Map-Sheeted TIN Editing Along Railways For Pre-Construction Visualization

DEM(Digital Elevation Model)is the basis of building a virtual geographic scene.When constructing a virtual scene that includes infrastructure such as railways and highways,tools should be provided to reconstructing the terrain,basically including filling and excavation.In order to realistically demonstrate the impact of railway construction on the terrain in a 3D virtual scene,and to construct a complete virtual railway scene containing roadbeds,slopes,tunnels,bridges,it is necessary to reconstruct the terrain after the railway route selection or in the interactive railway route selection design,which makes it possible for the technicians to intuitively understand the influence of the environment along the route,the type of earthwork construction,construction scale,and the cost of railway construction.Since the raster terrain data cannot accurately represent the features of earth surface,grid DEMs cannot accurately represent the railway feature line such as the subgrade boundary,the original smooth subgrade boundary will the serrated,which also leads to problems to match with terrain.Therefore,the construction and transformation of the terrain model along the railway should adopt Triangulated Irregular Network(TIN)model.In this thesis,TIN model is used for terrain modeling and virtual reconstruction along the railway.Based on the previous research,this thesis proposed a method of TIN-based terrain framing modification along the railway,aiming to provide solutions of parallel processing of framing and improving the real-time performance of large-scale terrain virtual reconstruction along the railway.The implements of the method are based on ArcGIS Engine.The realization uses the triangulation network method with boundary line constraints of the TIN data model in ArcGIS Engine to ensure the preservation of terrain features.The method of line segmentation and terrain framing is used to achieve the requirements of terrain modification.In this thesis,the experiment of the proposed method is carried out,and the experiment of terrain modification is carried out to verify the feasibility,effectiveness and correctness of the proposed method.