RTX Lidar send returns of its own meshes

[heiscsy]

Isaac Sim Version 4.5.0
Operating System: ubuntu 22.04

Hi all,

When I add a RTX lidar (Hesai XT32) in the simulation and setup the correspondent action graph to publish it into ros2, I found a lot of point cloud will be created from its own shell (mesh). And the intensity of the return is also being distorted by the mesh.

Left side is the debugging view of the point cloud and right side is the rviz point cloud. You can see a lot of scan layers hit the body of the lidar.

And everything is fine if I deactivate the mesh of the XT32 lidar.

Is this normal? If so, how can I create a lidar transparent material to keep the appearance of the robot but be permissive of the lidar scan?

Best,
Yuhan

[zhengwang]

You probably need to change the parameter nearRangeM of your lidar to exclude its body. Please refer to these two documentations: RTX Lidar Sensor — Isaac Sim Documentation, Omniverse Lidar Extension — Isaac Sim Documentation

The default value of nearRangeM is 0.05. After setting nearRangeM to 0.2, I don’t see reflection from lidar itself:

[heiscsy]

Thanks for answering. But changing nearRangeM is just filtering out all the reflection points hit on the lidar, which means we will still lose points for detection. The laser scan still cannot penetrate the mesh

This is after change the nearRangeM to 0.2, the left over points around the lidar is not from the lidar itself but from the other part of the lidar mount.

This is deactivating the mesh after change the nearRangeM to 0.2.

You can see there are obvious missing scans before deactivating the mesh even when the cutting off distance is set to 0.2

[zhengwang]

Let me pass this to our internal team.

[zhengwang]

I am able to confirm with our engineers that this is a bug. They will work on it.
Thanks for reporting this!

[zhengwang]

Hey @heiscsy, setting the parameter “rangeOffset” to 0.2 in Hesai lidar config would remove the obstruction. Please refer to Omniverse Lidar Extension — Isaac Sim Documentation.
I also tried it and here is how it looks: