Algorithm Research For Disposing Of Spatial Data In Geographic Information System

Disposing of spatial data is always one of researching fields in GIS. Three parts have been researched which are the switchover of data format, elliptic window line segment-clipping and the method for updating local topological relation.This thesis has three parts. The first part, the information of the dxf file has been analyzed detailed. The object-oriented programming technology has been adopted for manipulating the dxf file of the module that is for the switchover of data format. In this part, I have progressed zealously attempt in analytic method and realizing technique.In the second part, many line segment-clipping algorithms for clipping windows that have rectilinear and curvilinear border had been analyzed synthetically. Whereas special effective line segment-clipping algorithm for elliptic window had not been presented, integrating the advantages of algorithm for rectangle and elliptic window, and by effectively reducing operations for acquiring point of intersection, an double-quick line segment-clipping algorithm for elliptic window is established by analyzing the base elliptic character completely.In the third part, contraposing the status quo of massive data and slow speed, and by the elicitation of minimum boundary rectangle, a new method for updating local topological relation in GIS has been applied for updating topological relation.