Research And Application Of 3D Measurement Technology Based On Structured Light And Binocular Vision

In recent years,the number of patients with dental caries has increased significantly in China,and the demand for oral restoration is increasing.Digital three-dimensional oral measurement can help doctors quickly fulfil the task of oral restoration.Therefore,how to achieve high-speed and high-precision 3D measurement of dental model under the premise of low cost has become a research hotspot.In this thesis,the combination and optimization of structured light three-dimensional measurement technology and binocular stereo vision method to further improve the reconstruction accuracy of dental model has important research significance.The main contents of this thesis are as follows:(1)Improved ordered periods phase shift algorithm based on Gray code.The ordered periods phase shift algorithm only needs to project four fringe patterns to obtain highprecision three-dimensional measurement results.However,for the dental model,the algorithm still can not accurately measure the protrusions and pits on the occlusal surface of the crown.In addition,the design of the algorithm is complex,so it is difficult to extend the number of period directly.In this thesis,an improved ordered period phase shift algorithm based on Gray code is proposed.When only one gray code pattern is added,the periodic number of ordered period phase shift algorithm is expanded to twice.Experiments have proved that the method is more detailed in three-dimensional reconstruction of dental model,has smaller relative error in three-dimensional measurement,and improves the precision of the three-dimensional measurement.(2)Improved ordered period phase shift algorithm based on binocular stereo vision.Because the ordered period phase shift algorithm uses pixel value to identify tuples,there will be ambiguity of series judgment at the junction of fringe segments,which makes the measurement results appear banded mutation.In this thesis,we use the stereo matching measurement to deduce the absolute phase and period series of each pixel.Then,the period series in the ordered period phase shift algorithm can be corrected by using it,so as to correct the stripe mutation.Experimental results show that this method can effectively improve the strip mutation problem in the ordered period phase shift algorithm,and improve the accuracy of three-dimensional reconstruction.(3)Design and Implementation of dental model 3D scanning application system.Based on the three-dimensional measurement technology of binocular stereo vision and ordered period phase shift,a dental model scanning application system is designed and implemented,which is used with binocular structured light hardware platform.The system provides the functions of parameter calibration,3D point cloud computing,3D point cloud management and so on,which can be used to realize the 3D reconstruction of dental model conveniently and quickly.