Abstract: The fitting problem of concentric elliptical arcs exists in astronomy image processing，computer vision and CAD.To solve the problem，the least-square orthogonal distance method of single ellipse’s fitting is extended，and its algorithm is proposed.The steps and pseudocodes of its implementation are also presented.The extended method unifies several ones which are for single circle fitting，single ellipse fitting and multiple concentric circles or ellipses fitting.All these fitting cases can be handled by one procedure.Experimental results show that the extended method is more accurate and stable than single arc fitting one.

Key words: ellipse fitting, multiple arcs fitting, geometric fitting, nonlinear least squares

摘要： 同心椭圆弧的拟合问题存在于计算机视觉、天文图像处理、CAD等领域。将椭圆的正交几何距离拟合算法推广到多个同心椭圆弧拟合上，提出一种同心椭圆弧拟合的处理方法。文中还给出了该方法实现的具体步骤和伪代码，该方法将单一圆、椭圆的拟合以及多个同心圆和椭圆的拟合统一了起来。实验表明该方法稳定、有效。

关键词: 椭圆拟合, 多弧拟合, 几何拟合, 非线性最小二乘