Research On The Application Of 3D-GIS To Flood Route Visualization Based On ArcGIS And SketchUp

Natural hazards, especially flood disasters, frequently occur in our country and cause serious damage. For some important cities and flood diversion areas, GIS based methods to accurately simulate flooded area, depth and velocity distribution in space and in time are worth for formulating emergence measures and emergency evacuation routes, optimizing the masses flood rescue materials configuration, and assessing dynamic flood loss. However, the two-dimensional GIS system often do not accurately reflect, analyze, and display relevant information in dealing with floods and other natural phenomena. With the development of the three-dimensional GIS and the digital basin, it is important for us to deal with the floods from the three-dimensional space. Compared to traditional forms of two-dimensional GIS, the three-dimensional GIS system gives us a more real, natural and intuitive feel.This paper introduces the theory and the development of 3D-GIS. The principle of the geographic coordinates system, the projection coordinate system and the vertical coordinates system will be expounded, and transformation between the GCS and the PCS will also be involved. The core of spatial data, vector, grid and 3D data model, and their modeling method are discussed. Digital terrain model and digital elevation model are described in this paper, and different terrain modeling methods based on Grid, TIN and contour are also studied. Meanwhile, this paper analyzes and studies the 3D-GIS scene mass data loading and visualization of key technologies. According to the 3D-GIS status and the application in the flood disaster, this paper presents 3D scene based on ArcGIS and SketchUp. In addition, according to three-dimensional model symbolic and Multipatch data model method, this paper has realized data interactive between ArcGIS and SketchUp. The Application based on Globe control and Scene control is successfully realized in this paper. According to the requirement of 3D-GIS flood evolution visualization, this paper provides a method for converting 2D flooded numerical results to spatial data and the conversion process is detailed. Finally, this paper implemented the ArcEngine-based 3D-GIS system including spatial query, terrain analysis, three-dimensional roaming and flood evolution visualization, etc. Furthermore, the 3D-GIS system has been successfully applied in Jingjiang flood diversion area, Foshan Chanheng area and Yichang Yangtze River.