Circle pattern or chessboard for calibration?

asked 2018-12-19 21:31:05 -0500

joyuer gravatar image

updated 2018-12-21 07:38:47 -0500

Hello guys!

I've been reading a paper, Which Pattern? Biasing Aspects of Planar Calibration Patterns and Detection Methods, it says "two popular checkerboard and circular dot patterns are each examined with two detection strategies for invariance to the potential bias from projective transformations and nonlinear distortions. It is theoretically and experimentally shown that circular patterns can potentially be affected by both biasing sources. Guidelines are given to control such bias. In contrast, appropriate chessboard detection is shown to be bias free." which indicates that from this aspect chessboard is better than circular dot while both are used to calibrate the camera.

But, in another book, Learning OpenCV 3 By Gary Bradski, Adrian Kaehler, it is explicitly mentioned that circular dots are preferred these days. image description

Thus, these two contradictory statements make me kind of confused. Known that the paper mentioned above has been published a decade ago, if its conclusion has been widely accepted, did OpenCV function "findChessboardCorners()" and "findCirclesGrid()" solved the bias problems it proposed? Or it is just because I misunderstood one, or potentially the two statements?

Thanks for answering my question!

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It is hard to see what they mean by bias since the paper is not in open access.

Typically, with chessboard grid, there can be small uncertainties to locate the corners locations. With grid pattern, the circle center can be more accurately extracted using for example the center of gravity of all the circle pixels.

Eduardo gravatar imageEduardo ( 2018-12-20 08:59:15 -0500 )edit

I think that you can get this paper by the link I offered no? The author informed that the photo has already been distorted before calibration. So actually we could not extracted "accurately" the corner of chessboard or the center the circle. I've read that from others' work that circle performs better just like you said, but this paper tells that chessboard is more likely bias free.

joyuer gravatar imagejoyuer ( 2018-12-20 20:22:34 -0500 )edit

It is a paid link for me but here a direct link.

Eduardo gravatar imageEduardo ( 2018-12-21 07:25:14 -0500 )edit

Thanks for providing this link, I will update mine in the description :)

joyuer gravatar imagejoyuer ( 2018-12-21 07:38:13 -0500 )edit

Is it really an answer to your question ?

LBerger gravatar imageLBerger ( 2018-12-22 05:00:36 -0500 )edit

I don't think so : (

joyuer gravatar imagejoyuer ( 2018-12-22 06:09:55 -0500 )edit