The Research And Application Of The Map Conflation And The Spatial Inquiry

The geographical information system is the integration of computer graphics, digital image prcessing and database management system. It can combine spatial data with attribute data efficiently, and provide a kind of visible query method.The paper mainly researches the following two contents: one is the conflation of the vector map and the other is the spatial query.In order to realize the conflation between the map sheets effectively, the map sheets based on the point feature and the line feature are conflated by using the method of the attribute matching and the distance matching in the paper. We concentrate on researching and discussing the map sheet conflation based on the line feature, that is, we set a suitable threshold value in a range, which lows greatly the time complexity of the conflation. The algorithm's feasibility is verified by an example.The geographical information system has been widely used in transportation, the civil defence and the urban planning which often refer to the shortest path's search. The paper improves the Dijskstra in two ways: one is the storage structure, which uses the undigraph and the adjacent list to store the unoriented topography and to compress the data's memory space, and the other is the performance, that is, the sequent nodes recorded by a node need to be updated each time according to the characteristic of the adjacent list storing the undigraph. In this way, the performance of the original algorithm has been improved quickly.