Jan, <div>Are you running rviz on a seperate machine? If so make sure that the clocks are synced using ntp or similar between the multiple machines. </div><div><br></div><div>To see the tf tree that rviz is using try running "view_frames --node=rviz_******" where ******* is the UUID of the anonymous rviz process which you can get from rosnode list. </div>
<div><br></div><div>Tully<br><br><div class="gmail_quote">On Thu, May 20, 2010 at 9:19 AM, Jan Elseberg <span dir="ltr"><<a href="mailto:j.elseberg@jacobs-university.de">j.elseberg@jacobs-university.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Wim,<br>
<br>
the timestamps of the laser scans are concurrent to the ones I'm getting<br>
with "rostopic echo /tf".<br>
I was under the impression that tf would give me an error of some kind<br>
in this scenario ?<br>
Also, if the issue lies with my tf-tree, shouldn't there be similar<br>
problems in my node<br>
that transforms the laser scans into the /map frame using the<br>
tf::TransformListener ?<br>
<br>
Regards,<br>
<font color="#888888"><br>
Jan<br>
</font><div><div></div><div class="h5"><br>
<br>
<br>
Wim Meeussen wrote:<br>
> Jan,<br>
><br>
> Your tf tree looks fine, but it is possible that the timestamps of<br>
> your laser scans are wrong. Your tf buffer keeps a 10-seconds window<br>
> of transformations. When the timestamp of your laser scan does not fit<br>
> in that 10 seconds window, tf won't be able to transform it. From the<br>
> data you sent, it looks like your tf buffer is nicely synchronized<br>
> with the current time in your system, so I would suspect that your<br>
> laser scans have timestamps that are either more than 10 seconds in<br>
> the past, or some number of seconds in the future.<br>
><br>
> You can check the timestamp of your laser scans using "rostopic echo<br>
> laser_scan/header/stamp".<br>
><br>
> Wim<br>
><br>
><br>
><br>
><br>
>> I've attached the results of view_frames. I have also tried the other stuff<br>
>> on the troubleshooting guide. Transformations between the laser frame and<br>
>> every other frame work fine. Across the longest tf-chain (/front_laser to<br>
>> /map) the average delay is approx 25ms and the maximal delay is approx.<br>
>> 55ms. From this it appears to me that the tf-tree is correctly set up, but<br>
>> maybe there is something else I can check?<br>
>><br>
>> Regards,<br>
>><br>
>> Jan Elseberg<br>
>> Eitan Marder-Eppstein wrote:<br>
>><br>
>>> Jan,<br>
>>><br>
>>> It sounds like something may be wrong with your transform tree. Can you<br>
>>> try running "rosrun tf view_frames"? This will generate a PDF of the current<br>
>>> transform tree structure. You may also want to check the troubleshooting<br>
>>> link on the sidebar of this page: <a href="http://www" target="_blank">http://www</a> .<a href="http://ros.org/wiki/tf" target="_blank">ros.org/wiki/tf</a><br>
>>> <<a href="http://ros.org/wiki/tf" target="_blank">http://ros.org/wiki/tf</a>> for more information on useful tf debugging<br>
>>> strategies.<br>
>>><br>
>>> Hope this helps,<br>
>>><br>
>>> Eitan<br>
>>><br>
>>><br>
>>>> On May 20, 2010 3:38 AM, "Jan Elseberg" <<a href="mailto:j.elseberg@jacobs-university.de">j.elseberg@jacobs-university.de</a><br>
>>>> <mailto:<a href="mailto:j.elseberg@jacobs-university.de">j.elseberg@jacobs-university.de</a>>> wrote:<br>
>>>><br>
>>>> Hi everyone,<br>
>>>><br>
>>>> I am trying to get our robot to work with the navigation stack of ros.<br>
>>>> I've been following the tutorial on<br>
>>>> <a href="http://www.ros.org/wiki/navigation/Tutorials/RobotSetup" target="_blank">http://www.ros.org/wiki/navigation/Tutorials/RobotSetup</a> . After setting<br>
>>>> up the robot with a tf-tree and sensor nodes , I have noticed a problem<br>
>>>> with rviz. I am unable to display the laserscan messages in any frame<br>
>>>> other than the laser coordinate system itself, i.e., whenever I select a<br>
>>>> <Fixed_Frame> other than /front_laser the status of the laser scan<br>
>>>> display shows the error:<br>
>>>><br>
>>>> "Unknown reason for transform failure".<br>
>>>><br>
>>>> Also, this warning appears in the bash:<br>
>>>><br>
>>>> [WARN] 1274341043.701801000: MessageFilter [target=/base_link ]: Dropped<br>
>>>> 99.03% of messages so far. Please turn the [ros.rviz.message_notifier]<br>
>>>> rosconsole logger to DEBUG for more information.<br>
>>>><br>
>>>> Doing so gives me these repeating debug messages:<br>
>>>><br>
>>>> MessageFilter [target=/base_link ]: Added message in frame /front_laser<br>
>>>> at time 1274341252.994, count now 10<br>
>>>> MessageFilter [target=/base_link ]: Removed oldest message because<br>
>>>> buffer is full, count now 10 (frame_id=/front_laser,<br>
>>>> stamp=1274341252.813649).<br>
>>>><br>
>>>> This suggests a problem with the tf-tree to me. However, when using the<br>
>>>> "transformPoint(...)" function of tf::TransformListener in my own nodes<br>
>>>> to transform the laser scan into the global frame everything works as<br>
>>>> intended with no errors/warnings.<br>
>>>><br>
>>>> Does someone have an idea what I am doing wrong?<br>
>>>><br>
>>>> Thank you for any help!<br>
>>>><br>
>>>><br>
>>>> Jan Elseberg<br>
>>>><br>
>>>> _______________________________________________<br>
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>>>><br>
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>><br>
>><br>
>><br>
><br>
><br>
><br>
><br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Tully Foote<br>Systems Engineer<br>Willow Garage, Inc.<br><a href="mailto:tfoote@willowgarage.com">tfoote@willowgarage.com</a><br>(650) 475-2827<br>
</div>