Research On Key Technology Of Middle-Altitude LiDAR Surveying And Mapping System Based On The Stripe Array Detection

Compared with the traditional commercial LiDAR system,the high-precision LiDAR technology based on array detection system is a new LiDAR imaging system,which has very important military significance and practical application value.Based on the development of 3D imaging LiDAR mapping technology,this paper studies the key technology in the development of the new system LiDAR system which is based on stripe array detection,aiming at finding a systematic solution.To achieve the complete ability of the new LiDAR system based on stripe array detection,the system construction,3D imaging LiDAR mapping system principle,model error analysis,simulation design,system calibration,data processing and the related key techniques are studied systematically,and the performance and system capability of the theory and algorithm is are verified by experiments.The main work and innovations of this paper are as follows:1.Originated from the photogrammetric results accuracy requirements and according to the imaging principle and technical features of 3D imaging LiDAR surveying system based on stripe array detection,the definitions and transition relations between various coordinates are discussed,and the error model of the system positioning is studied and derived.The influence of error sources such as laser ranging error,scanning angle error,atmospheric influence distance-error,position-attitude measurement error,instrument placement error,time synchronization error and data preprocessing error on the positioning accuracy of the system is analyzed.The error distribution of the results are given to determine the overall accuracy of index system,which lays a geometric model foundation and provides theoretical support for the development of 3D imaging LiDAR surveying system based on stripe array detection.2.According to the performance requirements of middle-altitude surveying and mapping,the system location error model and the LiDAR imaging equation,the key parameters involved in the system are determined from the aspects of bandwidth,distance,laser scanning speed,LiDAR range and laser energy design,etc..In view of the overall design requirements,the ground laser point coverage performance and the system positioning accuracy under different terrain conditions such as plain,hilly and mountainous areas are simulated and verified,based on the imaging principle of stripe array detection and the theory of the "broom" scanning mapping and according to the design requirements of the system.The design parameters,which are given through simulation,not only provide scientific reference and design basis for development of the new LiDAR system,but also provide an effective technical approach for the optimization of system design.3.In accordance with the specification of the system overall accuracy and error distribution results,the problems that need to be solved in the technical difficulty and calibration of 18 km high-altitude surveying and mapping are analyzed.A static calibration and dynamic calibration scheme for mid-altitude airborne lidar system is designed and put forward.The design scheme of the circular static scaler combined with the dynamic scaler of Pyramid and artificial square platform is proposed.The detailed design of the selection of the calibration site,the layout of the GPS datum station,the setting of the scaler and the planning of the fixed flight route,etc.are completed.Then,this paper researches and implements the relevant calibration algorithms,and carries out the static airborne the 3D imaging LiDAR mapping system calibration tests and dynamic flight tests,which verify the correctness and feasibility of the calibration method of the technology.4.Originated from capability requirements of airborne LiDAR data processing in the new system,this paper designs working process and data processing flow of the system,confirms the system calibration and error correction scheme,puts forward some methods and ways of data preprocessing aiming at the high-altitude lidar.The three-dimensional coordinate calculation model based on the GPS/IMU data of same platform is derived.On this basis,the error correction of the range and direction angle is corrected by the static geometric correction,the dynamic geometric correction and the correction of the atmospheric influence of the laser radar.And the algorithms of the 3D point cloud computation and error correction are realized with high precision.The experiment shows that the point cloud data by preconditioning can satisfy the using requirements.5.On the basis of reviewing and sorting out the current filtering algorithms of LiDAR point cloud,the characteristics and limitations of the results of the existing filtering algorithms are analyzed and compared,and an adaptive filtering strategy and method is proposed to improve the adaptability of the filtering algorithm to different terrain.The adaptive processing flow of the point cloud filtering is designed.And the adaptive method of point cloud filtering is given based on the region segmentation algorithm and comprehensive filtering model.Using Pingel's improved simple morphological filtering algorithm,the paper builds the comprehensive filtering model.The filtering experiments of LiDAR point cloud are designed.Analysis and comparison between the filtering results of the proposed method,the artificial reference results and the direct results of traditional editing morphological filtering algorithm are researched.The experimental results show that the strategy and method proposed in this paper can be applied to the filtering processing of large point cloud data,and the improved effect is achieved.The filtering II class and the total error rate are effectively reduced.The terrain reconstruction results are more in line with the real terrain,and have high practical value.