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What is tf_static?

asked 2016-05-28 09:11:35 -0600

Bert gravatar image

updated 2016-05-28 13:30:02 -0600


I am currently writing my masters thesis. I used a lot of different algorithms like Hector mapping, Gmapping and AMCL. I am trying to explain those by using the RQT-graphs. In each of those graphs I see the tf_static topic. What is function of this? image description


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answered 2016-05-28 15:47:16 -0600

kmhallen gravatar image

Transforms on the /tf_static topic are assumed to never change and be valid for all timestamps.

Because tf uses tf2 under the hood, tf::TransformListener will subscribe to both the /tf and /tf_static topics automatically.

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In my launch file I use:

<!-- tf transform -->
  <node pkg="tf" type="static_transform_publisher" name="map_nav_broadcaster" args="-0.45 0 0 3.1765 0 3.1415 /base_link /laser 100"/>

Has this anything to do with /tf_static or is it just the /map_nav_broadcaster node?

Bert gravatar image Bert  ( 2016-05-30 03:14:46 -0600 )edit

No. The map_nav_broadcaster node is only publishing /tf. The only node subscribing to /tf_static is slam_gmapping.

The slam_gmapping node is listening for transforms on both the /tf and /tf_static topics.

kmhallen gravatar image kmhallen  ( 2016-05-30 12:25:16 -0600 )edit

Is there an easy way to prevent tf::TransformListeer from subscribing to the /tf_static topic? (only for the sake of clarity of the rqt_graph...)

dmeltz gravatar image dmeltz  ( 2016-06-29 00:47:40 -0600 )edit

it is possible to remap in launcher /tf_static to /tf. But I don't know if it is good idea:

<remap from="tf_static" to="tf" />

Przemek Dyszczyk gravatar image Przemek Dyszczyk  ( 2019-01-24 13:45:52 -0600 )edit

In Melodic rqt_graph has an option to group the two tf topics into a single group for visualization:

kmhallen gravatar image kmhallen  ( 2019-01-24 18:17:12 -0600 )edit

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Asked: 2016-05-28 09:11:35 -0600

Seen: 10,221 times

Last updated: May 28 '16