Research Of 3D Measure System Based On Multi Line Structure Light

With the development of industrial automation and the decrease of the cost of novel optoelectronic device,As well as to the industrial product quality control request is more and more strict.There is a growing demand for 3d inspection of industrial product sizes.The 3d measurement method based on structured light is an important detection method in industry,It has the characteristics of simple system structure,non-contact and high precision,which makes it widely used in product testing,3d modeling,reverse engineering and other directions.In the measurement system,the calibration of the structured light plane is the key part of the system,The calibration precision directly affects the measurement precision of the target object.In order to achieve the goal of rapid and high-precision measuring of different sizes of products,three-dimensional points cloud is used.In this paper,a 3d measuring system based on multiline structured light is studied.A more concise and effective method is proposed for the calibration of single structured light plane.Based on the single structured light plane calibration results,the multi-plane structured light plane calibration algorithm is extended.In addition,the application of nonlinear optimization theory in camera calibration is analyzed and deduced.Finally,the target three-dimensional point cloud acquisition experiment was completed and the accuracy of the experimental results was analyzed.Following jobs are carried out:1.The structure and basic principles of 3D measurement system based on muti-line structured light are analyzed,including camera imaging principle,system 3d measurement principle,camera calibration algorithm and non-linear optimization algorithm and code implementation of these algorithms.2.Research on camera calibration algorithm based on two-dimensional target,Choosing Zhang's calibration method with concise operation and high accuracy.Based on Zhang's calibration method,a single-line structured light calibration method is proposed in this paper.In this method,the structured light plane is calibrated onlywith a free-moving planar checkerboard lattice target.And the calibration process of the optical surface is combined with the calibration process of the camera's internal parameters.In the process of camera calibration,only the intersection line between the light surface and the calibration plate plane is needed to complete the calibration of single structured light surface with high accuracy,and no other equipment or specific conditions are needed.To obtain the three-dimensional point cloud data more quickly.A projector is used to project several light planes onto the surface of the object to form bright and dark stripes.The points on the stripes can be obtained at one time.In this paper,a fast calibration method for multi-line structured light is proposed.After calibrating two specific single-facets by single-line calibration method,a coordinate system is established at the intersection of the two planes.The pose of any light plane in the camera coordinate system is derived by using rotation matrix,and the calibration of multi-line structured light is completed.Finally,each stripe is coded to locate the light surface to which the stripe belongs,and the three-dimensional point cloud data of the object is obtained by combining the position and posture of the specific light surface.4.A three-dimensional measurement system based on structured light is built,and the experiment of acquiring three-dimensional point cloud of the target object(disc)is completed,and the point cloud data of the target object is acquired.The point cloud data are analyzed,and the measurement accuracy of the system is analyzed in three directions of x,y and Z.Data analysis shows that the calibration accuracy of single-line structured light plane can make the measurement error of x,y direction less than 0.04%,and Z direction less than 0.5%.The introduction of multi-line reduces the measurement time and simplifies the system structure.Experiments verify the accuracy of single-light-plane calibration algorithm and feasibility of multi-light-plane calibration algorithm.This method has been adopted and developed by relevant companies.