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type and size of calibration pattern for most accurate results

asked 2013-08-25 08:59:10 -0500

efanucar gravatar image

Hi!

I want to use OpenCV for accurate measuring - so the first step should be the best camera calibration possible.
There are three types of camera calibration patterns:

  • chessboard
  • symmetric circles
  • asymmetric circles

Does anyone have some experience which type is the most accurate?
What is the advantage of sym and asym. circle pattern, if any?

Another important parameter is the relative size of the pattern in the camera image. Are there any rules for the minimum size? For example the pattern should cover 25% of the image or something like that?
Is there any minimum radius in pixels for the circles/width of the squares in the resulting image?

Thanks!

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The guys that wrote those calibration algorithms say that circles are far more accurate. But I cannot remember where they wrote that - I think in the Weekly Meeting Notes.

sammy gravatar imagesammy ( 2013-08-26 04:19:57 -0500 )edit

And did they mention which relative size the pattern should have in the final image? I guess if it's too small the calibration is only valid for small parts of the image and not for the whole covered area?

efanucar gravatar imageefanucar ( 2013-09-07 03:20:40 -0500 )edit

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answered 2013-08-26 02:36:06 -0500

engine gravatar image

Hi!

for the calibration I think the best thing is use the chessboard, because it's easier and faster to recognize then the circles, and try to use an asymmetric combination meaning a 7x8 or 13x10 etc ... to get the rotation information too. And after running the calibration you'll the calibration error the should as small as possible and it's the case if cover the whole size of your frame!

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Asked: 2013-08-25 08:59:10 -0500

Seen: 1,008 times

Last updated: Aug 26 '13