Research On Extracting Railway Centerline And Plane Linear Fitting Method For Re-surveying Of The Existing Railway Based On Point Cloud Data

The survey and maintenance of the existing railway is an important means to ensure the safe operation of the railway.The re-surveying work of the existing railway provides basic data for its survey and maintenance.The traditional re-surveying methods have problems such as large workload,low work efficiency,and hidden safety hazards.Therefore,how to quickly and efficiently perform re-surveying of the existing railway has become a hot topic in current research.The Vehicle Li DAR technology can quickly,accurately,in real time,and dynamically obtain the three-dimensional geometric information of the existing railway and its surrounding environment,and has been widely promoted and applied in re-surveying of the existing railway.In this paper,for the purpose of extract the railway centerline and plane linear fitting optimizations which using the Vehicle Li DAR point cloud data to achieve it.The research is focused on the extraction of railway key geometric information.Firstly,the paper introduce the composition,measurement principle,point cloud data features,organization form and data collection operation process of the Vehicle Li DAR system.Based on a comprehensive analysis of the advantages,disadvantages,applicable scenarios and time complexity of the existing filtering algorithm,taking into account the railway scene point cloud data is spatially linearly distributed,and the POS data of the Li DAR system is applied to the railway scene filtering to separate the railway point cloud data.On the basis of filtering,a general method for extracting the railway centerline based on the automatic tracking of seed points on the top surface of the railway is proposed;Therefore,a method for extracting the centerline of the railway considering the reflection intensity of the railway is proposed.The methods achieved high-precision extraction of the railway centerline;and on this basis,the plane linear segmentation method that combines the characteristics of linearity and curvature variation characteristics is used to determine the plane linear section to which each measurement point belongs;and iterative calculation is carried out through the corresponding orthogonal least squares fitting model,so as to obtain the accurate position of the feature point and the plane linear parameters.Finally,on the premise of satisfying the linear design specifications and other constraints,the radius and the length of the spiral are optimized to fit as closely as possible with the existing linear plane,so as to minimize the amount of plane adjustment.According to the engineering example data verification,the railway point cloud filtering method based on POS data can quickly and completely retain the railway point cloud,the extracted railway centerline has high accuracy,the planar linear segmentation results are more accurate,and the optimized plane alignment parameters meet the requirements of relevant specifications and meet the actual engineering needs,which proves the feasibility and reliability of Vehicle Li DAR point cloud data applied to railway centerline extraction and plane line fitting in the re-surveying of existing railway.