Dejan, 
The tf tree maintains state about the tree including sorted lists.  If "old" data comes in it is discarded.  Thus if your bag is longer in time than the tf cache it will throw out data which is older than the cache time from the most recent timestamped message received.  In general, time going backwards doesn't have a defined behavior.  

Tully

On Sun, May 2, 2010 at 9:48 AM, Dejan Pangercic <dejan.pangercic@gmail.com> wrote:
Hi there,

I worked through the following tutorial today:
http://www.ros.org/wiki/image_geometry/Tutorials/ProjectTfFrameToImage
and wanted to loopplay provided bag file using following command:
"while true; do rosbag play plug_on_base.bag --clock; sleep 0.1;
rostopic pub /reset_time std_msgs/Empty -1; done"
Loopplay and time-reset works but it seems that it hangs the TF tree,
i.e. from the first repetition on it never goes pass the following
line of code in the tutorial:
"tf_listener_.waitForTransform(cam_model_.tfFrame(), frame_id,
                                     acquisition_time, timeout);"

Anyone seeing something obvious?

cheers, D.
On Thu, Apr 29, 2010 at 1:53 AM, Dan Lazewatsky
<lazewatskyd@cse.wustl.edu> wrote:
> https://code.ros.org/discuss/ros-users/browse_frm/thread/1103/4095
>
> On 4/28/10 6:52 PM, Stuart Glaser wrote:
>
> while [ 1 ]; do rosbag play X.bag; sleep 1; done
>
> Not particularly satisfying, but it's what I use.
>
> -Stu
>
> On Wed, Apr 28, 2010 at 4:43 PM, Adam Leeper <aleeper@stanford.edu> wrote:
>
>
> Hi all-
> Is there a way to get rosbag to play a bag file on loop? It would be handy
> when testing things to be able to run my collected data continuously.
> Thanks!
> --Adam
>
> Adam Leeper
> Stanford University
> aleeper@stanford.edu
> 719.358.3804
>
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--
MSc. Dejan Pangercic
PhD Student/Researcher
Computer Science IX
Technische Universität München
Telephone: +49 (89) 289-17780
E-Mail: dejan.pangercic@in.tum.de
WWW: http://ias.cs.tum.edu/people/pangercic
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--
Tully Foote
Systems Engineer
Willow Garage, Inc.
tfoote@willowgarage.com
(650) 475-2827