Research On Uncontrolled Self-calibration Method Of Terrestrial Laser Scanner

Three-dimensional laser scanning technology,also known as "actual reproduction technology".It is the method of laser scanning measurement to obtain the threedimensional coordinate data of the surface of the measured object.And by collecting spatial point information,a technical means to quickly establish a three-dimensional image model of the object.This technology is widely used in the protection of ancient buildings,deformation monitoring,geological disasters,tunnel measurement and other technical fields.The three-dimensional laser scanner is a new type of geographic coordinate information acquisition equipment.During its use,its aging and wear will reduce the measurement accuracy of the instrument to a certain extent.Therefore,regular calibration of the accuracy of the instrument becomes particularly necessary.However,the calibration method of the ground 3D laser scanner has not yet formed a complete system,and the existing calibration theory and experimental site cannot easily,quickly,and efficiently achieve the effective verification of the ground 3D laser scanner.The thesis aims to propose a method of uncontrolled self-checking based on planar features,to achieve a high-efficiency and highly automated on-site self-checking of the 3D laser scanner on the ground.The thesis conducts research on the uncontrolled self-checking method based on plane features.The main research contents and work are as follows:(1)Aiming at the problem of how to establish a robust and effective calibration model for the uncontrolled self-check calibration method,by analyzing the main system error sources of the ground three-dimensional laser scanner and based on the point cloud data plane characteristics,the uncontrolled self-check calibration model was established;(2)Aiming at the problem of fast and accurate solution of model parameters for uncontrolled self-checking,the rapid registration and accurate orientation of point cloud data was used to obtain external parameter values and increase model constraints to optimize model parameter solution;(3)Aiming at the problem of weight setting and homonym selection in the process of uncontrolled self-check calibration,the correlation between various system errors was analyzed to verify whether the weight setting was correct and the homonym selection was reasonable;(4)In order to quantify and compare the plane fitting accuracy of the same name before and after the uncontrolled self-check,the root-mean-square error RMSE of the point-to-face distance was introduced to measure the deviation of the true value from the observed value,and the uncontrolled self-check based on the plane characteristics was verified The effectiveness of the calibration method.In this paper,through the example verification of the uncontrolled self-checking method,the point cloud data collected by the indoor and outdoor checkout fields is used to solve the parameters of the uncontrolled self-checking model.By analyzing the correlation between various system errors,The correlation between the system error parameters of the uncontrolled self-check calibration is between 0.0-0.2 and 0.0-0.25,which verifies that the weight setting of the parameter calculation process of the uncontrolled self-check calibration is correct and the selection of the same name is reasonable;Before and after the self-check calibration,the plane fitting accuracy of the corresponding plane with the same name is increased,and the indoor and outdoor plane fitting accuracy of the same plane is increased by 45.50% and 42.06% on average.Effective verification of the instrument.The indoor and outdoor self-checking only adds the system error parameter correction.The plane fitting accuracy increases by 38.48% and 33.12% on average.The improvement of the plane fitting accuracy of the samenamed surface after self-checking without control on the surface is mainly affected by the system error parameter correction.