Non-linear self-correction structured light three-dimensional measurement method and system for sine fringes

A sinusoidal fringe and three-dimensional measurement technology, which is applied in the direction of measuring devices, optical devices, instruments, etc., can solve the problems of large measurement time consumption and difficult realization of three-dimensional measurement, so as to improve the phase accuracy of wrapping, improve the accuracy of unwrapping, and ensure accurate sexual effect

Active Publication Date: 2021-07-02
GUANGDONG UNIV OF TECH
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Problems solved by technology

However, a large number of projections will undoubtedly consume a large amount of measurement time, making it difficult to achieve high-speed and high-precision 3D measurement

Method used

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  • Non-linear self-correction structured light three-dimensional measurement method and system for sine fringes
  • Non-linear self-correction structured light three-dimensional measurement method and system for sine fringes
  • Non-linear self-correction structured light three-dimensional measurement method and system for sine fringes

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Embodiment Construction

[0048] First, the present invention obtains the mathematical model of the DC component of the actual stripes by deriving the following formula.

[0049] In the measurement, since the light intensity actually obtained by the camera can be expressed by the polynomial form of the ideal light intensity of the projector, the projected fringe image is: in is the phase, A is the mean strength, B is the modulation strength, and n is the serial number of the amplitude.

[0050] Further, since the error source of the three-step phase shift method mainly comes from the second harmonic, this method assumes that the light intensity response of the system is a second-order polynomial: I n '=f(I n )≈a 0 +a 1 I n +a 2 I n 2 . After the system response, the expression of the actual light intensity is calculated as:

[0051]

[0052] which is: where a 0 , a 1 , a 2 is the system parameter of the nonlinear response of the system.

[0053] The DC component of the actual fringe ...

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Abstract

The invention discloses a non-linear self-correction structured light three-dimensional measurement method and system for sine fringes, and relates to the technical field of optical three-dimensional measurement. A new mathematical model of a direct-current component is provided according to system nonlinear response, respective modulation intensity and mean value intensity of three groups of sine fringes are adjusted based on the model of the direct-current component, an equation about nonlinear response is established, respective nonlinear corresponding parameters of each pixel are obtained through calculation, the gray level of the fringe image is corrected through the inverse function of the nonlinear response equation, the wrapping phase and the unwrapping phase of the corrected fringe image are calculated, finally, a three-dimensional point cloud is reconstructed according to triangulation ranging, a three-dimensional model of the object to be measured is built, and three-dimensional measurement of the object to be measured is completed. Projection time and huge matrix inversion calculation time consumption do not need to be increased, nonlinear errors of different frequency phases are reduced, therefore, the phase wrapping precision and the unwrapping precision can be improved at the same time, and high-speed and high-precision three-dimensional measurement is achieved.

Description

technical field [0001] The invention relates to the technical field of optical three-dimensional measurement, in particular to a nonlinear self-correcting structured light three-dimensional measurement method and system for sinusoidal fringes. Background technique [0002] Three-dimensional measurement has always been the focus of development in the field of measurement. With the development of data processing capabilities, the popularity of 3D data is also increasing. Three-dimensional measurement is widely used in reverse engineering, cultural relics measurement, and industrial inspection. Based on the rapid development of projection and imaging technology, the structured light measurement method has the characteristics of high speed, high precision and wide application range, and is one of the widely used non-contact 3D measurement methods. Phase-shift profilometry is the most representative method among structured light methods. Through phase modulation and decoding, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/25
CPCG01B11/254
Inventor 高健郑卓鋆张揽宇莫健华陈云张凯张昱贺云波陈新
Owner GUANGDONG UNIV OF TECH
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