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Increased Reprojection Error from Chessboard Calibration

asked 2017-02-25 06:54:28 -0500

n.argirop gravatar image

So, I have written a script that performs chessboard calibration and the reprojection error I get is always greater than 1.3-1.5 pixels, even though the calibration parameters are correct (except the principal point coordinates, but that's expected). I couldn't find a reason why this is happening and then I thought to try it by photographing the target with lower camera resolution, since many of the forum threads I found were talking about less than 0.5 pixel error with low resolution cameras (640x480 pix) and I was using DSLRs with 6-7 times this resolution. After this attempt the error was indeed lower than 1 pixel but still a little too high. Then, I downsampled the images to 640x480 resolution and the error now had the expected and desired values of less than 0.4-0.5 pixels. Any ideas why this is happening?

P.S. The script is written in Python and I am using subpixel refinement for the detected chessboard corners.

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answered 2018-03-06 08:53:38 -0500

abhijit gravatar image

It is hard to say, Your question misses a lot of information. But check out this small python API to calibrate the camera. I have used it to calibrate the camera on chessboards of size 2590 x 1942 and I regularly get less than 0.3 pixels.

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Asked: 2017-02-25 06:54:28 -0500

Seen: 479 times

Last updated: Mar 06 '18