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Where can I get TransformStamped values?

asked 2018-10-24 04:24:58 -0600

stevemartin gravatar image

I am quite new to ROS and I am creating a new frame "map" as I am using map_server to publish map and also creating a tf2 from map to odom, which is required for the localization. So the first step, is to create a TransformStamped object with details filled in. The header.frame_id and header.child_id is obivious, map and odom, but where can I obtain the transform values? When I have included amcl package and run rosrun tf tf_echo map odom I got these results and I wonder where can I get them?:

 At time 13.558
- Translation: [0.013, -0.002, 0.000]
- Rotation: in Quaternion [-0.000, 0.000, 0.000, 1.000]
            in RPY (radian) [-0.000, 0.000, 0.000]
            in RPY (degree) [-0.000, 0.001, 0.010]
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see related: #q306575

mgruhler gravatar image mgruhler  ( 2018-10-25 01:46:48 -0600 )edit

@stevemartin: you may want to review REP-105. That should make the relationship between all these frames a little clearer.

@mgruhler is correct: those values are not "special", they are the result of localisation of your robot in the map frame.

gvdhoorn gravatar image gvdhoorn  ( 2018-10-25 02:44:51 -0600 )edit

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answered 2018-10-25 01:42:26 -0600

mgruhler gravatar image

Well, actually it is the localization node (i.e. amcl, for example) which produces the transfrom from map to odom. So this is where those values come from.

If you want to do localization yourself, your code needs to produce those values...

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Asked: 2018-10-24 04:24:58 -0600

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Last updated: Oct 25 '18