re sphere from points there is another useful method based on least sqyares estimation of the sphere equation parameters the points x y z on a spherical surface with radius r and center a b c can be written as x a y b z c r this equation can be rewritten into the following form ax by cz r a b c x y z approximate the left hand part by f x y z p x p x p z p for all datapoints i c determine the parameters p p which minimise the average error f x y z x y z in numerical recipes in c can be found algorithms to solve these parameters the best fitting sphere will have center a b c p p p radius r sqrt p a a b b c c so at last will this solve you sphere estination problem at least for the most situations i think quick van rijt rytg fel tno nl
