The Study Of Central Ningxia Arid Zones's Desertification System Based On Component GIS

Firstly,this paper introduces GIS theory and component-based technology, then gives the detail of Central dry area desertification system was actualized accoding to the central dry area condition in NingXia. this system use Visual Basic as front development tool , integrate database,multimedia,virtual reality,component technology , combinate MapObjects and GeoLod 4.0 control technique etc. In the process of development,this paper propose some solutions to solve the issues of three-dimensional data model and large-scale dynamic 3 D roaming of Massive Data in allution to GIS research and application.Three-dimensional data model and data structure are one of foucses and difficulties for GIS theory research and application. This system solve this problem through integrating virtual reality based on object and GIS technology which sharing the same data structure. This data model adopt a data structure that can manage vector data and the grid data.. In order to avoid the trouble of disposal for separating both, this model also take a centralization of management to these data, such as DEM,DOM,CGS,virtual object,multimedia,etc.Nowadays the bottleneck of GIS applicaion is large-scale dynamic 3 D roaming of Massive Data. this system solve perfectly large range multi-scale seamless roaming problem by using pyramid data structure and dynamic loading and gradual descripting data technology. Thus system can autoload diffirent level's data in according to scope for display.LOD technology is one critical technology for implementing large-scale dynamic 3 D roaming of Massive Data .System organize availably all kinds of relative datas and create a uniform spatial index according to geographic distribution to achive the purpose of quicking the survey of the large range multi-scale seamless roaming.