小波变换轮廓术中快速相位展开方法研究

Novel phase unwrapping method for wavelet profilometry

针对小波变换轮廓术中相位展开的精确性和快速性问题,提出了一种新的适用于小波变换轮廓术的相位展开方法。在使用小波变换得到条纹图像的相对相位分布的基础上,详细分析了利用小波变换脊处的尺度因子建立质量图指导相位展开的理论依据和实现方法,这种质量图建立方法有效反映了条纹图像各点的可靠性。在相位展开方面,针对全局洪水相位展开算法计算时间较长的问题,提出了根据质量图将相对相位分布图分层,然后逐层采用不同算法展开的方法。与全场洪水相位展开算法相比,该方法在保持较高测量精度的同时极大减少了相位展开所需的运算时间。计算机仿真和实物测量实验说明使用该方法可以得到准确的绝对相位值,处理速度较快。

A novel phase unwrapping method used in wavelet profilometry is presented to improve the accuracy and speed of the unwrapping process. We use wavelet transform to get the wrapped phase of the fringe image. The theory and implementation of building quality map using scale factor at wavelet ridge is discussed in detail. The presented method can reflect the reliability of the pixel in fringe image effectively. In the phase unwrapping process, aiming at the long calculation time problem of flood fill phase unwrapping algorithm, we divide the wrapped phase map into two levels following the established quality map and unwrap the two levels using different algorithms. Compared with the flood fill algorithm, using the proposed method we can get accurate result while the calculation time of the phase un- wrapping process is much less. Computer simulation and experiment result verify that the 3D information of an object can be obtained rapidly and accurately using the proposed method.