Domain mapping simple gamma calculation method for fringe projection contour measurement

Abstract

The invention provides a domain mapping simple gamma calculation method for fringe projection profile measurement, wherein the method comprises the following steps: step 1, generating a series of three-step phase shift fringe patterns for coding different gamma values through a computer, and calculating wrapped phases through a phase shift method; step 2, mapping the wrapped phase values to a unit circle; step 3, solving a nearest neighbor index; step 4, performing fitting by using a Gaussian function; and step 5, describing a Gaussian curve by using a Gaussian parameter combination value. According to the algorithm, the wrapped phases are mapped to the unit circle. By analyzing a wrapped phase diagram with a gamma interval of 0.001, it can be seen that nonlinear distribution of the wrapped phases is regular, the nonlinear distribution can be converted into nearest neighbor exponential distribution of the unit circle, and small gamma differences can be distinguished.

Description

technical field [0001] The invention relates to the technical field of structural optics three-dimensional measurement, in particular to a domain mapping simple gamma calculation method for fringe projection profile measurement. Background technique [0002] Fringe projection profilometer is a typical non-contact 3D optical surface measurement method, which plays an important role in many fields such as industrial manufacturing, entertainment and medical treatment; usually, a phase shift algorithm is used to obtain an accurate absolute phase map containing depth information of the object , however, the intensity response of digital projectors and cameras is non-linear in order to obtain a better visual experience, the non-linear response of the equivalent gamma transformation is usually called the gamma effect, due to the gamma effect, the captured fringe pattern has a non-linear Linear distortion, which causes periodic phase errors and corrugated surfaces on 3D point clouds...

AI Technical Summary

Problems solved by technology

Gamma and phase are calculated simultaneously, and Zhang et al. proposed an algorithm to obtain gamma by fitting the measured response curve, which is generated by projecting a series of images of different intensities. In addition, some gamma calculation algorithms A general precision distortion model was constructed to reduce the number of extra fringe images. During projection, if the projected fringe pattern couples nonlinearity and ambient light noise together, the solution may be more complicated. Yu et al. will wrap the phase The characteristics of the probability distribution function and the gamma of each system are linked, and the gamma is detected from the simulated package phase by solving the correlation of the corresponding curves, regardless of the complex model analysis of the fringe pattern

[0004] However, this approach uses a one-to-one calculation of gamma and wrap phase maps, requiring generation of more wrap curves to match tiny gamma values

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