Hai,
The tf library is not robust to time jumping backwards. The first time you
playback it will work, but the second time time the incoming data will be
older than the tf buffer and be tossed on on reciept.
http://www.ros.org/wiki/tf/Errors%20explained#Error:_TF_OLD_DATA
Tully
On Tue, Jul 27, 2010 at 12:35 PM, Hai Nguyen <
haidai@gmail.com> wrote:
> Hi,
> Hi,
>
> I'm trying to assemble some laser scans into a point cloud using
> laser_assembler tutorial [1] but the periodic_snapshotter keeps
> reporting that it is only publishing empty messages with zero points:
> [ INFO] [1280258736.674914761, 1275001489.217034967]: Published
> Cloud with 0 points
>
> On closer investigation this seems to be caused by a TF_OLD_DATA error
> generated by scan_assembler. Is there a recent change to how the time
> mechanism works in ROS? I'm running all these nodes on the same
> computer, using --clock with "rosbag play" (on the provided bag file
> laser.bag), and tried to run with /use_sim_time=True but the error
> still persist.
>
> TF error:
> Node: /scan_assembler
> Time: 1275001492.698066055
> Severity: Warn
> Location:
> /opt/ros/cturtle/stacks/geometry/tf/src/tf.cpp:Transformer::setTransform:179
> Published Topics: /rosout
>
> TF_OLD_DATA ignoring data from the past for frame /sensor_mount_link
> at time 1.275e+09 according to authority /play_1280258731455287347
> Possible reasons are listed at
>
> My launch file for laser_assembler:
> <launch>
> <node pkg="laser_assembler" type="point_cloud_assembler"
> name="scan_assembler">
> <remap from="scan" to="tilt_scan"/>
> <param name="fixed_frame" value="base_footprint"/>
> </node>
> </launch>
>
>
>
> [1]
> http://www.ros.org/wiki/laser_assembler/Tutorials/HowToAssembleLaserScans
> --
> Hai Nguyen
> CS, Robotics
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>
--
Tully Foote
Systems Engineer
Willow Garage, Inc.
tfoote@willowgarage.com
(650) 475-2827
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