A Polynomial Approximation Algorithm for Calculating Offsets of Ellipse Curves

An algorithm to approximate offsets of ellipse curves by piecewise cubic Bézier segments is proposed.After some necessary partition,the offset curve of each elliptic arc is approximated by a cubic Bézier segment.And the n the whole offset curve with G¹ is obtained.On one hand,the algorithm is simple to calculate because the control points of the Bézier segment can be expressed explicitly.On the othe r hand,the global error estimation for the algorithm is given.The error estimation can be used to determine the number of the segments in the partition of the ellipse.