Fitting An Ellipse To A Set Of 2-D Points

I'm trying to fit an ellipse to a set of points described by x and y coordinates. I found a detailed explanation of how to do it here http://nicky.vanforeest.com/misc/fitEllipse/f

Solution 1:

Your code is absolutely fine, it is the patch definition that makes the trouble here. a and b of Ellipse are the full width. So you have to multiply the result of your fit by 2. Moreover the angle is in degree so you have to multiply by 180/np.pi. Finally, the zero is not at the same position, so you have to add 90.

Long story short change

Ellipse(center, a, b, phi)

to

ell = Ellipse(center, 2 * a, 2 * b,  phi * 180 / np.pi + 90 ) 

and you are good.