Incorrect result from camera calibrator app
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cr
on 18 Mar 2024
Edited: Alexander Groeger
about 5 hours ago
I used the camera calibrator app to calibrate lens distortion and I specified correct checkerboard size of 8mm. The calibration goes fine and i'm able to undistort images and points. However, the plot from showextrinsics() shows camera at 8mm distance from object but in reality it is 140mm. Why is this wrong?
My setup has a camera looking downwards and pattern is placed at the same working distance in all 30+ images where the lens is focused.
Calibration settings: All default settings - Standard lens, 2 coeffs, no tangential distortion, no skew, etc.
4 Comments
Giridharan Kumaravelu
on 19 Mar 2024
Would you mind providing us with the calibration images to help troubleshoot this behavior?
Accepted Answer
Giridharan Kumaravelu
on 22 Mar 2024
Edited: Giridharan Kumaravelu
on 22 Mar 2024
Thanks for providing the calibration images. This is a limitation of the technique (Zhang's algorithm) that camera calibrator app uses, that it cannot calibrate a camera with calibration images that are coplanar. To accurately calibrate a camera with the app, you need some variance in the calibration images in the z-direction. Even a little wiggle in the z direction could avoid this degenerate configuration.
4 Comments
Alexander Groeger
about 6 hours ago
Edited: Alexander Groeger
15 minutes ago
How exactly is the use of the camera calibrator intended in the case of a telecentric camera?
Thanks in advance.
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