How to publish TF for slam_gmapping

Question

Hi,

I completed the tutorial on [slam_gmapping using Logged data]. When I play the basic_localisation_stage.bag and run "rostopic echo tf", I realised that there are 3 messages published every 100ms:

1. odom-->base_footprint
2. base_footprint-->base_link
3. base_link-->base_laser

So, if i want to run gmapping with TF, do I need to publish all those three types messages in every cycle? (2) and (3) have fixed values, and may be unneccessarily to be published again. So, they can be published only at the beginning of the process.

I am not sure how the slam_gmapping works with the TF, as in does it subscribe all the three messages in every cycle? I need to minimise data transfer since I am using Labview to transfer the odometry data to ROS.

Any help would be much appreciated. Thanks

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Originally posted by clonzz on ROS Answers with karma: 60 on 2013-09-01

Post score: 0

Answer 1

You only need to provide some transformation chain from /odom to the laser frame. It doesn't matter what that is and how it is constructed. Usually it depends on the robot setup.

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Originally posted by dornhege with karma: 31395 on 2013-09-02

This answer was ACCEPTED on the original site

Post score: 0

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Original comments

Comment by Ben_S on 2013-09-02:
Its also important, that there is some kind of base_link. Currently released gmapping uses odom -> base_link tf for motion estimation. Newest version from git uses odom -> laser frame for motion, but needs base_link -> laser to find out about the orientation of the laser.