Finding Center of Arc and Forming Circle from an Image

hi, I have a zoomed in image the Moon and from it I need to estimate the Moon Center and form its full outline.

The original image is this one:

Using various commands such as bwareaopen, imcomplement, I have managed to isolate its outline and laid it out on an all black canvass:

Then from here I want to find the center of the circle (moon) and extrapolate its outline: e.g draw a circle of the full moon in the image.

I have tried the imfindcircles command but it seems having a hard time to detect the outline.

Any help with this will be greatly appreciated!

Thank you!

Answer 1

[Eleanor Betton]

https://blogs.mathworks.com/pick/2008/03/14/fitting-a-circle-easily/

This give a good walk though on fitting a circle using circfit. It might be worth trying this. Once you have the circle you can calculate the centre.

[Edgar Paolo Violan]

Circfit worked perfectly! It needed aditional work to plot the boundary of the arc, but the example greatly helped

Thank you!