how get centroid contour distance every 1 degrees?

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Robin 2014-6-10

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回答： LOKESH KAVULURU 2017-4-5

pict.png

I have an image and I already get the boundary and the weighted centroid of region of interest. I want to get the coordinate point of boundary at certain degrees. It starts from the fartest distance of center to edge and its counterclockwise.  I have tried, using bwboundaries but the result is not appropriate with my goal. Can anyone help me about this? Thx for the help

this is my code

    % BW = imread('fyc-00_1-006.png');
BW1 = bwareaopen(BW, 1000);                        
BW2 = imfill(BW1, 'holes');   
s  = regionprops(BW, 'centroid');
centroids = cat(1, s.Centroid);
[meanx,meany] = ait_centroid(BW2);
meanx;
meany;
[B,L,N,A] = bwboundaries(BW2);
imshow(BW2); hold on;
for j=1:N,
    if(~sum(A(j,:)))
       thisboundary = B{j};
       plot(thisboundary(:,2),...
           thisboundary(:,1),'r','LineWidth',2);
       for l=find(A(:,j))'
           thisboundary = B{l};
           plot(thisboundary(:,2),...
               thisboundary(:,1),'g','LineWidth',2);
       end
    end
end
plot(centroids(:,1), centroids(:,2), 'b*');
title('Binary Image', 'FontSize',20);
axis on;
x = thisboundary(:,2);                  %Column
y = thisboundary(:,1);                  %Rows
deltaY = y - meany;
deltaX = x - meanx;
distances = sqrt((x - meanx).^2 + (y - meany).^2);
<</matlabcentral/answers/uploaded_files/13965/pict.png>>

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Answer 1

Image Analyst 2014-6-10

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What is "ait_centroid"? It's not defined anywhere. Also, you're not calculating the angles of the boundary coordinates to the centroid or weighted centroid. You said you did it but didn't show how you did it. I don't see any reason why that should not work.

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Robin 2014-6-10

在 MATLAB Online 中打开

ait_centroid is a function that I used to find centroid point. This is my code to calculate angles of boundary

    % xCenter = meanx;
yCenter = meany;
angles=zeros(length(y),1);
for j = 1 :length(y)
    angle = atand(abs(deltaY(j) ./ deltaX(j)));
    % Convert to 0-360
  if y(j) <= yCenter && x(j) >= xCenter
    angles(j) = angle;
        quadrant = 1;
  elseif y(j) <= yCenter && x(j) <= xCenter
    angles(j) = 180 - angle;
    quadrant = 2;
  elseif y(j) >= yCenter && x(j) <= xCenter
    angles(j) = 180 + angle;
    quadrant = 3;
  elseif y(j) >= yCenter && x(j) >= xCenter
    angles(j) = 360 - angle;
    quadrant = 4;
    end

end

please help me how to find the coordinate point of boundary every one degrees and It starts from the fartest distance of center to edge and its counterclockwise.

Image Analyst 2014-6-10

That's not exactly how I'd do it. First tell me what is a typical angle you'd want to find the boundary coordinate closest to? 20 degrees? 45 degrees? Something else?

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