• 计算机视觉与虚拟现实 •

### 基于莱特准则的椭圆拟合优化算法

1. 上海大学 机电工程与自动化学院, 上海 200072
• 收稿日期:2016-06-12 修回日期:2016-09-05 出版日期:2017-01-10 发布日期:2017-01-09
• 通讯作者: 曹俊丽
• 作者简介:曹俊丽(1991-),女,内蒙古乌兰察布人,硕士研究生,主要研究方向:计算机图像处理、控制系统设计;李居峰(1956-),男,上海人,副教授,硕士,主要研究方向:机电一体化、控制系统设计。

### Improved ellipse fitting algorithm based on Letts criterion

1. School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200072, China
• Received:2016-06-12 Revised:2016-09-05 Online:2017-01-10 Published:2017-01-09

Abstract: The commonly used Least Square (LS) ellipse fitting algorithm based on minimum algebraic distance is simple and easy to implement, but it has no choice to the sample points, which leads to the fitting results are easily inaccurate due to the error points. According to this case, an improved ellipse fitting algorithm based on Letts criterion was proposed to overcome the shortage of LS algorithm. Firstly, the ellipse was fitted from the fitting curve by using the LS ellipse fitting algorithm based on minimum algebraic distance. Then, the algebraic distance of ellipse fitted by LS algorithm from the point distance on the fitting curve was set as the fitting point set. After the point set was verified to be normal distribution, the points which were greater than|3σ|were determined to be outliers and eliminated by using Letts criterion. Then the steps above were repeated until all points were within the scope of [-3σ,]. Finally, the best fitting ellipse was obtained. The simulation experiment results show that the fitting error of the improved algorithm based on Letts criterion is within 1.0%, and its fitting accuracy is improved by at least 2 percentage points compared with the LS algorithm under the same condition. The simulation result and the practical application in roundness measurement of cigarette verify the effectiveness of the improved algorithm.