iPhone reprojection error

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I tried to calibrate my iPhone using three different methods, ArUco, ChArUco, and chessboard. In all, I can't get a re-projection error better than 0.95. which is quite weird.

I checked the projected points and eliminated the ones that seem not correct, but nothing changed.

I have also gone through all the posts about this issue, but none has helped.

Any clue?