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rviz not able to visualize laser scan

asked 2015-11-27 14:42:53 -0500

rb gravatar image

updated 2015-11-27 14:44:18 -0500

I'm having trouble with RVIZ being unable to show laser scan point data. I'm not sure if this is an RVIZ problem, a problem in my RVIZ config, or a problem with my setup in general (ie: i'm doing something bad with coordinate frames or something along those lines).

Background: I am new to using tf frames within ROS. I decided to learn how to use tf and frame headers to properly tag all my sensor data so I can use provided packages (like for example hector_mapping). I'm going to try and give background to how I arrived at where I am now in case the context helps because I'm really not sure what I did to break it.

Here's how I used to be able to see my laser scan data (it is from a little neato lidar):

  1. open rviz
  2. add LaserScan
  3. Set topic to neato_scan topic

Next I created a node which transforms my neato_laser frame to base_link, and then configured hector_mapping and launched it. It worked well and I was able to visualize both the map and laser scan data after configuring rivz.

At some point (the problem is I'm not sure exactly what changes I made to trigger, if any) RVIZ stopped showing laser scan data.

Here is what I know:

  • Hector_mapping is still able to see and transform the laser_scan data correctly. The map generates fine and the robot is able to localize from the laser data + map. To me this indicates the coordinate frame transforms are infact setup correctly.
  • I am able to verify there is scan data being generated by doing rostopic echo /neato_scan
  • In RVIZ, no matter what I try, I can't get it to visualize the laser scan data.

I've tried with the full config that allowed me to see the map + laser scan data before, and I've also tried reverting to setting all frames (fixed frame, target frame, etc) to neato_laser and only adding the LaserScan to the visualization.

Present Situation:

  • LaserScan shows status "OK" and under topic it shows xxx messages received which counts up correctly.
  • Occasionally a single point will show up for a split second, usually at the origin. If i place a large decay time, it will show several points, mostly at the origin, and some at impossible locations (for example in mid air directly above the origin)
  • There is no evidence of any errors. All of RVIZ status fields show OK with green check mark.

ITs quite likely I'll need to provide more info/do some debugging to trace this problem but I'm not sure how to proceed. Any help in how to sort this out is much appreciated.

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answered 2015-11-29 14:16:56 -0500

rb gravatar image

so I went ahead and restarted the computer for the first time in a couple weeks and the problem resolved itself.

Not only is the point cloud being rendered correctly now, but also things that were missing before that I didn't notice (such as labels on tf transforms) have popped up as well.

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What? You didn't change anything within those weeks?

zkytony gravatar image zkytony  ( 2016-09-01 19:07:45 -0500 )edit

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Asked: 2015-11-27 14:42:53 -0500

Seen: 2,699 times

Last updated: Nov 29 '15