correct quadrant and angle when not using roipoly

Question

slowlearner 2021-1-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/707038-correct-quadrant-and-angle-when-not-using-roipoly

编辑： slowlearner 2021-1-5

Hi I'm trying to make 2 objects in a picture the points of interest however, the problem I'm facing is that I can't get the angle of the point of interest. the simpler solution would be to do it with roipoly but then i wont understand the how...

The picture contains the 2 lego platforms I intend to mark as points of interests but when selecting the right one I get a square with the background table. So in the code I need to account for the angle, I'm trying to make all my codes more general purpouse hens the switch case i know i should implement it in a loop for more objects than two but that comes later at the moment i just need to solve this hurdle.

cam = webcam;
img_piece = snapshot(cam);
figure;imshow(img_piece);
hold on;
roi1 = drawpolygon;
mask1 = createMask(roi1);
draw(roi1);
mask2 = createMask(roi1);
mask = mask1 + mask2;
pause
maskedImg = img_piece;
for i = 1:size(img_piece,1)
    for j = 1:size(img_piece,2)
        if ~mask(i,j)
            maskedImg(i,j,:) = [0  0  0];
        end
    end
end
figure;imshow(maskedImg);
%% EDIT: the code now contains the correct answer but for multiple uses you need to make it your own

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Answer 1

Image Analyst 2021-1-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/707038-correct-quadrant-and-angle-when-not-using-roipoly#answer_589223

编辑：Image Analyst 2021-1-2

You need to use roipolyold() or drawpolygon() instead of all that with ginput(), etc.

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slowlearner 2021-1-5

I'm at a loss I just don't know how to "turn of" everything but the region drawn by the drawpolygon() function because i get a 4x2 array and don't know how to make that into the "area" if the angle is unknown. I guess i could work one out with cosinrule and sin but is this really the easiest way to code? Then I might just aswell keep the ginput() and start the maths....

slowlearner 2021-1-5