Research Of Fast 3-dimensional Shape Measurement Based On Three-color Channel Fringe Defocused Projection

Structured light measurement technology based on fringe projection has the advantages of high precision,high speed and low cost,and has a wide application prospect.In recent years,the defocused binary fringe projection method has been proposed,resulting in great improvement of projection speed and measurement speed,bringing fast measurement and dynamic measurement to the front stage.In this thesis,a 3-D measure system was built to perform researches on 3-D reconstruction referencing the decosed fringe projection method.Key points including methods of enhancing the measuring speed of defocused technology and error compensation in motion measurement,are mainly explored.New model and algorithm are proposed.The main research work and innovation of this thesis are as follows:1.A measuring method based on defocused 3-channel binary fringe projection is proposed.The principle of DMD projection is explained,and the reason why the traditional 8bit color fringe projection cannot play the performance of DMD device is analyzed.In order to further improve the measurement speed when the projector speed levels up with the camera frame rat,this method encodes defocused binary phase-shifting fringes in three channels of DLP projector.Within one frame,the phase-shifting images encoded in three channels are projected and captured in sequence,and the digital images obtained are decomposed into three channels to recover the original fringe image.In the aspect of crosstalk decomposition,it is analyzed that the source of crosstalk is the frequency response overlap at the sensitive chip of the camera while a crosstalk-free DLP projector is adopted,and a method using monochrome camera to calibrate crosstalk matrix is proposed.The monochrome camera with the same sensitive chip as the color camera can introducing additional information,making assumptions on the surface reflectivity of the calibration object unnecessary.Experimental results show that the proposed three channel defocusing projection mode is faster than the previous defocusing projection mode and color fringe projection mode.In terms of accuracy,the nonlinear error of projector for color fringe projection is solved,and the crosstalk resolution accuracy is higher.It is also robust for color object measurement and dynamic measurement.2.A dynamic measurement modeling method based on motion quantity is proposed.The effects of phase-shifting image bit error caused by inter frame motion and imaging error caused by single frame time motion in dynamic measurement are analyzed.A new phase-shifting model with these two kinds of dynamic errors is proposed,and a numerical method and initial value calculation method are provided.The existence and scale of the error are verified by the simulation experiment,proving necessity and reliability of the modeling.The accuracy of the numerical method is verified by comparing with the motion solved by optical flow method.The accuracy improvement effect of the model is confirmed for the reconstruction of the standard sphere.Also,motion outliers of moving object edge is studied,and the shortcomings of outliers location based on modulation and phase are analyzed while outlier location based on motion distribution is recommended.Experiments show that the location of outliers is accurate.3.Based on the research of before-mentioned models and algorithms,a 3-D human face reconstruction system is set up.The hardware composition,system model and software architecture of the system are introduced,and the results of face reconstruction are shown.