[ros-users] Issues with rviz

[Jan Elseberg]

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> for more information on useful tf debugging
>>> strategies.
>>>
>>> Hope this helps,
>>>
>>> Eitan
>>>
>>>       
>>>> On May 20, 2010 3:38 AM, "Jan Elseberg" <j.elseberg at jacobs-university.de
>>>> <mailto:j.elseberg at 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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