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

An adaptive window, three-dimensional measurement technology, applied in measurement devices, optical devices, special data processing applications, etc., to reduce the interference of zero-frequency spectrum and improve measurement accuracy

Inactive Publication Date: 2012-08-08
SOUTHEAST UNIV
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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

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

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[0075] The specific embodiments of the present invention will be further described below in conjunction with the drawings. In Windows operating system, VC++6.0 is selected as the programming tool to process the deformed fringe image collected by CCD. This example uses plastic foam as the measured object, and finally obtains a more accurate full-field package phase distribution sum containing three-dimensional information.

[0076] figure 1 It is a flowchart of the entire process of the present invention.

[0077] In optical three-dimensional measurement, when the fringe pattern is extracted for the wrapped phase, the current time-frequency analysis method has low measurement accuracy for objects with complex surfaces or steep edges. The present invention proposes a method based on Hilbert-Huang transform. Scale window Fourier phase extraction method. First, the empirical mode decomposition method is used to decompose the acquired deformed fringe image line by line and carry out ...

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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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Application Information

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IPC IPC(8): G01B11/25
CPCG01B11/25G06F17/00G06T7/00
Inventor 达飞鹏王辰星
Owner SOUTHEAST UNIV
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