[ros-users] problems with image_proc using a modified camera

David Feil-Seifer david.feilseifer at gmail.com
Thu Apr 8 00:29:33 UTC 2010

OK, CameraSubscriber and CameraPublisher worked. image_proc is working
now, thank you.


On Wed, Apr 7, 2010 at 4:15 PM, Eric Perko <wisesage5001 at gmail.com> wrote:
> David,
> It doesn't look like you are doing anything special to sync the
> timestamps in letterbox/image_raw and letterbox/camera_info. If they
> are out of sync, image_proc may not work properly. I've seen a mention
> of a special CameraPublisher class that can help you to do that (see
> http://www.ros.org/doc/api/image_transport/html/classimage__transport_1_1CameraPublisher.html).
> You should also take a look at
> http://www.ros.org/doc/api/image_transport/html/classimage__transport_1_1CameraSubscriber.html
> , as it might simplify gathering both the image_raw and camera_info
> topics.
> - Eric
> On Wed, Apr 7, 2010 at 6:51 PM, David Feil-Seifer
> <david.feilseifer at gmail.com> wrote:
>> I am trying to use image_proc to rectify an image which is just a
>> camera image that has a border added around. The purpose is to make a
>> rectified image that includes all of the image (including what does
>> not strictly fit into a square), not just the centermost part. To do
>> this I made a new node image_letterboxer (included source) to add the
>> border and to adjust the camera calibration cx and cy params to
>> reflect the new center of the image. This has worked when not using
>> image_proc to do the undistort.
>> However, when I try to use this node with image_proc, it does not work
>> at all. I dug a little into the source and found that the image
>> transport is subscribing to the new image topics correctly, and that
>> image transport is registering that subscription, but no callbacks are
>> being called. My image_letterboxer node works well enough so that
>> image_view can display the new image_raw topic with the letterboxed
>> image, but image_proc does not work, though it does work on the camera
>> itself.
>> I assume that the problem is in the image_letterboxer node, but I
>> cannot figure out what I did wrong. Is there some flaw in the way that
>> I'm using image_transport to publish the images? Or is there something
>> wrong with image_proc?
>> Thanks in advance,
>> -Dave
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