how I extract all straight line co-ordinates from hough transform ?

Question

sufian ahmed 2017-5-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/341588-how-i-extract-all-straight-line-co-ordinates-from-hough-transform

回答： KSSV 2017-5-24

After hough transform I get some horizontal lines. I want to read this horizontal line data , for example: co-ordinates of those lines. Here is the code :

BW=imread('a.png');
[H,theta,rho] = hough(BW);
% figure
% imshow(imadjust(mat2gray(H)),[],...
%        'XData',theta,...
%        'YData',rho,...
%        'InitialMagnification','fit');
% xlabel('\theta (degrees)')
% ylabel('\rho')
% axis on
% axis normal 
% hold on
% colormap(gca,hot);
P = houghpeaks(H,10,'threshold',ceil(0.5*max(H(:))));
% x = theta(P(:,2));
% y = rho(P(:,1));
% plot(x,y,'s','color','black');
lines = houghlines(BW,theta,rho,P,'FillGap',50,'MinLength',20);
figure, imshow(BW), 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 beginnings and ends of lines
   plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');
   plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');
   % Determine the endpoints of the longest line segment
   len = norm(lines(k).point1 - lines(k).point2);
   if ( len > max_len)
      max_len = len;
      xy_long = xy;
   end
end
% highlight the longest line segment
plot(xy_long(:,1),xy_long(:,2),'LineWidth',2,'Color','red');