结合分层处理的激光光条亚像素中心提取方法

为实现大型航空零件三维测量过程中激光光条的快速高精度提取，提出了一种结合分层处理的激光光条亚像素中心提取方法。首先，根据序列图像的结构不变性将高分辨率图像压缩为低分辨图像。接着，通过二次拟合求解低分辨率图像中激光光条中心的法线斜率。然后，将低分辨图像求得的法线斜率还原到高分辨激光光条图像中。进而通过灰度重心判断准则，快速计算激光光条的亚像素中心。最后，采用所提出的方法分别在实验室和大型航空零件装配测试台上进行了复合材料标准样件和复杂零件的三维形貌测量。实验结果表明:该方法的单激光光条重建误差为0.269 mm，三维形面的重建误差为0.268 mm。该方法可有效提高工程零件快速测量过程中激光光条提取精度，满足大型航空零件现场测量的工程要求。

Sub-pixel center extraction method of laser stripe center based on hierarchical processing

A sub-pixel center extraction algorithm based on hierarchical processing was proposed for the implementation of laser stripe processing in the large aerospace parts measurement with high speed and precision. Firstly, the high-resolution image was compressed into low-resolution image with structural invariance. Then, the normal vector of the center of laser stripe was calculated by using quadratic curve fitting in the low-resolution image. The normal vector in the low-resolution image was reproduced to the high-resolution image based on the theory of normal regression. The judgment of gray center on normal direction was established to determine calculated pixels. The sub-pixel center of calculated pixels on the normal direction was accurately calculated by the gray weighted centroid method. Finally, the presented method was utilized to measure a composite material standard part and complex aviation parts in the laboratory and assembly testing machine, respectively. Experimental results show that the precision of the reconstruction of a single stripe on the surface of object is 0.269 mm and the precision of three-dimension surface measurement is 0.268 mm. It indicates that the proposed method can improve the speed and precision of the engineering measurement of large part. Moreover, the method can satisfy the requirements of the in-site measurement of large aerial parts.