How can I find the droplet contact angle of the image using hough transform to determine the boundaries? The code gives me droplet contact angle 0. But I want to calculate the angle the contact surface makes with the bubble.

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Albert Hagan 2017-7-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/348293-how-can-i-find-the-droplet-contact-angle-of-the-image-using-hough-transform-to-determine-the-boundar

评论： Image Analyst 2017-7-11

hydrophobe1.jpg

在 MATLAB Online 中打开

Irgb = imread('hydrophobe1.jpg'); Igray = rgb2gray(Irgb); BW = edge(Igray,'canny'); [H,theta,rho] = hough(BW);

figure; imshow(imadjust(mat2gray(H)),[],... 'XData',theta,... 'YData',rho,... 'initialmagnification','fit'); colormap(gca,hot);

P = houghpeaks(H,5,'threshold',ceil(.7*max(H(:))));

lines = houghlines(BW,theta,rho,P,'Fillgap',5,'Minlength',7); figure, imshow(Igray), hold on max_len = 0; for k = 1:length(lines); xy = [lines(k).point1; lines(k).point2]; plot(xy(:,1),xy(:,2),'linewidth',2,'color','green');

    plot(xy(1,1),xy(1,2),'x','linewidth',2,'color','green');
    plot(xy(2,1),xy(2,2),'x','linewidth',2,'color','red');
    len = norm(lines(k).point1 - lines(k).point2);
    if (len > max_len)
        max_len = len;
        xy_long = xy;
    end
end
plot(xy_long(:,1),xy_long(:,2),'Linewidth',2,'Color','Red');

x1 = xy_long(1); x2 = xy_long(2); x3 = xy(1); x4 = xy(2);

y1 = xy_long(3); y2 = xy_long(4); y3 = xy(3); y4 = xy(4);

theta1 = atan((y1-y2)/(x1-x2)) theta2 = atan((y3-y4)/(x3-x4)) ThetaFinal = abs((theta1-theta2)*(180/pi)

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Image Analyst 2017-7-11

What is the difference in your mind between the "contact angle" (which you say your code computes) and the "angle the contact surface makes with the bubble" (which you say you need)??? Please attach diagram with lines and angles indicated on it. Read this too.

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