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fit a circle to a cloud of points

asked 2020-03-17 08:49:50 -0500

SylvainArd gravatar image

Hi, how to fit a circle with a cloud of points which can only represent a quarter of the circle ? Thank you

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RANSAC could be the solution. Each triplet of points(random selected 3 points from cloud). Made a prediction of the circle. Then check if this prediction is good for you(e.g. check how many points lay in some tolerance from this circle{arc} ) https://en.wikipedia.org/wiki/Random_...

When you have a prediction. Use cv::fitEllipse https://docs.opencv.org/2.4/modules/i...

Or DownHillSolver to fit it. https://docs.opencv.org/3.4/d4/d43/cl...

Jony01 gravatar imageJony01 ( 2020-03-17 11:41:30 -0500 )edit
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Find the centre, then find the most distant point from that centre. Voila, you have your centre point and radius.

sjhalayka gravatar imagesjhalayka ( 2020-03-17 14:34:35 -0500 )edit

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answered 2020-03-17 13:53:02 -0500

exbigboss gravatar image

You can always brute-force it, calculating the maximum distance between any two points in the cloud. This should give you the diameter of the circumcircle. I'm not sure what "quarter of the circle" means, however.

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Maximal distance is not a diameter !!!

Jony01 gravatar imageJony01 ( 2020-03-18 03:22:04 -0500 )edit

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Asked: 2020-03-17 08:49:50 -0500

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Last updated: Mar 17 '20