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camera_calibration: checkerboard target not found [closed]

asked 2012-08-15 08:44:07 -0600

updated 2013-01-24 01:09:52 -0600

Hello everyone!

I am having a really hard time calibrating my Videre Design stereo cameras within ROS. My driver node is publishing the appropriate CameraInfo and Image messages, but the calibration tool is never able to find the checkerboard pattern.

I have tried better illumination and even printed targets of different sizes. What could I be doing wrong? Is there any chance my driver node is not behaving as expected?

I tried to use the videre_stereo_cam package initially, but I was never able to get it to work. So I simply wrote a wrapper node for the SVS (Small Vision System, by SRI International) libraries we used prior to ROS and, as far my judgement goes, it is working perfectly fine.

Thanks for your attention!

EDIT: Turns out the problem was with the definition of the size parameter of camera_calibrator. OpenCV expects the number of inner corners, not the number of squares. That was quite misleading and I was only able to figure that out after reading this.

I suggest the documentation and/or tutorials are more explicit about that. OpenCV documentation is quite clear about how cvFindChessboardCorners works), but the user of camera_calibration won't know that function is used until they open the source code.

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Closed for the following reason the question is answered, right answer was accepted by georgebrindeiro
close date 2012-09-05 19:07:03

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Could you post some pictures from your camera in which the checkerboard can't be detected?

Dan Lazewatsky gravatar imageDan Lazewatsky ( 2012-08-15 10:42:53 -0600 )edit

Sure thing! I will post them here as soon as I get back to the lab tommorow.

georgebrindeiro gravatar imagegeorgebrindeiro ( 2012-08-15 17:04:14 -0600 )edit

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answered 2012-09-05 19:06:45 -0600

Turns out the problem was with the definition of the size parameter of camera_calibrator. OpenCV expects the number of inner corners, not the number of squares. That was quite misleading and I was only able to figure that out after reading this.

I suggest the documentation and/or tutorials are more explicit about that. OpenCV documentation is quite clear about how cvFindChessboardCorners works), but the user of camera_calibration won't know that function is used until they open the source code.

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I also spent today struggling with this. Its rather exact too. A 9x9 checkerboard would require a 8x8, searching for a smaller 8x7 would fail.

rukie gravatar imagerukie ( 2019-09-19 16:18:14 -0600 )edit

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Asked: 2012-08-15 08:44:07 -0600

Seen: 1,462 times

Last updated: Jan 24 '13