Restoring circle using scattered points

Hello, all. I'm wonder if MatLab has tools to restore circle from 3D scattered points:

• center
• radius
• normal vector.

Screen shot can be seen from here: https://en.wikipedia.org/wiki/File:Least_square_conic.png

Second question: some points might be too far from scattered points. Is it possible to filter those out using MatLab?

Thank you

[Alessandro Masullo]

You can have a look at the Curve Fitting Toolbox

Answer 1

[Image Analyst]

See the FAQ:

http://matlab.wikia.com/wiki/FAQ#How_can_I_fit_a_circle_to_a_set_of_XY_data.3F

http://matlab.wikia.com/wiki/FAQ#How_can_I_fit_an_ellipse_or_other_shape_to_a_set_of_XY_data.3F

[Gennady]

it is in the 2d form: x^2+y^2+a(1)*x+a(2)*y+a(3)=0

What about 3d?

[Image Analyst]

I'd just average all the x,y,z coordinates to get the centroid, then calculate the average radius of all the points from that centroid. Maybe there's a better way - I don't know.

[Gennady]

This way i can get center point and radius, is it a way to get normal vector direction?