[Remote Mapping] RTAB-Map does not subscribe to odom topic, the laser scan does not match

[tom haverford]

Hi Mathieu,

I am trying to do remote mapping using the http://wiki.ros.org/rtabmap_ros/Tutorials/RemoteMapping. The nodelet file(rgbd_sync) runs on the odroid and I am launching the rtabmap.launch on my laptop. Mapping using the visual odometry works fine, but I want to use the rgbd topic, scan and odometry(whe
el) to get a better and accurate map.

I used the rtabmap.launch file and these are some of the parameters I set for using the scan and odom topic.

For odom topic:
<arg name="odom_frame_id"           default="odom"/>
<arg name="odom_topic"               default="/odom"/> 
<arg name="visual_odometry"          default="false"/>
<arg name="odom_sensor_sync"         default="true"/>

For  scan topic:
  <arg name="subscribe_scan"          default="true"/>
  <arg name="scan_topic"              default="/scan"/>

The odom topic is published, I verified using both rostopic hz and rostopic echo, but the rtabmap does not subscribe to the odom topic, I ran both the rostopic info /odom and also verified using the rqt_graph, but the odom topic is not subscribed by rtabmap.

Here are some of the results:





The above images are a result of rotating the robot in the same place.

I reviewed the db file and ensured the depth and color image are aligned.The 2d map shows the scan being scattered




In the remote mapping tutorial it was mentioned that the scan and odom should be passed through a relay node. Can this be the problem.

Can you suggest what may be the problem for the scan scattering and also the odom topic not subscribed by rtabmap?
 Any suggestions will be helpful.

[tom haverford]

Hey Mathieu,

I tried using the data throttled topics instead of the rgbd image, but still the rtabmap is not subscribing to the odom topic.

Also, when I launch the rtabmap node with compressed as true, it subscribes to the relay topics, but the relay image and depth topics are not published by the data throttle node. How do I publish the relay topics?

[matlabbe]

If odom_frame_id is set, rtabmap won't subscribe to odometry topic, it will use TF instead for odometry.

For the scan scattering issue, this may be fixed with recent version. Which rtabmap version do you use?

Relays are optional, you can try to make it work without relays first, then add relays on remote computer if there are more than one process using the same topic published by the remote computer.

[tom haverford]

1) Ok, I will remove the odom frame id to use the odom topic.

2) This is the rtabmap version I am using:  0.20.2

3) This is the rate of the topics on the laptop side. ( I use the laptop for mapping and visualization, the topics are being published by the odroid on the robot)





Does the rate at which the topics are being published lead to problems?


Can you suggest which is a better method?
Doing  'mapping on the odroid and visualization on the laptop' OR  'doing the mapping and
visualization both on the laptop'.

At the start of the mapping when the robot is stationery, the rgbd image is clear, the mismatch starts only when I start moving the robot.

[tom haverford]

Update:

So, I tried running the mapping on the odroid and visualizing on the laptop only using the rtabmap/mapData

On the odroid side, this is the rate at which the topics are published:




On the laptop side this is the rate of the rtabmap/mapData:




 I tried visualizing the rtabmap/mapData on the rviz (laptop side) by moving the robot with a forward motion:





I am not sure, where the error is coming from, I tried out various methods and referred to all the demo launch files, still I am not able to get a proper map. Any help would be much appreciated, I am stuck on this problem for 3 weeks now.