I am trying to find the corners of the "rectangular" shapes. This code is working very well. But I dont know exactly how it works. Can you explain me ??

Question

ahmet ilhan 2018년 8월 1일

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https://kr.mathworks.com/matlabcentral/answers/413079-i-am-trying-to-find-the-corners-of-the-rectangular-shapes-this-code-is-working-very-well-but-i-d

답변: jim as 2021년 1월 14일

[I,J] = find(binaryimg>max(binaryimg(:))/2);
IJ = [I,J];
[~,idx] = min(IJ*[1 1; -1 1; 1 -1; -1 -1].');
Corners = IJ(idx,:);

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Answer 1

Matt J 2018년 8월 1일

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https://kr.mathworks.com/matlabcentral/answers/413079-i-am-trying-to-find-the-corners-of-the-rectangular-shapes-this-code-is-working-very-well-but-i-d#answer_331199

편집: Matt J 2019년 4월 14일

Maybe this image will help. The corners of a polyhedron will maximize/minimize the intercept of lines of a certain slope - it's a linear programming principle. In the code shown, the lines used x+y, x-y, -x+y,-x-y are those oriented at 45 degrees to the x,y axes. As long as the rectangle edges are approximately parallel/perpendicular to the x,y axes, its corners will minimize the intercept of one of these lines.