动态模板与互相关在激光三角测量中的应用

Application of Dynamic Template and Cross Correlation in Laser Triangulation

针对在激光三角法测量中,像点光强分布不规则变化导致质心法测量精度下降的问题,提出基于动态模板的归一化互相关函数法(N C C)计算像点位移。该方法将线阵C C D当前帧采集的像点图像作为下一帧图像的匹配模板,利用NCC法计算前后两帧像点的相对位移。以金属表面作为被测表面进行了实测,实验结果表明,动态模板的NCC法对像点光强变化具有较高的鲁棒性,测量精度为1%,绝对误差不大于6μm。该方法相对于传统质心法在测量强反射表面位移时具有较大优势,对拓宽三角测量的适用范围有一定帮助。

In order to solve the problem that the irregular changes of light intensity distribution of image point in laser triangulation, which causes measurement accuracy with Centroid method declines, the normalized cross colwelation（NCC） method based on dynamic template is proposed to calculate the image point displacement. In this method, the current frame of the image point collected by the linear CCD is used as the matching template for the next frame, and the relative displacement of these two image points can be calculated by the NCC method. A metal gauge block is used as the measured surface for the experiment, and the result shows that the method is of stronger robustness on light intensity distribution changes than Centroid method. The measurement accuracy is 1% and the absolute error is no more than 6 μm. Compared with the traditional method, this method has a great advantage in measuring the displacement of the strong reflective surface, which helps to broaden the application scope of laser triangulation.