Research On 3D Reconstruction Of Low Texture Objects Based On Multi-color Structure Light And Light Field Information

Because of the advantages of high speed and high precision in 3D surface reconstruction of object,structured light illumination imaging technology has become a hot in surface reconstruction research and application,especially for low texture targets.However,when the surface fluctuation of the measurement scene is large,the reflected light is strong,or the object is blocked,the structured light measurement technology will lead to incomplete 3D point cloud data on the object surface,and the light field imaging technology can make up for this defect.The combination of optical field imaging technology is expected to obtain more information from the 4D optical field data of the surface in measured scene,provide additional geometric constraints,and greatly reduce the number of projected patterns,which is a very promising method.In this thesis,combining the two technical advantages,the optical field imaging is applied to the traditional fringe structured light technology,and the gray fringe image is replaced by the composite color fringe image for projection,and the projected pattern is compressed into one frame,which improves the image information carrying capacity and the object measurement efficiency.Firstly,based on the three-step phase shift technique,the three frames of phase shift fringes are encoded in the R,G,and B channels,and the color composite fringe pattern is projected onto the surface of the scene under test by using a projector.The optical field data is obtained by simulating a one-dimensional camera array with a single camera,and then the slope of the line fitting with equal phase values of each phase point is solved by using the polar plane method.Finally,the depth information of the scene is restored according to the mapping relationship between slope and depth,so as to carry out 3D reconstruction.In order to solve the problem of sinusoidal difference of fringe patterns caused by nonlinearity of system devices,this thesis introduces the transfer function method of black and white fringe into the correction of color composite fringe,and uses the concept of transfer function to correct color projection fringe.In addition,crosstalk of color channel exists in the acquired morphed fringe image.Based on the crosstalk model,calculating the matrix of crosstalk and compensating each colorfull channel fringe.Finally,the experimental system was designed and set up.Through the analysis of nonlinear correction of the system and crosstalk compensation of color channels,the accuracy changes after object reconstruction were observed,and the reconstruction quality of the three-dimensional reconstruction system in this paper was further improved.