Target Design And Center Positioning Method For Mobile Laser Scanning In Highway Tunnel Scenes

When the mobile laser scanning system scans in highway tunnels,traditional chessboard due to fast speed,resulting in sparse target point clouds,or other moving vehicles that may block some targets,as well as interference from high reflectivity materials on some tunnel walls.which makes it difficult to extract traditional chessboard targets and causes serious center positioning errors.This article analyzes and studies the attributes of laser point clouds,based on the operational characteristics of the mobile mapping system in highway tunnels,a target suitable for mobile scanning on highways was designed,and a highly robust target center precise positioning method was proposed.The research content of this article includes:(1)Target design: firstly,the characteristics of laser point clouds were analyzed through laser scanning experiments,and the effects of target material,color,and laser incidence angle on point cloud properties were studied,combined with the characteristics of highway tunnel moving scanning,a customized planar target suitable for highway tunnel moving scanning was designed.(2)Target center positioning: firstly,combined filtering and shape estimation specific to the design target are used to extract the target point cloud from the scene point cloud,and then the target boundary is extracted using the time distribution characteristics of the target point cloud,then,based on the design target,a standard target boundary template with a center point is generated,and the boundary template is matched with the extracted boundary using the method of tolerating outlier,after successful matching,use the center coordinate of the standard target template as the value for target center positioning to complete target center positioning.Finally,the designed target and matching algorithm in this article were applied to a3.5km long highway tunnel,the method successfully extracted the target and achieved central positioning,verifying the effectiveness of the designed target and positioning algorithm,the analysis of target environmental adaptability,incomplete target positioning,and positioning accuracy was carried out,the analysis results showed that the target in this article has strong adaptability to the environment,this method achieves precise center positioning when the target is partially incomplete,when the target is complete,the center positioning accuracy of this method is about 3cm compared to the centroid method,which has an accuracy improvement of about 2cm compared to the visual method;when the target is incomplete,the center positioning accuracy of the method in this article remains at around 3cm,which improves the center positioning accuracy by 1-4cm compared to the centroid method and visual method.