find the wheel centre and radius in pixel
in [Matlab]
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From: Benson on 14 Jun 2010 10:17 here is my wheel pic http://i47.tinypic.com/k06jib.jpg how can I find the centre and radius for the wheel(size of wheel) only the steel(what) part of wheel,not include tyre. I've been try to used the Detect circles with various radii in grayscale image via Hough Transform but not really work, can someone please help me? This is really important for me. Thank you.
From: ImageAnalyst on 14 Jun 2010 11:00 "Benson " <popo2...(a)gmail.com>: In short, threshold, bwlabel(), and finally regionprops() to measure the centroid of the largest blob. Here's a demo where I do the same thing except with coins instead of a wheel: http://www.mathworks.com/matlabcentral/fileexchange/25157 If it turns out that the bright stuff touching the edge of the image is the largest blob, then get rid of it by calling imclearborder() before you call bwlabel(). Good luck, ImageAnalyst
From: ImageAnalyst on 14 Jun 2010 11:04
I forgot to mention that you can calculate the major and minor axis lengths also with regionprops, or if you want to assume that it's perfectly circular, you can calculate the ECD (equivalent circular diameter) (area of circle) = pi * (diameter^2)/4 ECD = sqrt(4*area/pi); % A very common metric that people measure. ECR = ECD/2; % The equivalent circular radius. |