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chessboard not found while calibrating camera

asked 2014-02-21 10:05:07 -0500

synthnassizer gravatar image

updated 2014-02-22 06:09:12 -0500

berak gravatar image

Hi all, I am attempting to run chessboard calibration. the image of the chessboard can be found here:

http://postimg.org/image/w0k0ymgo3/

unfortunately the findCorners function does not identify the chessboard as seen in this image.

I don't know what could be the problem.

do you have any pointers / suggestions as to what I can try? Thank you..

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it needs more white border around it ( like the size of one square ) . and you got your fingers on the border even.

berak gravatar imageberak ( 2014-02-24 02:40:43 -0500 )edit

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answered 2014-02-24 02:34:06 -0500

jensenb gravatar image

First thing to be clear, there is no perfect calibration board detector, so that even with the right settings in OpenCV etc. there is no guarantee that OpenCV will always detect the calibration board although it is present in the image.

That aside, you should verify that your board settings are correct, make sure you have the right number of rows and columns etc. Besides I noticed there is a shading gradient across the board, as if it was being illuminated with a single point light source. This is not a good idea with the OpenCV chessboard detector. I have noticed it is sensitive to the relative difference between white and black tiles, if the difference is too low, i.e. because of poor illumination, it will not detect the board. I suggest you take images of your calibration pattern in a room with plenty of ambient illumination.

Last but not least, in the image it is apparent that your calibration pattern is not flatly attached to the board. This should really be fixed. The camera calibration routines assume that the board is perfectly planar, when this constraint is violated your calibration results will be arbitrary, they may be good, but they may also be poor.

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answered 2014-02-22 06:02:56 -0500

Here's a link to do camera calibration: Camera Calibration

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Asked: 2014-02-21 10:05:07 -0500

Seen: 1,906 times

Last updated: Feb 24 '14