Research On Precision Of Surface Subsidence Monitored By 3D Laser Scanning Technology

At present,study on the precision of 3D laser scanning is mainly focused on precision of angle measuring,range measuring and model etc.In order to obtain the actual precision of 3D laser scanning technology in surface deformation monitoring,guide the design of surface deformation monitoring scheme,a flat concrete floor,a flat lawn,a sloping lawn,and a hillside are selected as 4 experimental sites with different terrains,obtain their surface point cloud data by 3D laser scanner,model the data by regular grid DEM model based on kriging method,then study the influence of point cloud density,station distance,noise and terrain complexity on precision of surface subsidence precision after DEM modeling.The main research results are as follows:(1)Data processing results show that the influence of point cloud density on the subsidence precision is not obvious,while station distance is the dominant factor affecting subsidence precision;the influence of noise on subsidence precision is simulated by introducing elevation random error in original point cloud data,which can be used to guide the selection of appropriate point cloud denoising method;The influence of terrain complexity on the subsidence precision is analyzed quantitatively by curvature,which can be used to determine whether the instrument meets the monitoring precision requirements.(2)Combined with the surface subsidence monitoring precision and point cloud denoising requirements,the relationship between the maximum station distance and point cloud density is studied;research show that the measured subsidence precision after DEM modeling generally can reach the instrument elevation theoretical precision,and optimal precision of surface subsidence precision after DEM modeling can reach submillimeter level.(3)According to the above results,control the influence of noise on the subsidence precision within 1mm,when it can be concluded that the instrument can meet the requirement of measuring precision,the appropriate station distance can be selected according to the relationship between the maximum station distance and point cloud density,then appropriately deduce scanning point cloud density to save measurement time,that can be used to guide the design of the most economical surface deformation monitoring scheme.