一种面向对缝测量的双线结构光光条中心提取方法

针对双线结构光对缝测量系统中光条中心的提取问题,提出一种基于自适应阈值和傅里叶拟合的光条中心亚像素提取方法。该方法根据双线结构光光带截面灰度呈近似周期性分布的特点,先采用骨架细化法获得条纹中心初始位置,再通过均方灰度梯度求取骨架上每一点的法线方向,然后采用自适应阈值法提取出条纹各列法向宽度值,最后利用条纹法向宽度内的灰度值数据进行傅里叶拟合,求取拟合曲线的峰值,连接峰值点得到光条的中心线。试验结果表明,该方法提取的光条中心点到中心点拟合直线的平均距离为0.1182个像素和0.1428个像素,优于骨架细化法和高斯拟合法,并且该方法能够一次完成两根结构光光条中心的精确提取,对缝的测量精度能够达到0.04mm。

Extracting the Centers of Dual Linear Structured Light Stripes for Seam Measurement

Aiming at extracting the center position of light stripe in dual structured light seam measurement system,a new method of sub-pixel center line abstraction from light strip based on adaptive threshold and Fourier fitting has been proposed.According to the gray scale of optical cross section subjects to periodic distribution,in the first step,the proposed approach gets the initial position of strip center by skeleton thinning approach.Then,the normal direction of each point on skeleton lines is obtained by using the mean square of gray scale gradient.It uses adaptive threshold method to get the normal width of each structured light strip.Finally,by doing Fourier fitting job using the gray scale within the normal width,the peak value of the fitting curve could be obtained,and the center line as well.The experimental results show that the average distance between the extracting corners and the line fitted by the extracting centers is only 0.1182 pixels and 0.1428 pixels,which is better than the skeleton thinning method and Gauss fitting method,meanwhile the method can improve the accuracy of center line extraction from strip-structured light,the seam measurement precision can reach 0.04mm.