[ros-users] topic vs tf

[Stefan Kohlbrecher]

Hi,

if you for example just want to monitor the estimated position of an
autonomous robot, using tf can mean significant overhead. Tf can
easily consume bandwidth in the order of hundreds of kb/s, which can
choke up connections in constrained scenarios (like RoboCup, where you
have thousands of people/hundreds of teams/1-2 dozen leagues competing
for Wi-Fi). An optional lower update rate tf topic for displaying the
robot model in rviz for example would make sense for such situations.

regards,
Stefan

2011/12/9 Thibault Kruse <kruset at in.tum.de>:
> Hi,
>
> I am keen on reading an answer to this answers.ros.org question:
> http://answers.ros.org/question/2803/when-should-i-send-geometric-information-over-a
> "When should I send geometric information over a topic as opposed to TF?"
>
> I would think that TF is the best place to publish frames, meaning
> coordinate
> systems to be used as a point of reference for other geometric data.
>
> So this would be ideal for robot joints/links, sensor coordinate systems,
> and perceived joints/links of other agents (humans or robots).
>
> If possible, all those should rather be published in TF rather than anything
> else, I would believe.
>
> However I do not yet understand whether there is a downside to using TF, or
> some kind of degradation when plenty of frames are being published.
>
> The only thing I can think of is that rosbag and rxbag cannot treat
> individual
> transforms, they can only record / replay the whole tf tree.
>
> Also I guess that data with a lot of noise is not suitable as a reference
> frame
> for anything, so there is no point in publishing that in TF.
>
> Other thoughts?
>
> cheers,
>  Thibault
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