Sacha, Check if you are publishing/filling in the timestamps in the header, and whether they are the same for both images. Another solution for your problem is to write a node that uses an approximate time synchronizer to get the images, and then re-publishes them again to stereo_image_proc. Cheers, Radu. On 05/18/2010 08:29 AM, Sacha Aury wrote: > I think that having a hardware solution is a bit overkill for my > problem. So I tried to write a node which collected image messages from > my two cameras and which published both message every x seconds, > typically 1/2. And when I am using image_pipeline/stereo_image_proc, I > got messages of that kind : > > [ WARN] 1274196325.866264000: [stereo_image_proc] Low number of > synchronized left/right image pairs received. > Left images received: 831 > Right images received: 831 > Synchronized pairs: 0 > Possible issues: > * The cameras are not synchronized. > * The network is too slow. For each synchronized image pair, at most 1 > is getting through. > > I don't know what I could do more, since the synchronisation should be > done by a TimeSynchronizer in the stereo_image_proc class. Could it be > posible to cheat on the timestamps in any way ? > > Thanks, and sorry for the double post, I made a mistake at first. > > Le lundi 17 mai 2010 à 07:53 -0700, Gary Bradski a écrit : >> What level do you want synchronization on? Within framerate (both >> frames happen randomly but within 1/30 of a second of each other) or >> exact frame synchronization? The first is achievable, the second needs >> extra hardware. >> >> At most, ROS can get you timestamps to align to, but to get actual >> simultaneous frames, you'll need a triggering signal in hardware such >> as a wire between 2 cameras (that allow for this). Some 1394 cameras >> may allow triggering over the 1394 bus and then you'll only have the >> problem of getting both buses to trigger at the same time ... which >> may be approximately possible, most of the time ... on average. >> Depends on the driver and the 1394 port. >> >> I've seen an automotive 1394 article (not ROS related) where they have >> about 10 cameras. The cameras run the cameras at very high framerates >> and then they do timestamp synchronization which allows fairly >> synchronous alignment of multiple with no extra hardware. >> >> Gary >> >> On Mon, May 17, 2010 at 5:23 AM, Sacha Aury >> wrote: >> Hi, >> >> I am trying to make a stereo camera acquisition using ROS with >> the >> cameradc1394 driver and the stereo_proc package. I've got a >> separate >> computer to stream the image_raw from my two cameras. The >> stream works, >> but when I launch stereo_image_proc, it seems that my two >> cameras are >> not synchronized : >> >> [ WARN] 1274098675.074074000: [stereo_image_proc] Low number >> of >> synchronized left/right image pairs received. >> Left images received: 3079 >> Right images received: 3076 >> Synchronized pairs: 0 >> Possible issues: >> * The cameras are not synchronized. >> * The network is too slow. For each synchronized image >> pair, at most 1 >> is getting through. >> >> Here is my launch file : >> >> >> >> >> >> >> >> > type="cameradc1394" >> respawn="true"> >> > value="/stereo/left/"/> >> >> >> >> >> > type="cameradc1394" >> respawn="true"> >> > value="/stereo/right/"/> >> >> >> >> >> >> Is there any specific way to make the two cameras >> synchronize ? >> >> I am following that tutorial : >> >> http://www.ros.org/wiki/stereo_image_proc >> >> Thank you for any help. >> >> Sacha >> >> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users >> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users > > > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users -- | Radu Bogdan Rusu | http://rbrusu.com/