With The Grid System Of Web Gis Research

Geographical Information System - GIS - is a geographical research technology that was quickly boomed. It is a comprehensive science of computer science, mapping and remote sensing, geography, environmental science, space science, information and management science.Web GIS Is hotspot and tendency of GIS In traffic, power network and many otherfields, WebGIS provides users dynamicly and visually geographical information which can collect, store, analyzes and visually expresses spatial data. WebGIS is a combination of GIS and WWW. It expands the application field of GIS,and makes GIS a very popular information management tool.Based on the practical request of power network, this paper first analyzes general techniques to realize Web GIS system: CGI,Plug-in, ActiveX, Java Applet. Then it evaluate them from many aspects. Finally the conclusion was drawn that in the present stage and under existing condition,the implementation method based on ActiveX is the most suitable way to build Web GIS system.This paper defines a way which takes 2D geometry data used in power network's special situation in consideration to embody spatial data in relational database,and discusses on how to set spatial index in this model.In the field of processsing of spatial data, this paper uses spatial object to represent spatial data,advances a object model to organize and dispose spatial object in relational database.This model assembles spatial data in objects and sets of objects at liberty and encapsulate operations of spatial objects in objects,so spatial objects can be used flexibly.This framework which acts as GIS data accessing layer provide effective support for the run of upper layer.This paper puts forwards a new solution to Integration and share of GIS Data in the scope of the internet.lt uses XML and Web Services to build a Web-Based Geospatial Service Platform. The pape describe these aspects particularly:architecture of Web GIS which is based on Web Services,basic protocol used in each level of Web GIS Services,how to put Web GIS Services into practice by implement it with some interfaces.This paper discusses on a way to develop ActiveX control used in Web GIS and develops a efficient and applied ActiveX control which can reflect special demand of power network.00 idea is embodied full-scale in the debelopping of ActiveX control and its interface.When programmer is developping UI page,the events, methods and attributes of this ActiveX control can be used to achieve a ideal effect.In common Internet Browser,client terminal can use this Web GIS ActiveX control to realize the funtion of display and operation.