Pointcloud configuration options (intensity, noise, pointcloud structure) for Isaac Sim and ROS Interface

Omniverse Isaac Sim
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1

Hello there,

I am planning to create an environment to virtually validate perception algorithms for a mobile robot using camera and lidar.
Some of the lidar perception algorithms my team developed make use of specific features like intensity values of the points as well as the structure of the point cloud in the ROS messages (row-by-row structure like in the ROS messages obtained by Ouster rotating lidars) and the fact that a point cloud has a fixed number of points (even when the laser was not reflected back, the point gets set to 0,0,0 in the message).

According to my colleague who is working with the synthetic data I created using Isaac Sim, the point clouds obtained from the real sensor and Isaac Sim differ in the way that:

  1. There are no intensity values present for the points
  2. The point cloud in the ROS pointcloud2 message is structured column-wise instead of row-wise
  3. The pointcloud size differes (it contains only points that were reflected)

As a fourth point, real point clouds contain a certain amount of noise, which the Sim clouds have not.

My question is:
Are there ways to modify the lidars or the nodes in the action graphs in the way to get point clouds that match the “real” data with respect to the mentioned four points?

Any tips or guidance is very appreciated!

Best regards
Kevin

3

I can only speak to the rtx lidar.

You can keep the points that are not hits if you set the keepOnlyPositiveDistance parameter on the ComputeRTXLidarPointCloud node. That will keep the point count the same each frame.

Intensity should be coming out of that node as well, but I am not sure it is fed into ros for any of our examples.

@Hammad_M may know better, but I think the coloumn/row wise order is fixed in our patch release out soon.

5

Thank you for providing such a good simulation for the robot. I aslo need intensity information from the point cloud to ros. I know that the action graph like “Isaac Compute RTX Lidar Point Cloud Node” can output intensity information. But the problem is “ROS2 RTX Lidar Helper” or “ROS2 Publish Point Cloud” no intensity information in the field.
I’m looking forward to getting a solution. Thanks.