归一化等相面的在线三维测量像素匹配方法

Pixel matching method in on-line three-dimensional measurement based on normalized equiphase plane

像素匹配是在线三维测量中的关键技术之一,提出了基于归一化等相面的在线三维测量像素匹配方法。仅投一帧正弦光栅条纹到在线运动的物体上,由CCD再依次移动相同步距时刻同步采集受物体调制的变形条纹图。利用FTP方法预测物体不同位置的相位信息并进行归一化,再以二值化等相面协助像素匹配,不仅实现了物体在各帧条纹图中的像素坐标一一对应,而且归一化减少了由于物体运动产生的不同位置相位展开起始点不一致导致的不同位置相位展开的差异性而引入的误差,同时节省了像素匹配计算量。对最大高度为8 mm的peaks函数型物体的模拟结果表明:均方差为0.021 mm,像素匹配时间上,该方法较直接用FTP方法预测得到的相位为模板进行像素匹配缩短了近2倍,同是实物测量也验证了该方法的有效性和可行性。所提方法不仅可以保证在线三维测量的精度,而且有效地提高了测量速度。

A pixel matching method in on-line three-dimensional measurement based on normalized equiphase plane was proposed. Only one fixed sinusoidal fringe was needed to project on a measured object moving on the pipeline. While the object was coming to some positions with a certain adjacent displacement, the deformed patterns modulated by the object were captured synchronously by the CCD camera. Dealing the captured deformed patterns with PTP method, the phase information of the object in those positions could be predicted and normalized, and the normalized equiphase plane was transformed into integer as the mask to assist the pixel matching, which not only realized the one-to-one corresponding of the object, but normalization reduced the error introduced by these differences of the object＇s unwrapped phase in different positions caused by the object＇s movement, further binarization of the phase feature improved the pixel matching＇s speed as well. The simulation result of the ＂peaks＂ function object with the max height 8 mm showed the RMS was 0.021 ram. Meanwhile, as for timespent of the pixel matching, the average time spent with the proposed method was about 2 multiples faster than the method based on phase prediction. The object measurement also showed its feasibility and validity of the proposed method. The proposed method could not only guarantee the accuracy of the online 3D measurement, but improve the measurement speed apparently.