Phase nonlinear error compensation method in surface structured light three-dimensional imaging technology

Abstract

The invention discloses a phase nonlinear error compensation method in a surface structured light three-dimensional imaging technology. The method comprises the following steps that: a four-step phase shift algorithm is employed to obtain phase information, and the phase information is substituted into a ratio of second harmonic to first harmonic, and a higher harmonic component ratio containing a gamma value is obtained; a harmonic component is obtained according to discrete Fourier transform, the gamma value is generally between 0 and 3, the gamma value which is not equal to 1 is pre-coded into a fringe image, a modulated harmonic component is obtained, and the pre-modulated gamma value of each pixel in the fringe image projected by a projector is calculated; and the pre-modulated gamma value obtained by calculation and the reflectivity are loaded into a projection fringe algorithm of the projector, and a camera and projector gray value modeling and least square approximation technology are utilized to obtain the accurate gamma value of each pixel in the fringe image projected by the projector, and the original fringe image of the projector is corrected through the accurate gamma value. According to the method of the invention, the error of the image collected by a camera can be greatly reduced.

Description

technical field [0001] The invention relates to the field of surface structured light three-dimensional imaging technology, in particular to a phase nonlinear error compensation method in the surface structured light three-dimensional imaging technology. Background technique [0002] Surface structured light 3D imaging technology has the advantages of simple structure, high measurement accuracy and no need to touch the measured object. In recent years, it has been widely used in industrial online inspection, machine vision, biomedicine, geological exploration, computer-aided design and processing and other fields. In the grid projection technology, ideally, the fringe image collected by the camera is sinusoidal. Note that this is actually collected by the camera, not projected by the projector. Grating projection technology is an optical three-dimensional measurement technology. In order to simplify the measurement process, the simplest method is to directly project a set of...

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Problems solved by technology

[0005] 2), collect a large number of images, obtain the gamma correction value error table of the image, and the subsequent projection image is corrected by the look-up table method, which needs to obtain the error table again after replacing the measured object, which is inflexible;

[0006] 3) Through the neural network algorithm, the training model approximates the gamma correction value of the image, and then modulates the projected image. This method is essentially an optimization algorithm and has certain advantages, but in the process of approximating the value, parameter adjustment is required , as well as the need to collect a large number of pictures, it also lacks certain flexibility

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