How to apply two polygon on two outlines

Question

Jórdan Venâncio Leite 2020-4-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/515626-how-to-apply-two-polygon-on-two-outlines

评论： Rena Berman 2020-10-12

I have two images. The objective is to find the area of the approximation made by polygons in the contours of the images.

In the first image i drew a polygon and it gave me a satisfactory approximation of the contour (bellow) and thus I was able to obtain its area through the 'polyarea' function.

I would like to apply the same to the second image, where there are two outlines. I would like to obtain the area of the approximation made by two polygons in these two contours.

How could I change my code to achieve this effect?

Thanks in advance.

clc
clear 
close all
skip = 320;
load('Image.mat');
image = preenc;
% Identify  the contours and its areas
Contours = bwconncomp(preenc, 8);
area = regionprops(Contours, 'Area');
figure, imshow(preenc);
% Speeds up the use of boundary later
Bperimeter = bwperim(preenc);
Bperimeter = imdilate(Bperimeter,strel('square',4));
% Get x,y coordinates of perimeter (column index and row index,
% respectively)
[y,x] = find(Bperimeter);
k = boundary(x,y,1); %use boundary with shrink factor of 1 to find vertices
% Back to the initial binary image, add the polygon using recently
% obtained vertices
idx = [k(1:skip:end);k(1)];
drawpolygon('Position',[x(idx) y(idx)])
% Calculate the area of the polygon
d = polyarea(x(idx),y(idx));
disp(d)

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Rena Berman 2020-10-12

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Answer 1

Ameer Hamza 2020-4-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/515626-how-to-apply-two-polygon-on-two-outlines#answer_424234

在 MATLAB Online 中打开

Try this

clc
clear
close all
skip = 50;
load('image2.mat');
image = preenc;
% Identify  the contours and its areas
Contours = bwconncomp(preenc, 8);
area = regionprops(Contours, 'Area');
figure, imshow(preenc);
for i=1:Contours.NumObjects
    image_ = image;
    % hide all other patches
    mask = zeros(size(image));
    mask(Contours.PixelIdxList{i}) = 1;
    image_(~mask) = 0;
    
    % Speeds up the use of boundary later
    Bperimeter = bwperim(image_);
    Bperimeter = imdilate(Bperimeter,strel('square',4));
    % Get x,y coordinates of perimeter (column index and row index,
    % respectively)
    [y,x] = find(Bperimeter);
    k = boundary(x,y,1); %use boundary with shrink factor of 1 to find vertices
    % Back to the initial binary image, add the polygon using recently
    % obtained vertices
    idx = [k(1:skip:end);k(1)];
    drawpolygon('Position',[x(idx) y(idx)])
    % Calculate the area of the polygon
    d = polyarea(x(idx),y(idx));
    disp(d)
end