Thanks for your help. I now have a single node synchronizing my two cameras (image and infos). It works with the stereo_view and I get the disparity map, which I am configuring. My question is now about rviz, which I've never used. It seems to need a fixed frame to display my 3D cloud points. I tried to set a frame_id in my synchronization node (before broadcasting it to stereo_image_proc), but it does not work, rviz still can't get any fixed frame. How can I do that ? I think I am close to the result, but I can't see it ! Le mardi 18 mai 2010 à 09:07 -0700, Blaise Gassend a écrit : > Hi Sacha, > > stereo_image_proc doesn't care about when your message was published, it > just cares about the timestamp in the message. So your republishing node > needs to set the timestamp, both in the image topic and in the > camera_info topic. > > Blaise > > On Tue, 2010-05-18 at 16:29 +0100, 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 > > > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users