Three Dimensional Space-time Expression Of City Spatial Changes Based On TGIS

With the rapid development of our economy, great changes have taken place in city space structure. The changes effectively improved people’s living conditions, at the same time, they also brought pressure and impact to traffic and environment, etc. Relying on the natural science fund and geological survey project, this article studied time and space visual expression of city spatial changes based on the temporal geographical information te chnology respectively from the lateral pattern change represented by buildings and the longitudinal change of the surface subsidence is given priority to. Hope it can provide reference for city planning and construction and sustainable development. The main achievements:1. This paper abstracted city features with the aid of object model method and analyzed the change characteristics of geographic entity. This article divided the life course of object entities into three change stages, that is emergence, existence and extinction. And it expressed the entities’ changes based on object model. Then, this paper built 3d models of city buildings by using C ity Engine. Finally, it organized models of city buildings based on multi-base and multi- file states with amendments model, and confirmed the rationality of selection by comparing information of data storage, scheduling process, retrieval efficiency of different spatio-temporal data models.2. The surface subsidence, both from the space domain and time domain shows a tendency of continuous change. This paper found that the study area obvious has subsidence area and the stable region through the analysis of the characteristics of In SAR deformation data. In order to improve the efficiency of three dimensional space-time visualization, this article built one model for stable area and built several models for subsidence area according to its time sequence. And it organized models of city surface in different time based on snapshot sequence model, and realized the continuous visual expression of time and space on the surface of the earth.3. Based on Visual Studio 2010, using C# language called Arc Engine component, this paper realized the three-dimensional spatio-temporal dynamic expression of the urban spatial pattern change represented by buildings and land subsidence by designing the timeline, and analyzed the changes of the urban space based on visualization results.