Research On 3D Measurement Method Of Dual Frequency Fringe Projection

Optical 3D measurement technology is a measurement technology that relies on machine vision and is cross-integrated with optoelectronics,computer science and other disciplines.It has the advantages of non-contact,high measurement accuracy,strong robustness,good real-time performance and rich information.With the rapid development of computer performance and image processing algorithms,its measurement accuracy is constantly improving,and its measurement cost is also decreasing,so it is widely used in industrial production,mechanical engineering,biomedicine etc.In optical 3D measurement technology,fringe projection profilometry is one of the most common methods.This paper mainly studies the 3D measurement system based on dual-frequency fringe projection,and have optimized the robustness and measurement efficiency of this system.The detailed research contents are as follows:(1)Improved the spatial-shifting two-wavelength algorithm(SSTW).Aiming at the limitation of wavelength selection in SSTW algorithm,a look-up table based spatial phaseshifting two-wavelength algorithm(LUT-SSTW)is proposed to expand the range of wavelength selection.(2)Improved the LUT-SSTW algorithm.In the process of using structured light 3D measurement,due to discrete sampling,random noise and nonlinear response of fringe projection profilometry,the induced phase error may be reflected in the wrapped phase,thus affecting the robustness of the LUT-SSTW algorithm.According to the corresponding error analysis and adaptability,geometric constraints are added to the LUT-SSTW algorithm to enhance its robustness.(3)Reduced the number of fringe projections of the LUT-SSTW algorithm based on geometric constraints to improve the efficiency of 3D reconstruction.The number of fringe patterns projected by the LUT-SSTW algorithm based on geometric constraints has been studied,the dual-frequency three-step phase shift has been changed to a dual-frequency composite fringe with five-step phase shift to solve the wrapping phase,and the six fringe patterns are reduced to five fringe patterns,which improves the measurement effectiveness.(4)Developed dual-frequency fringe projection 3D measurement system software.The projector and camera control software in the structured light 3D reconstruction system are integrated into one interface,which is convenient to improve the efficiency of 3D reconstruction.In this paper,the feasibility,correctness and robustness of the proposed improved algorithm have been verified by simulation and real experiments.At the same time,the experimental measurement of the blade area proves that the algorithm has better robustness,higher accuracy and higher efficiency.