Does anyone know how can finding angle in an ellipse

 The left ellipse is an fitted ellipse to an object in time (t) and right one is in t+1. I mean after 1 minute the object (fitted ellipse) was rotated about alpha degree. how can I find (α) in the rotated ellipse (right one)?

[Image Analyst]

In what form is your data? A list of perimeter (x,y) coordinates? An image? Do you have the Image Processing Toolbox?

[Abo]

the left ellipse is an fitted ellipse to an object in time (t) and right one is in t+1. I mean after 1 minute the ellipse was rotated about alpha degree.

[Image Analyst]

That doesn't answer my question. What kind of data are you starting with. If you use the "whos" function on your variables, what does it say? Is it a rows-by-column 2 or 3 D array (an image), or is it a N-by-2 array (a list of x,y coordinates)? Please read this http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Abo]

sorry Image Analyst, I've used this method: http://blogs.mathworks.com/steve/2010/07/30/visualizing-regionprops-ellipse-measurements/ for ellipse fitting and I have a list of x,y coordinates for (2D image).

Answer 1

[Guillaume]

Since you're using regionprops to fit your ellipses, and one of the properties returned by regionprop is the ellipse orientation, why can't you just subtract the angles of your two ellipses?

[Image Analyst]

Exactly what I was going to suggest (now that he clarified what he was doing).