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Fisheye calibration image not detecting any corners

asked 2020-08-21 14:12:00 -0500

updated 2020-08-21 20:50:51 -0500

supra56 gravatar image

I have the following barrel-distorted fisheye image:

image description

And I am finding the corners in it using the findChessboardCorners function as follows:

cv2.findChessboardCorners(gray, CHECKERBOARD, cv2.CALIB_CB_ADAPTIVE_THRESH | cv2.CALIB_CB_FAST_CHECK | cv2.CALIB_CB_NORMALIZE_IMAGE)

However, I'm getting no corners, i.e., this function returns False, None. Why is that?

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-1

answered 2020-08-22 01:56:12 -0500

berak gravatar image

updated 2020-08-22 01:59:52 -0500

your image is not a valid chessboard (but some artificially rendered 3d cube (?) with a chessboard pattern), you cannot use it

please e.g. print out the one from here and take a real image with your camera

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-2

answered 2020-08-21 20:50:07 -0500

supra56 gravatar image

Change this:

cv2.findChessboardCorners(gray, CHECKERBOARD, cv2.CALIB_CB_ADAPTIVE_THRESH | cv2.CALIB_CB_FAST_CHECK | cv2.CALIB_CB_NORMALIZE_IMAGE)

to:

ret, corners = cv2.findChessboardCorners(gray, CHECKERBOARD, cv2.CALIB_CB_ADAPTIVE_THRESH + cv2.CALIB_CB_FAST_CHECK + cv2.CALIB_CB_NORMALIZE_IMAGE)
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Comments

supra, no, that's so silly !

berak gravatar imageberak ( 2020-08-22 01:57:59 -0500 )edit

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Asked: 2020-08-21 14:12:00 -0500

Seen: 180 times

Last updated: Aug 22 '20