Local Update Research Of Topological Data In Geospatial Data

With the society and economy advancing rapidly and geographic information changing constantly,people's needs for geographic information integrated service have been increasing.Current data and rich contents are playing a predominating role.Therefore,data update is more important than database construction.In essence,updating of geospatial data is a process to change the state and content of spatial entity.The spatial entity changes include the change of geometrical relationship,attribute information and topological relation.The topological relationship,as an important spatial relationship,is of great significance to spatial data's expression,storage,inquiry and analysis.Moreover,the local updating technology of topological relation plays an important role in efficient processing and real-time updating of spatial data.This paper mainly studies the local variation of topological data caused by geographical events.Based on the study of different geographic events,the change of topological relationships among geographic entities is analyzed.The change of topological relation and local topological change caused by the change of geographical events are studied,and the local update of topological relation is realized by the form of geographic events.The main research works are listed as follows:(1)The detailed research is made on the features,classification and application of geospatial data,spatial entities and spatial relations.6 spatial relations existing in point,line and surface are studied.Topological relations contained in each spatial relation are also analyzed.The research is carried out on the building of point-line topological relation,the point-surface topological relation,and on the update operation of node and segmental arc in updating local topological relations.(2)Geographical events occur,must cause the impact on the surrounding geographical elements,the article for each type of geographical events happened before and after the change of the topological relations between the two factors are analyzed,and the changes of the topological data and the change rule of topological relations is analyzed,geographical events essence is around the point,line,face the change of three types of entities.Through to the affected by geographical events between dot,line,face the change of topological relations,and the topological data contrast analysis,to realize the local update research based on the topology of geographical events.Finally according to the topology data,the change rule of node,the segment will be in addition to new events and death outside of geographical events summed up as a combination of new events and extinction events,here depending on the node,the number of segment is increased when new event,the decrease in the number of nodes,segmental arc extinction event.(3)Through the classification of nodes and arcs,the geographical elements of the topology changes are extracted,and the regional scope of topology updating is selected.According to the data of the new,delete operations,the topology of the topology of the data editor,under the new events to add points,add the line operation,the death of the event to delete points,delete the line operation.And the topological atomic operation is used to describe the data change process of topological data during the event of new events and extinction events.(4)Using the method of selecting the range of changing elements and extracting the elements of the topology change,the local elements of the geographical changes of the urban area are updated locally.Select the area where the new event occurred and the area where the fatal event occurred,and update the topology data of the changing feature.