Calculate percentage of similarities in two polygons

% Some example polygons
theta = linspace(0, 2*pi, 100);
x1 = cos(theta) - 0.5;
y1 = -sin(theta);  
x2 = x1 + 1;
y2 = y1;
% Calculate
[xint, yint] = polybool('&', x1, y1, x2, y2);
[xun,  yun]  = polybool('|', x1, y1, x2, y2);
a1 = polyarea(xun, yun);
a2 = polyarea(xint, yint);
sim = 1 - (a1- a2)./a1;

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Amaral 2015-11-10

编辑：Amaral 2015-11-10

It worked very well. It gives accurate results which is exactly what i'm looking for. Thanks :)

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Answer 2

Image Analyst 2015-11-9

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https://ww2.mathworks.cn/matlabcentral/answers/253944-calculate-percentage-of-similarities-in-two-polygons#answer_199106

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If that definition works for you, then that's fine. One could think of others, but whatever works for what you need it to, is fine. I think the easiest way to solve the formula is to convert the polygons to images with poly2mask().

rows = 1920; % Whatever is needed to contain your points.
columns = 1600;
image1 = poly2mask(x1,y1, rows, columns);
image2 = poly2mask(x2,y2, rows, columns);
unionImage = image1 & image2;
intersectionImage = xor(image1, image2)
similarity - 1 - (sum(unionImage(:) - intersectionImage(:)) / sum(unionImage(:));

If your x and y are too small, then multiply them by some scaling factor beforehand, like 100 or 1000 or whatever so that your image is big and not too pixelated.

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Amaral 2015-11-9

Thanks for the answer. :) I'll try it out :)

Amaral 2015-11-9

编辑：Amaral 2015-11-9

在 MATLAB Online 中打开

Your approach worked. But had to do some adjustments because i think the way you calculated the union and intersection is wrong. This way it gives the results i want, at least i think so according to the results in the tests :P

unionImage = image1 | image2;
intersectionImage = image1 & image2;
similarity = (1 - (sum(unionImage(:) - intersectionImage(:)) / sum(unionImage(:)))) * 100

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