石英摆片视觉测量系统亚像素精度标定方法

Calibration Method with Sub-pixel Precision for Vision Measurement System of Quartz Pendulous Reed

在以图像测量技术为核心的石英摆片平面几何参数检测系统中,视觉测量系统标定精度是保证石英摆片平面几何参数高精度测量的前提。为此,引入Sobel算子和Zernike矩图像处理技术实现测量系统高精度标定。该方法利用预先设计的标准图片,对视觉测量系统进行标定。由Sobel算子对标准图片中的控制点进行单像素精度的初始位置定位,在此基础上,利用Zernike矩亚像素定位算法实现对控制点的精确定位。实验结果表明:该方法可以对行列方向同时进行标定,标定精度可达1/30像素以上。

For the measurement system of geometrical plane parameters based on image measuring technique to the quartz pendulous reed, the calibration precision of camera system is prerequisite. To improve the precision, a new calibration method, which combined Sobel operator and Zernike moments operator technique, was presented. In this method, a designed model picture was used to calibrating the camera system, Sobel operator was made use to calculate gray-level gradient image and located one pixel accuracy; on this basis, the sub-pixel positioning algorithm of Zernike moments operator was made use to calculate the accurate locations of control points. The experimental results show that the proposed algorithm can calibrate camera system synchronously along X and Y directions, and 1/30-pixel precision can be obtained during practical application.