Design And Implementation Of 3D Visualization GIS Platform Based On World Wind

Since the beginning of the 21 st century,with the rapid development of information technology,the information age has come.Information is more widely used in various fields.GIS(Geographic Information System)is gradually changing from 2d GIS to 3d GIS.On the one hand,the development technology of 2d GIS and related hardware and software facilities have been improved.On the other hand,due to the increasing demand for 3d information,3d GIS based on 3d visualization technology still has a large development space.At present,most 3d visualization GIS platforms have the problems such as the client need to be downloaded,poor scalability and high cost.As an open source framework for 3d GIS front-end,World Wind only provides a 3d virtual earth(for 3d data display and simple interactive operation),but does not provide SDK package for secondary development.Based on Web GL technology,developers need to understand the underlying development principles and spatial analysis related functional algorithms,in order to realize spatial operations and spatial analysis functions in the way of semi-low-level development.Based on the World Wind open source framework,this thesis realizes the design and development of 3d visual GIS platform.The main work and achievements include the following three aspects:(1)firstly,the overall architecture is determined according to the overall requirements and functional modules of the platform.The 3d visual GIS platform is divided into presentation layer,middle layer,service layer and data layer by using B/S mode,at that the architecture of each layer is designed in detail.Secondly,the platform scene browsing,information query,spatial analysis,data sharing and other functional modules are designed,with the focus on detailed improvement of model loading and flight roaming functions.Finally,the interface style of the platform is determined and the design of the 3d visual GIS platform is preliminarily completed.(2)based on the modular and hierarchical development ideas of the 3d visual GIS platform,the development of functional modules such as scene browsing,information query,spatial analysis and data sharing has been completed.In order to solve the problem of slow loading and rendering speed of scene 3d model,the BSP binary space partition algorithm is improved and the model single loading and batch loading methods are realized.In order to solve the problem that the scene cannot be browsed-over at any Angle,the flight roaming method of the scene camera is improved and realized based on the interpolation algorithm of cubic spline function.(3)the 3d visualization GIS platform is preliminarily applied to the 3d visualization of the campus,which demonstrates the functions such as flight tour,model query,attribute query and spatial computation.The application shows that the 3d visual GIS platform based on World Wind loads the model quickly,the flight roaming effect is smooth,and the operation is stable.