Why April tags are better than chess pattern for camera calibration? Why it gives different camera matrix? I have already used calibration via chess pattern and made it another time with April tags and both gave me two different camera matrix. The different wasn't so big, but still ? Why it exists at all?
1 Answers
The intuition is as follows: The camera calibration is applied on all corners identified in the raw images. In order to maximize the ROI we want to capture corners in the peripheral areas of the image (where the distortion is most extreme). In the raw image peripherals the MTF is low, which makes the corner detection less reliable, and arucos (april tags) can be used in order to improve the corner detection in those regions.
As a rule of thumb: in fiseye lens, it's is helpfull to use april tags.
If you use a regular checkerboard calibration wioth a fisheye lens, the sub-pixels corner detection will not be as accurate in the peripherals and the reprojection error will be higher.
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