GIS-Based Spatial Data Query Technology And Its Application

With the fast development of the computer technology and the expanding of the social demand, the application of GIS becomes more and more popular. The query of large amount of spatial data is the key problem in the construction of GIS systems.This dissertation first introduces spatial data characteristics, and describes spatial data structure and models. Also, the arithmetic of the spatial data is discussed. This thesis suggests two methods to improve the query, one is to optimize the query language and the other one is to choose the better spatial database index technique. Taking notice of the disadvantages and the data structures, algorithms of existing spatial indexes, the thesis introduces a spatial index structure named QR-tree based on quad-tree and R-tree. The research indicates that QR-tree always demands more storage than R-tree, but it gains better performance in insertion, deletion, and especially searching and the more the amount of spatial data is, the closer the storage cost of QR-tree and R-tree are, the better performance QR-tree has. That is to say, for very large spatial databases, QR-tree processes more superiority than R-tree. Therefore, for applications that must process large volumes of spatial data, such as GIS. The QR-tree index can improve search performance and speed up the response.Based on the QR-tree and the query optimizer, the system"FORMAX"is implemented. The system performance is evaluated next. And finally, some suggestions for the improvement of the application system are given.