关键词: 双树复小波变换, 评定基准面, 频带能量法；三维粗糙表面

Abstract:

At present, wavelet transform applied to the establishment of three-dimensional rough surface datum was mainly the first and the second-generation wavelet. However, they had some defects such as the shift variation and poor directional selectivity and so on, especially the selection of optimum wavelet base and the determination of the times of wavelet decomposition, which was always the difficult points of surface evaluation. Now the third generation wavelet DT-CWT was used for valuation of three-dimensional rough surfaces, by comparing the datum errors and maximum reconstruction error of the actual reconstruction images of the three wavelets as well as simulation of three-dimensional rough surface, the optimality of DT-CWT was obtained. Band energy method was employed to ascertain the times of wavelet decomposition and then mean square error S which was the characterization parameter of three dimensional simulation surfaces was used to check the correctness of decomposition times. Finally, the reference surface of the three dimensional nonstationary random rough surface with fractal properties was extracted by DT-CWT transform. The results prove the effectiveness.

Key words: dual-tree complex wavelet transform(DT-CWT), evaluation datum, band energy method;three-dimensional rough surface