How to plot a circle on top of my plotted image
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I have an image plotted and I wanted to plot a circle on top of it with the same centroid of the image.
I want the radius to be 500 and I want it done with a red color, of somebody could help me with this.
thank you very much
回答（4 个）
lvn
2014-5-9
See this answer http://www.mathworks.com/matlabcentral/answers/98665-how-do-i-plot-a-circle-with-a-given-radius-and-center
To plot on top of an existing figure, start with
hold on
Ruben Alfaro
2014-5-9
0 个投票
1 个评论
Roberto
2014-5-9
post the error you're having, or explain why it doesn't work for you?
Image Analyst
2014-5-9
Try this:
grayImage = imread('concordorthophoto.png');
imshow(grayImage);
axis on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
[rows, columns, numberOfColorChannels] = size(grayImage);
hold on; % Don't let plot blow away the image.
xCenter = columns / 2;
yCenter = rows / 2;
theta = 0 : 0.01 : 2*pi;
radius = 500;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
plot(x, y, 'r-', 'LineWidth', 3);
grid on;
Hugo Diaz
2022-2-5
0 个投票
%The trick is to do it 3D, and a 2D plot is like a view from above.
% your 2D plot. If your function f(x,y) < m, then
hold on
r = 1;
teta = -pi:0.01:pi;
x = r * cos(teta);
y = r * sin(teta);
plot3(x, y, m * ones(1, numel(x)), 'Color','k')
hold off
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2014-5-9
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