are accurate?

here is the illustration of the simulation result comparison on different Simulation mesh Resolution but the same Young’s modulus.

Hi @shilelieming,
this is a known problem. In principle identical young’s modulus should result in equal deformation, but in practice the solution is dependent on timestep, iteration count and simulation mesh resolution. The dependence on iteration could and resolution should mainly appear if the solver doesn’t converge. Which is something we are trying to improve in general, but won’t be able to fix completely.
Your best bet is to see whether increasing iteration count and reducing time step size would help to make your results more consistent.


Thanks very much for informing me that, which is very significant for me. According to your reply, I think the deformation simulation and mechanical simulation are not accurate, compared with the traditional Finite Element Method (FEM). That is right? I hope the Mechanical simulation in Isaac gym is accurate and consistent. I have read the paper Sim-to-Real for Robotic Tactile Sensing via Physics-Based Simulation and Learned Latent Projections from NVIDIA and UW, what is mentioned in this paper is that the mechanical simulation results of the Isaac gym are consistent and accurate enough.