how to assemble scans from vertical planar lidar

asked 2017-08-06 03:38:14 -0500

AlexR gravatar image


I am now learning the laser_assembler package for converting laser scans into point cloud data for 3D perception. The sample bag file that is provided contains laser data with topics /tf and /tilt_scan. From what I assume is that the /tilt_scan topic comes from a tilting laser system like in the PR2 robot. My question is- Can the laser assembler be used with a fixed laser sensor which is vertically mounted with respect to the robot motion instead of regular horizontally placed sensors that are used for grid mapping.

My aim is to use two laser sensors, one horizontal for 2D ICP and grid mapping and navigation, and the other one fixed vertically at a certain height, and then assemble the scans into point cloud data for 3D mapping. If yes, how do I use the topics for say laserh(horizontal) and laserv(vertical). I can remap them to topics /scanh and /scanv. I am sure many people must have tried this system since its the most trivial arrangement that comes to mind. Can someone point me to right direction so that I can move ahead with my plan or provide git links or packages that I can use to run this.

Any help would be deeply appreciated. Thank you.

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As I see, you would need to launch two instances laser_scan_assember for each and then add the two resulting point clouds.

naveedhd gravatar image naveedhd  ( 2017-08-07 08:58:21 -0500 )edit

Hi, Thanks for the answer, can you elaborate as to how to accomplish that?

AlexR gravatar image AlexR  ( 2017-08-16 07:50:10 -0500 )edit
  1. Launch 2 instances of laser_assembler as described in 4.3 of laser_assembler wiki. (group them under namespaces to separate service names)
naveedhd gravatar image naveedhd  ( 2017-08-21 04:27:33 -0500 )edit

and 2. Write your own version of periodic_snapshotter that gets point_cloud from both and adds them.

naveedhd gravatar image naveedhd  ( 2017-08-21 04:28:17 -0500 )edit

Hi, Thanks, I will try this and report back.

AlexR gravatar image AlexR  ( 2017-08-22 21:54:23 -0500 )edit

Hi Alex! I tried with gazebo and I was able to get two pointclouds, assembled every 1 second, using the approach above. Though the orientation for vertical scan was wrong, but didn't go further.

naveedhd gravatar image naveedhd  ( 2017-08-23 02:01:59 -0500 )edit