Adaptive window Fourier phase extraction method in optical three-dimensional measurement

Abstract

An adaptive window Fourier phase extraction method in optical three-dimensional measurement, which can be used to process a gray scale sine grating fringe diagram, is characterized by: (1) Carrying out empirical mode decomposition on a row of fringe signals so as to obtain a series of intrinsic mode functions; (2) Calculating an instantaneous frequency and a marginal spectrum of each intrinsic mode function, selecting the instantaneous frequency which can accurately describe a fringe signal change through analyzing the marginal spectrum; (3) Determining a background component of the fringe signal; (4) Using the determined instantaneous frequency to adaptively position a local stationary area and accordingly calculating a scale factor of a Gaussian window; (5) After removing the background component from an original signal, carrying out adaptive window Fourier transform so as to obtain a wrapped phase distribution. A global wrapped phase can be obtained after carrying out the above steps line-by-line. After expansion, an absolute phase can be obtained and can be converted into height information so that the three-dimensional measurement of an object can be realized. The method of the invention has strong adaptability. By using the method of the invention, measurement precision of measuring the object with a complex surface shape or containing an abrupt edge can be increased.

Description

technical field [0001] The invention belongs to the field of three-dimensional information reconstruction. Based on the gray-scale sinusoidal grating projection, the Hilbert-Huang transform method is used to analyze the deformed fringe image and obtain the instantaneous frequency and background component of the fringe, and use the obtained instantaneous frequency to adaptively calculate the window scale factor of the window Fourier transform, By directly performing Fourier transform or adaptive window Fourier transform on the fringe signal with the background removed to obtain accurate wrapping phase, this method is conducive to improving the measurement accuracy of objects with complex shapes or objects with steep edges. Background technique [0002] Optical three-dimensional measurement technology can accurately obtain three-dimensional surface data of objects, which can be used for three-dimensional model reconstruction, object surface profile measurement, detection of si...

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Problems solved by technology

[0005] Technical problem: Aiming at the problems such as the accuracy and adaptability of the window Fourier transform to obtain the wrapping phase of the fringe image in optical three-dimensional measurement, the present invention provides a solution in terms of adaptively performing the window Fourier transform and improving the solution accuracy of the wrapping phase. There is a solution

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