Perform angle recognition on the objects in the following images

Question

tao wang 2022-3-17

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1673634-perform-angle-recognition-on-the-objects-in-the-following-images

评论： tao wang 2022-3-17

clc
clear
A = imread('shipai.jpg');
A = rgb2gray(A);
BW = A<128;
% find angle of dominant line
[H,T,R] = hough(BW);
P  = houghpeaks(H,5,'threshold',ceil(0.3*max(H(:))));
x = T(P(:,2)); y = R(P(:,1));
plot(x,y,'s','color','white');
lines = houghlines(BW,T,R,P,'FillGap',5,'MinLength',7);
imshow(A), 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
n = length(lines);
for i=1:n-1
    k=(lines(i).theta-lines(i+1).theta);
    if abs(k>=15)
        jiaodu=k
        return
    end
end

That's the code I used originally. It has a good effect on the following image recognition

Then you can get that the angle of two of the lines is 90

But for the following pictures, we can't recognize straight lines very well

I can't recognize the boundary straight line very well. The main reason is that my camera is not very good and the fabric is a little reflective. Is there any better way to deal with it? Thank you

4 个评论
显示 2更早的评论隐藏 2更早的评论

Image Analyst 2022-3-17

I've spent about a third or half my working career over the past 30 years working on fabric image analysis. There are many papers published on it. See this link:

http://www.visionbib.com/bibliography/applicat840.html

tao wang 2022-3-17

Thank you very much. I will study hard

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Simon Chan 2022-3-17

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1673634-perform-angle-recognition-on-the-objects-in-the-following-images#answer_919904

编辑：Simon Chan 2022-3-17

在 MATLAB Online 中打开

fabric.png

Do some filtering before searching for lines.

Need to increase the number of peaks to 20 for function houghpeaks otherwise it is not possible to detect the diagonal line.

clear; clc;
rawdata = imread('fabric.png');
A = rgb2gray(rawdata);
se = strel('square',3);
BW1 = imbothat(A,se);                           % Filtering
BW2 = bwareaopen(BW1>2,5);                      % Remove small objects
% find angle of dominant line
[H,T,R] = hough(BW2);
P  = houghpeaks(H,20,'threshold',ceil(0.3*max(H(:))));  % Increase number of peaks = 20
x = T(P(:,2)); y = R(P(:,1));
plot(x,y,'s','color','white');
lines = houghlines(BW2,T,R,P,'FillGap',5,'MinLength',7);
imshow(A), 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
n = length(lines);
for i=1:n-1
    k=(lines(i).theta-lines(i+1).theta);
    if abs(k>=15)
        jiaodu=k
        return
    end
end

4 个评论
显示 2更早的评论隐藏 2更早的评论

Simon Chan 2022-3-17

You may extend the line manually from the result in variable 'lines'.

tao wang 2022-3-17

Thank you. I used the parameter equation of two points to calculate the intersection with the picture, but it's more troublesome if the denominator is equal to 0. Thank you. I'll try again

请先登录，再进行评论。