Re: [ros-users] Issues with rviz

>     Wim,

>     the timestamps of the laser scans are concurrent to the ones I'm
>     getting
>     with "rostopic echo /tf".
>     I was under the impression that tf would give me an error of some kind
>     in this scenario ?
>     Also, if the issue lies with my tf-tree, shouldn't there be similar
>     problems in my node
>     that transforms the laser scans into the /map frame using the
>     tf::TransformListener ?

>     Regards,

>     Jan

>     Wim Meeussen wrote:
>     > Jan,
>     >
>     > Your tf tree looks fine, but it is possible that the timestamps of
>     > your laser scans are wrong. Your tf buffer keeps a 10-seconds window
>     > of transformations. When the timestamp of your laser scan does
>     not fit
>     > in that 10 seconds window, tf won't be able to transform it.
>     From the
>     > data you sent, it looks like your tf buffer is nicely synchronized
>     > with the current time in your system, so I would suspect that your
>     > laser scans have timestamps that are either more than 10 seconds in
>     > the past, or some number of seconds in the future.

>     >
>     > You can check the timestamp of your laser scans using "rostopic echo
>     > laser_scan/header/stamp".

>     >
>     > Wim

>     >

>     >

>     >

>     >
>     >> I've attached the results of view_frames. I have also tried the
>     other stuff
>     >> on the troubleshooting guide. Transformations between the laser
>     frame and
>     >> every other frame work fine. Across the longest tf-chain
>     (/front_laser to
>     >> /map) the average delay is approx 25ms and the maximal delay is
>     approx.
>     >> 55ms. From this it appears to me that the tf-tree is correctly
>     set up, but
>     >> maybe there is something else I can check?

>     >>
>     >> Regards,

>     >>
>     >> Jan Elseberg
>     >> Eitan Marder-Eppstein wrote:

>     >>
>     >>> Jan,

>     >>>
>     >>> It sounds like something may be wrong with your transform
>     tree. Can you
>     >>> try running "rosrun tf view_frames"? This will generate a PDF
>     of the current
>     >>> transform tree structure. You may also want to check the
>     troubleshooting
>     >>> link on the sidebar of this page: http://www .ros.org/wiki/tf
>     <http://ros.org/wiki/tf>
>     >>> <http://ros.org/wiki/tf> for more information on useful tf
>     debugging
>     >>> strategies.

>     >>>
>     >>> Hope this helps,

>     >>>
>     >>> Eitan

>     >>>

>     >>>
>     >>>> On May 20, 2010 3:38 AM, "Jan Elseberg"
>     <j.elseberg@jacobs-university.de
>     <mailto:j.elseberg@jacobs-university.de>
>     >>>> <mailto:j.elseberg@jacobs-university.de
>     <mailto:j.elseberg@jacobs-university.de>>> wrote:

>     >>>>
>     >>>> Hi everyone,

>     >>>>
>     >>>> I am trying to get our robot to work with the navigation
>     stack of ros.
>     >>>> I've been following the tutorial on
>     >>>> http://www.ros.org/wiki/navigation/Tutorials/RobotSetup .
>     After setting
>     >>>> up the robot with a tf-tree and sensor nodes , I have noticed
>     a problem
>     >>>> with rviz. I am unable to display the laserscan messages in
>     any frame
>     >>>> other than the laser coordinate system itself, i.e., whenever
>     I select a
>     >>>> <Fixed_Frame> other than /front_laser the status of the laser
>     scan
>     >>>> display shows the error:

>     >>>>
>     >>>> "Unknown reason for transform failure".

>     >>>>
>     >>>> Also, this warning appears in the bash:

>     >>>>
>     >>>> [WARN] 1274341043.701801000: MessageFilter [target=/base_link
>     ]: Dropped
>     >>>> 99.03% of messages so far. Please turn the
>     [ros.rviz.message_notifier]
>     >>>> rosconsole logger to DEBUG for more information.

>     >>>>
>     >>>> Doing so gives me these repeating debug messages:

>     >>>>
>     >>>> MessageFilter [target=/base_link ]: Added message in frame
>     /front_laser
>     >>>> at time 1274341252.994, count now 10
>     >>>> MessageFilter [target=/base_link ]: Removed oldest message
>     because
>     >>>> buffer is full, count now 10 (frame_id=/front_laser,
>     >>>> stamp=1274341252.813649).

>     >>>>
>     >>>> This suggests a problem with the tf-tree to me. However, when
>     using the
>     >>>> "transformPoint(...)" function of tf::TransformListener in my
>     own nodes
>     >>>> to transform the laser scan into the global frame everything
>     works as
>     >>>> intended with no errors/warnings.

>     >>>>
>     >>>> Does someone have an idea what I am doing wrong?

>     >>>>
>     >>>> Thank you for any help!

>     >>>>

>     >>>>
>     >>>> Jan Elseberg

>     >>>>
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>     >>>>
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>     >>

>     >>

>     >

>     >

>     >

>     >

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