The Research On Technology Of Campus Geographic Information System Based On Vector Graphics

With the progress of IT in education, the Digital-Campus project along with its correlative technologies and applications has become the focal point of the research in informatization of university. Campus Geographic Information System(CGIS) is a branch of UGIS, it is aimed at organizing unitedly all the information resource in campus and share them via network in order to serve the activities of education, scientific research, and personnel training, etc. The paper designed a new type of GIS model to fit in the Digital-Campus system and implemented a proptype of it.As a new developing subject, GIS gets widely applied. Because vector graphics are GIS's base of research, then we introduced the data model of the vector graphics, the data structure of the vector graphics and the space relation at first. Through the data structure, it represents the relation between the point and line, the line and surface, the point and surface in the spatial data. With the vector data structure created, we study a lot of spatial analyze arithmetic, such as the shortest path arithmetic. As to the system design, this paper makes a deep insight into the technical aspects in the design and realization of CGIS, Because of using the object oriented structure and relational database, it makes the management of graph data more simple and makes the operation clearly and understandable.The optimizing of query is the focus problem in spatial database and the Nearest Neighbor query problem is difficult in the focuses of GIS. The Reverse Nearest Neighbor problem has been introduced recently. So how to query the RNNs of spatial data effectively has become another focus problem. We have proposed the algorithm of nearest neighbor query of multi-object based on the SR-tree that was distinguished from the existing ones. From the experiment results we can see this algorithm has a good performance even in multi-dimensions. To query the RNNs effectively we develop a new algorithm based on the SRdnn-tree. To compare it with the existing ones, our method has achieved a much better performance. In addition, the bi-directional Dijkstra algorithm and the acceleration of intermediate list are proposed to be the improvement of Dijkstra algorithm. Through validating on a map with a lot of vertexes, the efficiency of the intermediate bi-directional Dijkstra algorithm accelerated by list is generally higher than that of the traditional Dijkstra Algorithm on average.The model-based system implements the basic function of CGIS, and the final part of the paper represents the summary of the study and prediction of the future research.