Errors in 3D Map

[Alberto]

Hello!

I'm trying to set up RTAB-Map (Kinect + Laser + Odometry) for doing Navigation with the Turtlebot robot, and everything seems to work OK except for an issue when creating the 3D Map. The issue is that it adds some wrong depth images, like if it is linking them with wrong odometry data. Here you can see an image of the error:



This issue seems to happen more often if I move the turtlebot robot at higher speeds, or when I do turns. You can see here in the 2D Map how it should be, without the displaced walls:



I've already checked the robot configurations (odometry, laser, kinect...) and everything seems to be working OK. As for the rtabmap_ros configuration, I'm using the following launch file:



I would appreciate any kind of help with the issue.

Thanks!

[matlabbe]

Is the 2d grid map created from rtabmap? If so, it may be a problem on visualization side. What is the fixed frame set in Global Options of RVIZ? It should be /map so that clouds are correctly aligned to map.

cheers

[Alberto]

Hi again!

Thanks for the quick answer. Yes, both pics are taken from RViz launched with the demo_turtlebot_rviz.launch file from rtabmap_ros package. In the second one I've just unchecked the Rtabmap cloud and Costmaps displays, but both are from the same mapping session. So, if I'm not wrong, the 2D map is created by RTAB and is remapped from the /grid_map to the /map topic in the launch file I've shown. Regarding the 2nd question, yes, the Fixed Frame in RViz is /map. Isn't there any issue that can cause the 3D Map to show displaced walls and objects, despite the 2D Map is OK?

[matlabbe]

If the 2D map is ok, it could be the transform between robot base frame and camera frame that is wrong. If you moved the camera on turtlebot, make sure you updated the corresponding TF. Otherwise, can you share a sample database?

cheers,
Mathieu

[Alberto]

Hello!

I've just checked the transform between the base and camera frames, and it's correct. I'll share with you a copy of the database. I've tried to upload it directly to the forum, but it's too large, so I've uploaded it to a hosting page. You can download it here: https://ufile.io/gn64q

Again, thanks for the great support.

[matlabbe]

Hi,

There is a synchronization problem (camera and scan don't match):


Camera  and scan seem to match only when the robot is not moving (where synchronization timing is not important). What is the frame rate of the topics?

$ rostopic hz /kobuki/laser/scan
$ rostopic hz /camera/rgb/image_raw
$ rostopic hz /camera/depth/image_raw
$ rostopic hz /camera/rgb/camera_info

cheers,
Mathieu

[Alberto]

Hi Mathieu,

This makes a lot of sense. I was suspecting of something like this, but just couldn't figure out what exactly was happening. The rates are:

/kobuki/laser/scan: 22Hz
/camera/rgb/image_raw: 20Hz
/camera/depth/image_raw: 20Hz
/camera/rgb/camera_info: 8Hz

[matlabbe]

The camera info rate should be as fast as the other camera topics. Verify the configuration of the node publishing it.