The Study Of Three-dimensional Measurement Method Based On Singular Operator And The Technology Of Shortest Path Search

In the field of non-contact Three-dimensional(3D)measurement,encoded structured light method has been the research focus of researchers.The encoding method which combines Gray code and line shift stripe has been widely used due to its accurate measurement,high sampling density and high resolution.However,Therefore,in this paper,we study the 3D measurement method which combines the Gray code and line shift stripe,and proposes the shortest path search technology based on edge singular operator and central singular operator to detect the Gray code edge and localize the line shift stripe,respectively.This can improve the 3D measurement accuracy.The main work of this paper is as follows.First,we study the shortest path search method and the singular operator of the detection of Gray code edge and line shift stripe center.By analyzing the signal characteristics of Gray code edge and line shift stripe center,we design edge detection singular operator for Gray code edge and build the edge cost function,and design center detection singular operator for line shift stripe center and build the edge cost function.Meanwhile the method of calculating the minimum energy map using the technology of shortest path search based on the Euler distance constraint and the fast moving algorithm is given,and the method of locating the Gray code edge and line shift stripe center by automatic tracking of shortest path search is given.Second,we build the 3D measurement system.Based on the 3D measurement principle,encoding and decoding principle,the mathematical model of 3D measurement system is constructed.We chose the equipment and build the 3D measurement system platform,and calibrate the camera and projector on the platform.Finally,we analyze the accuracy of the proposed edge detection and center localization methods,and do experiments with the proposed methods.According to the straightness,parallelism and equidistance of fitting lines,we locate the Gray code edge with different pixel width.Compared with the intersecting point method,the proposed method has higher positioning accuracy,and the locating error is less than 0.350 pixel.In the case of 4-pixel line shift stripe center localization,the proposed method is more accurate than the gray gravity method,and the error is less than 0.150 pixel.The average error for the standard plane is0.201 mm.Finally,for the 3D surface measurement of the sphere and the vase,the proposed method can reflect the surface shape and texture characteristics of the objects more smoothly.