Study On A Method Of Airborne LiDAR Ranging Ambiguity Correction

As an active detection method,LiDAR can be installed on multiple platforms and integrate different LiDAR scanning systems to perform three-dimensional reconstruction of scanned objects.When the airborne LiDAR is sampling on the ground,it is necessary to set different scanning parameter indicators according to the task requirements of the scanning area,and generate a 3D laser point cloud with the POS data to meet the modeling requirements of the measuring area task.In the selection of scanning parameters,especially the limitation of PRR,multiple around time phenomenon will occur,resulting in ambiguity ranging,and there will be different degrees of loss of scanning strip width,point cloud density and number of point clouds for each flight.In high-precision 3D modeling,the point cloud density directly affects the quality of the modeling,and the smaller the strip width directly leads to unnecessary flight times.When terrain mapping or construction of 3D power line model,limited by point cloud density and scanning width,resulting in insufficient modeling accuracy.In this context,based on the research status and solutions,this paper follows the concept of radar multiple around time to solve the problem of point cloud ranging ambiguity.The main research contents of this paper are as follows:(1)Airborne LiDAR system integration and 3D point cloud generation principle.Learning the research status and solutions of the airborne LiDAR on the ambiguity point cloud problem.Lidar internal structure,pulse ranging principle,and integrated components of airborne LiDAR and coordinate system conversion.Analysis of data acquisition method and POS data processing and accuracy evaluation under airborne LiDAR integrated system.(2)Extracting ambiguity point cloud based on a new filtering algorithm.According to the problem of ambiguity point cloud,a new filtering algorithm,namely the Gaussian fitting filtering algorithm is proposed.The Gaussian function is used to fit the distribution of the three-dimensional point cloud of single scan line using time and elevation.The middle value is the threshold of the separated ambiguity point cloud.The method can automatically classify and extract the ambiguity point cloud in different scanning terrains,and finally perform the point cloud partitioning according to the point cloud normal vector.(3)Ambiguity point cloud ranging and time correction.Based on the correspondence of time between the extracted fuzzy point cloud and the original sampling point cloud,the ranging ambiguity record appearing in the original sampling point cloud is searched by using the ambiguity point cloud time,and then the original is based on the principle of the maximum ranging integral times caused by the multiple around time phenomenon.The ranging and time of the scanned data is corrected,then finally the 3D laser point cloud is regenerated.The experimental results show that the research method of this paper can effectively solve the problem of ranging ambiguity point cloud caused by multiple around time,effectively increase the strip width of point cloud scanning and density of point cloud.