Study On Three-dimensional Measurement Method Of High Reflectivity Metal Surface

The structured light method has the features of convenient data storage and high precision when performing three-dimensional measurements.It is often used in the highprecision measurement and feature recognition in the industrial field.However,the application of this method is related to the optical reflection properties of the metal surface to be tested.For the metal surface to be tested,the optical reflection properties of each area on their surface are very different,resulting in inaccurate solution phase in the saturated pixel area of the collected image,and the underexposed pixel area brings low signal-to-noise ratio,resulting in flying points,point cloud holes and other problems in the high reflectivity area.The high reflectivity of object surface poses a huge challenge when we use structured light for 3D measurement.This article researches effective methods of high reflectivity surfaces commonly used at home and abroad,and studies the system calibration,high reflectivity surface reflection model,dynamic phase separation high reflection suppression method,point cloud registration fusion method,this method establishes the matching relationship through phase information,system construction,etc.,so as to realize the three-dimensional measurement of high reflectivity metal surface.The specific research work of this paper is as follows:Firstly,aiming at the local pixel saturation phenomenon of high reflectivity metal surface during acquisition.Analyzed the schematic diagram of the reflected light component of the high-reflectivity metal surface,and judged the phase error from the component of the reflected light.According to the source of phase error,starting with the multi-step phase-shifting phase-shifting formula,and by analyzing how the multi-step phase shifting method is realized,a dynamic phase shifting method is proposed to improve the reconstruction of high-reflectivity metals.By introducing the overexposure factor,the number of phase-shifting diagrams involved in the calculation is different,so that the overexposure phase-shifting diagram does not participate in the phase calculation,The phase error caused by overexposure is filtered out by using the method of non fixed step phase shift and auxiliary fringe.In order to prevent the phase value from being solved due to too many saturated pixels,a phase solution protection strategy is proposed.Finally,the feasibility of dynamic phase separation highlight suppression method is verified by comparative analysis experiments.Secondly,the reconstruction experimental results of dynamic dephasing highlight suppression method are analyzed.Aiming at the situation of point cloud holes and flying points in a small part of the area,in order to improve the above problems,a point cloud fusion method that establishes a matching correspondence relationship through phase information is proposed,and a multi view point cloud registration fusion structured light3 D reconstruction system with two cameras using one projector is designed.In this method,the edge contour is extracted to fit the center pixel of the calibration plate image,the phase value of the pixel is calculated by the phase shift method,and then the center point clouds of the calibration plate of the left and right cameras are reconstructed respectively.With the help of the phase value mapping of the pixels in the left and right images,the matching relationship of the three-dimensional point pair is established.The registration obtains the positional relationship of the two cameras,and the point cloud data of the two groups are eliminated and fused according to certain rules.Through the perspective of the left and right cameras,the saturation pixels of the high reflectivity object surface are different,and the holes and flying points are repaired by registration and fusion.Then,based on the model of the measurement system,the corresponding relationship between the pixel index information and the coordinate information of the object to be measured is established,and the corresponding relationship between the coordinate information and phase information of the object to be measured is established.Finally,the relative position relationship of the two devices is obtained.Then the camera and system calibration experiment are performed on the two structured light systems,and finally the camera internal parameter matrix information,distortion parameters and system coefficients are calculated.Finally,a three-dimensional reconstruction system of high reflectivity object surface is built.The feasibility of the dynamic phase unwrapping highlight suppression method is verified by using different phase-shifting steps.Compared with the adaptive projection intensity adjustment method,the accuracy and improvement measures of this method after three-dimensional reconstruction are analyzed.Next,the quality of the metal point cloud to be measured reconstructed by this method is improved,a point cloud registration and fusion method is performed on the two systems.The three-dimensional reconstruction experiments of some standard blocks and high reflectivity reflectors are carried out to verify the feasibility of this method and measurement system.