Getting points with ginput from image and plotting simultaneously each selected point

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Alfonso 2018-6-3

0
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https://ww2.mathworks.cn/matlabcentral/answers/403814-getting-points-with-ginput-from-image-and-plotting-simultaneously-each-selected-point

评论： Walter Roberson 2020-7-1

I am trying to select an unlimited number of points from an image ([x,y] = ginput), and each time I select a point I want to plot it, so I can have a real time reference of each point I get.

I have tried with this code, but I don't get it to work.

Here is the code I use:

I = imread('cameraman.tif'); % example
imshow(I);
axis on;
button = 1;
i = 1;
n = 1;
while button(i) == 1
   [x,y, button] = ginput(1)
   x_n(n) = x(i); % save all points you continue getting
   x_n(n) = y(i);
   hold on
   plot(x(i),y(i),'r')
   drawnow
   n=n+1;
end

I have read some answers where they use for loops with a limited number of points to be selected, but I must have an unlimited number of points, that's why I use as loop condition the pressed button.

Thank you for any help in advance.

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Walter Roberson 2018-6-3

When the user finally clicks a button other than 1, do you want to plot the final point, or do you want to consider that to immediately terminate without entering the point the user is at?

Alfonso 2018-6-3

Each time the user clicks the button with value 1 it means the user selected a new point, so it must plot the point before the user continues selecting more points.

When the user clicks a button different to 1, this means the user has finished, so the while loop breaks.

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采纳的回答

Walter Roberson 2018-6-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/403814-getting-points-with-ginput-from-image-and-plotting-simultaneously-each-selected-point#answer_323009

编辑：Walter Roberson 2019-11-16

在 MATLAB Online 中打开

n = 0;
while true
   [x, y, button] = ginput(1);
   if isempty(x) || button(1) == 1; break; end
   n = n+1;
   x_n(n) = x(1); % save all points you continue getting
   y_n(n) = y(1);
   hold on
   plot(x(1), y(1), 'r')
   drawnow
end