rosbag recording pointclouds

asked 2011-09-30 01:59:31 -0500

kang
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updated 2012-01-05 05:14:03 -0500

58457 ●128 ●550 ●526 http://www.ros.org/

Hi, I am using rosbag in rosdiamonback for recording pointcoulds sequences (video). So far, I feel it could not provide smooth running video, there is always lagging or even lost on some frames. While recording on images give nice smooth video from frame to frame, at least no obvious lost frames. I am wondering if it is the problem from the rosbag itself for pointclouds recording or I am missing something.

If someone has alternative solution for pointcloud sequences recording, pls let me know.

Best, Kang

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Are you recording on the same machine in which the video is taken?

DimitriProsser ( 2011-09-30 02:08:29 -0500 )edit

yes. Btw, I check using rosinfo and notice there is no much lost frames. It's still between 25-30 frames/s. But, when viewing with rosbag play on rviz, it looks there's a lot of frames lost.

kang ( 2011-10-02 20:50:42 -0500 )edit

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answered 2011-10-03 23:27:51 -0500

Lorenzo Riano
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Pointclouds are extremely demanding in terms of bandwidth and space usage. I am surprised to see that you are recording at full frame rate. Unless you really have a fast computer (at least an I7 processor) you will have problems running rosbag play on a pointcloud bag and rviz on the same machine.

You should have a look at various pointcloud compress packages, for example:

Compressed Pointcloud transport
pointcloud_compress This is very simple as pubishes a zipped message, and it has the unzipper as well. The power of Python!

As a rule of thumb, always try to save the pointcloud from the same computer it is producing it, and load it from the same computer it is processing it.

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Hi, thanks for comment. I did some experiments and recording again. Now, I am still not sure where the problem the problem exists, whether when recording or when playing. using rosinfo, I got AVERAGE frame/s can be 20frames/s. While playing I notice the frequency of frame/s is not stable.

kang ( 2011-10-11 02:04:35 -0500 )edit

Regarding the two compress packages you mention, could you pls tell a little more what they do (or maybe link) since the links doon't provide any information.

kang ( 2011-10-11 02:05:37 -0500 )edit

I only know the second package, as I co-develop it. The source code is very short and readable. There are two scripts: compress.py takes a /camera/depth/points2 message, compresses it and outputs a message on '/camera/depth/points2_compressed'. decompress.py does the opposite.

Lorenzo Riano ( 2011-10-11 02:35:30 -0500 )edit

Neither seem to be part of ROS anymore (at least they are not indexed and the provided links don't work). Any advice what to do using a newer version of ROS (mine is Indigo)?

rbaleksandar ( 2015-08-14 11:03:36 -0500 )edit

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answered 2011-09-30 03:13:04 -0500

joq
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Tools like rostopic hz and rostopic bw are useful for determining how quickly your device is publishing data. If the bandwidth is too high, your system may be having trouble storing it fast enough.

You say the pointclouds are being recorded as video. With image_transport, compressed JPEG video can be recorded by appending /compressed to the topic name.

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Thanks for the comment. What I meant with video here is sequences of pointclouds, not 2D sequences. Yes, one of the thing I suspect now is that my machine is too busy while storing.

kang ( 2011-09-30 03:32:52 -0500 )edit

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rosbag recording pointclouds

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