The explanation of each step in ellipse fitting code

Question

Walaa 2023-4-6

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https://ww2.mathworks.cn/matlabcentral/answers/1942314-the-explanation-of-each-step-in-ellipse-fitting-code

评论： Matt J 2023-4-6

I need help understanding each line of this code.

% Calculate centroid, orientation and major/minor axis length of the ellipse
s = regionprops(BW,{'Centroid','Orientation','MajorAxisLength','MinorAxisLength'});
% Calculate the ellipse line
theta = linspace(0,2*pi);
col = (s.MajorAxisLength/2)*cos(theta);
row = (s.MinorAxisLength/2)*sin(theta);
M = makehgtform('translate',[s.Centroid, 0],'zrotate',deg2rad(-1*s.Orientation));
D = M*[col;row;zeros(1,numel(row));ones(1,numel(row))];

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Answer 1

Matt J 2023-4-6

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https://ww2.mathworks.cn/matlabcentral/answers/1942314-the-explanation-of-each-step-in-ellipse-fitting-code#answer_1210299

编辑：Matt J 2023-4-6

在 MATLAB Online 中打开

I've added some comments.

% Calculate centroid, orientation and major/minor axis length of the ellipse
s = regionprops(BW,{'Centroid','Orientation','MajorAxisLength','MinorAxisLength'}); 
theta = linspace(0,2*pi);
col = (s.MajorAxisLength/2)*cos(theta);
row = (s.MinorAxisLength/2)*sin(theta); %coordinates of points (col,row) on unrotated ellipse
M = makehgtform('translate',[s.Centroid, 0],'zrotate',deg2rad(-1*s.Orientation)); %rotation matrix
D = M*[col;row;zeros(1,numel(row));ones(1,numel(row))];%points on rotated ellipse