next up previous
Next: About this document Up: Least-square fitting of circles Previous: Approximated Euclidean Distance

Algebraic Distance

The algebraic distance of a point to a circle is simply . Thus, we have a simple procedure to estimate the parameters: find the parameters that minimizes

Define the design matrix:

The least square solution is the eigenvector of the smallest eigenvalue of the matrix .

Some matlab code for the fit is here and for conversion to standard form is here.

Bob Fisher
Thu Aug 3 17:26:57 BST 2000