[ros-users] camera_calibration

James Bowman jamesb at willowgarage.com
Wed Apr 7 17:24:52 UTC 2010

Right, for stereo to work it needs synchronized frames.  Our imaging
pipeline is based on this.

If the cameras are not synchronized, then recovering stereo information will
be hard.  One idea would be to detect the absence of movement in both frames
("Learning OpenCV" page 293), and emit synchronized frames when this
happens.  This could be done in the driver.

On Wed, Apr 7, 2010 at 9:53 AM, Blaise Gassend <blaise at willowgarage.com>wrote:

> With two threads this morning discussing calibration with unsynchronized
> cameras, I can't help wondering how well the camera_calibration code
> will work if the cameras aren't being triggered simultaneously. If
> camera_calibration decides to use a pair of frames in which the
> checkerboard was moving, I imagine that you might be trying to match
> checkerboards that were actually at different positions, which would
> certainly lead to poor calibration.
> I have no idea if this is a reasonable worry to have, and James could
> probably say more about this than I could. I imagine that motion blur
> would tend to discourage the use of frames in which the target is
> moving.
> On Tue, 2010-04-06 at 15:31 -0500, Patrick Beeson wrote:
> > I'm trying to calibrate two identical 1394 cameras that are sitting next
> > to each other.  The stereo calibration from camera_calibration converges
> > to VERY bad R and T matrices, rotating the frames and
> > the warping the images drastically.  I've tried several times, with no
> luck.
> >
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