Research On Three-dimensional Measurement Technology Based On Binary Defocusing Structured Light

With the development of science and technology and the advancement of society,the application of three-dimensional topography measurement in industry and life is becoming more and more widespread.Digital fringe projection technology has wide application prospects in the fields of industrial detection,virtual reality and biomedicine due to its advantages of non-contact,fast and high precision,and has become a research focus of 3D measurement technology.But the digital fringe projection technology still has corresponding problems.This thesis focuses on the non-linear problems caused by the gamma effect of commercial projectors in digital fringe projection technology.This thesis first introduced the principle of the three-dimensional measurement technology of binary defocused structured light,then studied the asymmetry of the Sierra Lite dithering algorithm,and proposed an "S" vertical scanning Sierra Lite dithering algorithm to improve it,and then two optimization algorithms were proposed based on the spatial and frequency domains respectively.The genetic algorithm was used to optimize the binary pattern.Finally,the three optimization methods proposed in this paper were compared.The main content of this article includes four aspects(1)The thesis described the principle of the three-dimensional measurement technology of binary defocusing structured light,analyzed the filter model of the defocusing projection system and the existing methods of generating binary structured light patterns,and studied the influence of its frequency domain characteristics on the defocusing effect.(2)The thesis studied the effect of the asymmetry of the Sierra Lite dithering algorithm on the phase error of structured light under different defocusing amounts,different fringe periods,and different phase shift steps and found that the phase error of using the vertical scanning dithering algorithm is relatively small.Then the thesis proposed a Sierra Lite dithering algorithm for "S" vertical scanning.This method improves the symmetry of the longitudinal stripes to a certain extent.It was verified by experiments that the method can effectively improve the accuracy of 3D measurement,especially when the stripes are narrow(3)This thesis proposed a method for generating a fringe-optimized fringe based on the spatial domain.By minimizing the gray-scale error between the binary defocusing pattern and the ideal sinusoidal pattern,and using genetic algorithms to optimize the binary fringe,and using the binary block optimization technology to speed up the optimization process.(4)This thesis proposed a method for generating fringe optimized fringe based on frequency domain.The objective is to minimize the spectral error between the optimized pattern and the ideal sinusoidal pattern by using genetic algorithm to optimize the binary defocus pattern.This method can significantly improve the fringe quality of the dithering algorithm,and it is robust to different projector defocus levels.