Application Research Of Vehicle Mobile Mapping System In Facade Survey

Building elevation survey,which can reflect the position and size of each part of the building on the elevation,is an indispensable part of building a digital city,and also a key part of the three-dimensional city modeling.It is also widely used in daily life,building reconstruction,expansion,lighting engineering and so on will involve elevation measurement.The vehicle mounted mobile measurement system can accurately obtain the 3D coordinate data of the complete facade of the building,solve the problem of irregular facade measurement which is difficult to be solved by traditional measurement,and has the characteristics of high speed and efficiency.Based on the mobile measurement technology,this paper studies the technology process and method of building elevation measurement.1.According to the spatial position relationship of each sensor in the vehicle mobile measurement system,the positioning model is derived.Based on the analysis of the error sources of vehicle mobile measurement and the positioning model,the influence of various errors on the overall measurement accuracy of the system is quantitatively analyzed.2.Due to the technical characteristics of the vehicle borne mobile measurement system and the complexity of the surrounding environment of the building,there will inevitably be cavities in the process of data collection.In this paper,three-dimensional laser scanning technology or close range photogrammetry technology is used to supplement the data in the cavity area and generate the point cloud data in the free coordinate system of the cavity part.Based on the ICP algorithm,the hole points will be Cloud data and vehicle point cloud data are fused to obtain the complete point cloud of building facade.3.Through practical application,verify the feasibility of vehicle mobile measurement system in elevation measurement engineering.Based on the site environment design and collection scheme of a facade project in Jiaonan,the data collection process is clarified,the hollow point cloud data is obtained by the foundation 3D laser scanning technology,and the hollow fusion with the vehicle point cloud data is realized based on the ICP point cloud splicing algorithm to obtain the complete point cloud of the building facade.The total station is used for field measurement to compare the accuracy of point cloud.Finally,the elevation result data is extracted from point cloud by MicroStation data processing software.