How to draw circle with imellipse?

Hi

I want to draw a circle with imellipse. I used something like:

AA = imellipse(gca,[xmin ymin radius radius]);

but I can only specify the xmin and ymin of the circle, while I want to specify the center.

How can I do so?

Thanks!

Steven

Answer 1

[Image Analyst]

This is well explained by the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_an_ellipse.3F

[Image Analyst]

If you really want to do it with imellipse, you can just compute the xmin and ymin from the diameter. By the way, imellipse takes width and height (diameter) not radius.

diameter = 10;
radius = diameter / 2;
xCenter = 60;
yCenter = 30;
xMin= xCenter - radius;
yMin = yCenter - radius;
hEllipse = imellipse(gca,[xMin, yMin, diameter, diameter]);
% Plot center
hold on;
plot(xCenter, yCenter, 'r+', 'LineWidth', 5, 'MarkerSize', 20);
grid on;

[Steven]

Thanks

Answer 2

[Tim Jackman]

In R2018b you can create a circular ROI with the drawcircle function.

[Image Analyst]

Very nice new function (finally!).

[Matt J]

Unfortunately, drawcircle doesn't seem to come with a wait method letting you finalize the position of the circle, nor either features of the imroi classes like positionConstraintFcns.

[Image Analyst]

It does have a 'DrawingArea' option to restrict the drawing area to what you specify.

Have you tried waitfor()?