Study Of Optimization Strategies For P2P Oriented3D GIS

Currently the "Digital Earth" as a hot issue creates the great improvement from2D vision to3D, and is making the3D vitural earth to be a widely used geospatial information services platform. But the problems between the higher data demond for the large scale scene and the limited store space of the customers, are however becoming more and more serious, while the data size of GIS is growing up. The speed of data transmission from server to customer is limited by many reasons, such as bad network performance and server errors, while the abilities of the peers are not fully pursued. Thus the loading time plays most important role for the scene creation in3D GIS.Peer to peer computing technology is not a new method, but totally different from the C/S mode. It smartly makes the separated peers connected as a whole class and takes fully advantage of the idle resources in the networks, which makes the traditional C/S mode into a equal network, i.e. each peer not only provideds services to others as a server, but also gets benefit from other peers.3D GIS is using the P2P architecture to updata data transmission and the performance of3D. But P2P technology has its problems in many ways, such as unmatched data organization is not suitable for the3D GIS, discreted data transmission disorders the data loading and the GIS data cache strategies is not suitable for the p2p netwok. This paper focus on the topic of optimization strategies for P2P oriented3D GIS, studies the data organization, transmission and schedule. The study presents a more systematic and completed research result, and thus to improve and enrich the geospatial theory and technology about the combination of P2P and3D GIS.The main content this thesis studies is as follows:1. This paper talks about the necessity, feasibility and basic theory to studying P2P based3D GIS optimization and discusses the related concepts.2. Focusing on the characteristic of P2P and3D GIS data, this paper gives the data size based skewed quadtree method to divide the data. Studying the organization, it gives the mehod of chargement for the different data layering, analsises the special characteristic to deblock different type of3D GIS data to fit the requirement of P2P.3. This paper analyses the data distribution of3D GIS, compares the classic network architecture in P2PGIS, and gives optimization strategies to fix the shortcoming: using webservice based method to communicate with other peers,using mixed mode in hierarchical p2p networks, designing P2P plugin to fit the different usage and giving P2P and KML based geospatial information serive model.4. This paper consults data schedule of quadtree method, gives skewed quadtree query method. Then the paper mentions the the strategies of data downloading based on the important degree to arrange the schedule of different type of3D GIS data and the strategies of dynamic coordinating. The paper then takes the active cache method and P2P connection pool to shorten the waiting time and hot block based active downloading to expand the backup of data.5. This paper focuses on the problems of tranditional3D geospatial information services project, gives P2P based method to update the experimental architecture with en example of3D plan and management system. The test of result between C/S and P2P mode shows the advangement in P2P, then the simulation of skewed quadtree and peer group method proves the model.