Collision filter

tareq.khouja · September 8, 2022, 5:29pm

Hello all,
is it possible in IsaacSim to group prims in collision groups so that collision would be disabled for every prim that is in the same group. this is for example possible in Isaac Gym.
ex: the following objects do overlap on some areas, but do to the collision group tjey don’t collide with each other but still can collide other objects, like robots…

rgasoto · September 22, 2022, 6:52pm

Hello! Yes it is possible to create collision groups and filter between them.
Here’s how: Rigid-Body Simulation — Omniverse Create documentation

tareq.khouja · December 14, 2022, 3:04pm

is there way to assign those filter groups throw python code? the only way described in the documentation is throw the GUI which I do not use.

gstate · December 25, 2022, 5:34am

Hi @tareq.khouja,

If you’re using the gym cloner, you can use the filter_collisions API documented here:
https://docs.omniverse.nvidia.com/py/isaacsim/source/extensions/omni.isaac.cloner/docs/index.html#omni.isaac.cloner.cloner.Cloner.filter_collisions

This is the default behavior in the OmniIsaacGymEnvs examples when cloning environments:

github.com

NVIDIA-Omniverse/OmniIsaacGymEnvs/blob/main/omniisaacgymenvs/tasks/base/rl_task.py#L131


      
              super().set_up_scene(scene)
          
          
    collision_filter_global_paths = list()
              if self._sim_config.task_config["sim"].get("add_ground_plane", True):
                  self._ground_plane_path = "/World/defaultGroundPlane"
                  collision_filter_global_paths.append(self._ground_plane_path)
                  scene.add_default_ground_plane(prim_path=self._ground_plane_path)
              prim_paths = self._cloner.generate_paths("/World/envs/env", self._num_envs)
              self._env_pos = self._cloner.clone(source_prim_path="/World/envs/env_0", prim_paths=prim_paths, replicate_physics=replicate_physics)
              self._env_pos = torch.tensor(np.array(self._env_pos), device=self._device, dtype=torch.float)
              self._cloner.filter_collisions(
                  self._env._world.get_physics_context().prim_path, "/World/collisions", prim_paths, collision_filter_global_paths)
              self.set_initial_camera_params(camera_position=[10, 10, 3], camera_target=[0, 0, 0])
              if self._sim_config.task_config["sim"].get("add_distant_light", True):
                  create_distant_light()
          
          
def set_initial_camera_params(self, camera_position=[10, 10, 3], camera_target=[0, 0, 0]):
              if self._env._render:
                  viewport_api_2 = get_viewport_from_window_name("Viewport")
                  viewport_api_2.set_active_camera("/OmniverseKit_Persp")
                  camera_state = ViewportCameraState("/OmniverseKit_Persp", viewport_api_2)

This is all implemented using USD python APIs on top of the USD Physics Schema. If you’d like to do something similar yourself without using the cloner APIs, I’d recommend reviewing the code in the cloner that applies the collision filtering. If you navigate to the Isaac Sim Package Path you can find the code the cloner filtering API uses for this in exts/omni.isaac.cloner/omni/isaac/cloner/cloner.py

Take care,
-Gav