are your image_raw topics
synced? I'm trying to use two individual cameras, but because each one
gets its own camera1394 node, I don't think their timestamps will ever
really be in sync even with external triggering or some other
guarantee I can make about the frames themselves matching up.
This is most likely the problem. The stereo camera calibrator only subscribes to the image topics, not camera_info, but it does expect the left and right images to be synchronized. The wge100_camera driver goes to some trouble to support synching two cameras with an external trigger, and of course this is easy with a unified stereo camera that does the triggering for you.
The more lax case of trying to use two unsynchronized cameras for stereo isn't directly supported by the image_pipeline right now. message_filters is gaining support for approximate time synchronization, so maybe I should target that for the next image_pipeline release. It's better to have the cameras synchronized, but clearly that poses some technical problems.
A hacky workaround would be to write a relay node that listens to the left and right image topics, matches up pairs that are close enough, and republishes them with the same timestamp.
What is the behavior of the stereo camera calibrator if the left and
right image topics are not sycned up? Does it just hang waiting for a
synchronized pair?
Yep...
If so, it might be really helpful to get some sort
of warning that the two image topics are out of sync and therefore
will not be used.