How to retrieve the centroid and angle of an ellipse drawn on an image in a gui?

I want to create an interactive ellipse on an image in a gui and retrieve its poperties like semi-major axis,semi-minor axis, angle and centroid for the same. I am struck at this. Using imellipse, I am not able to get the centroid and the angle. I have to get these values in a structure and then generate a xml file of it. Thanks!

Answer 1

[Matt J]

If you have a well-distributed set of points on the ellipse, you can use the attached file to fit the points. The output gives all the ellipse parameters that you mentioned.

[Nisha Bharti]

It's giving this error:

Attempted to access XY(2,:); index out of bounds because numel(XY)=1.

Error in ellipsefit (line 6) Y=XY(2,:).' - cxy(2);

[Matt J]

The error means that you have called ellipsefit(XY) with a scalar value for XY. The expectation is that XY is a 2xN matrix whose columns are N points on the ellipse.

Answer 2

[Image Analyst]

See my attached demo which will draw ellipses at various angles.