Scripted Trajectories / Moving Objects

Hello all,

I’d like to have some moving objects in a scene to evaluate the robots reaction to them. Therefore it would be great to have a way of scripting a trajectory, ideally combined with a animated person. The animated part shouldn’t be a problem with the help of Omniverse, the Reallusion character samples look very promising. The problem is, that when i create a collider for them, it is created in the characters T-Pose and not moving with him. The moving collider is needed for the LiDAR-Scanner.

Is there a way to get a matching collider in Isaac Sim or something else which is comparable to the scripted trajectories for actors in Gazebo? (Gazebo : Tutorial : Make an animated model (actor)) That would be great!

Thanks for your help!

Can you tell us which version of Isaac Sim/SkelJoint extension/Xform constraint extension you’re using? @XuNie and @jiayuan can advise the right combo. Thanks.

Hi and thanks for your reply.

I’m using Isaac Sim version 2021.1.1, regarding the extensions I’m not quite sure.
In Isaac Sim there are no extensions available under the “Animation” category, in Create 2021.3.6 the SkelJoint extension v102.2.1 is available. Please find Screenshots from both programs below.

Additionally I noticed that i can’t view the skeleton in Isaac Sim. When i activate the visualization under “show by type” I’m only getting two warning messages:

2021-11-09 11:46:48 [Warning] [omni.client.plugin] Main: usd_plugin: Unhandled ProcessPropertyChange callback for cachePath </World/Worker/ManRoot/Worker/Worker/Animation> in UsdSkelImagingSkelAdapter.

2021-11-09 11:46:48 [Warning] [omni.usd] Warning: in ProcessPropertyChange at line 519 of /buildAgent/work/ca6c508eae419cf8/USD/pxr/usdImaging/usdSkelImaging/skeletonAdapter.cpp -- Unhandled ProcessPropertyChange callback for cachePath </World/Worker/ManRoot/Worker/Worker/Animation> in UsdSkelImagingSkelAdapter.

Kind regards,

Hi Chr1s,

Do you still have this issue with Isaac Sim 2021.2.0?


Hi Liila,

thanks for coming back to this issue.

With the latest update i can now visualize the skeleton.

However my initial request remains unsolved. As you can see in the screenshot, the collider for the Worker is still in its static T-pose.
I would really appreciate it to have a moving collider for the worker and also - like mentioned in the first post - to have a way to script trajectories.

Thanks a lot for your efforts!


apparently, this is not currently possible… :(

hi @ltorabi any news on this?

Hi @eliabntt94, moving objects functionality will be available in our upcoming Isaac Sim release in December.

Hi, great to hear that. Will it work also for lidar sensing? Maybe you should also double check [BUG] Bounding boxes 3d are not updated for animated meshes this. I just discovered this problem.

Hi @rthaker. I was experimentic with LiDAR and had many issues with dynamic objects.

Perhaps the new version is aimed at solving those but I was wondering if any solution would be portable at the previous versions of the code.

Currently, both objects animated with timeframes keys and with mesh point cashes are not hit by lidar even though collider is generated correctly for the latter.

Hi @eliabntt94 , are you still seeing these issues on the latest Isaac Sim 2022.2.0 release?

I’ll check it out probably in January. I need to adapt the pipeline to the new api probably and we’re busy writing the paper.😊

I checked briefly and they seem still there. However, I noticed you introduced an RTX LiDAR, which might be helpful. I’ll sync back in Jan.

Hi @rthaker. Sorry for being so late answering this.


  • dynamic meshes I still get the error that physix currently does not support time sampled points meshes and therefor do not work with normal lidar, nor collisions.
  • “flying” objects gets now detected by lidar (normal) if animated through a curve editor
  • RTX lidar I’m currently testing. I had some issues but will sort them out. (example is running so I guess it’s something I’m doing wrong)

Also, I got UsdToMdl: Reached invalid assignment for parameter 'opacity_constant'. Tried to assign a 'int'(USD) to a 'float'(MDL). loading an old USD scene. It should be straightforward to solve this on your side.

yes, currently you can only detect the people with RTX-lidar, there is no colliders for them

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