  As the spherical object can be seen everywhere, we should extract the ellipse
image accurately and fit it by implicit algebraic curve in order to finish the
3D reconstruction. In this paper, we propose a new ellipse fitting algorithm
which only needs three points to fit the projection of spherical object and is
different from the traditional algorithms that need at least five point. The
fitting procedure is just similar as the estimation of Fundamental Matrix
estimation by seven points, and the RANSAC algorithm has also been used to
exclude the interference of noise and scattered points.
