对等网络环境下三维GIS优化策略研究

发布时间：2018-05-24 13:18

本文选题：对等网 + 三维GIS　；参考：《武汉大学》2013年博士论文

【摘要】：目前热门的“数字地球”实现了从二维到三维的跨越,使得三维虚拟地球已经成为一个应用广泛的地理信息公共服务平台。由于目前GIS的发展具有海量数据特征,并且其数据规模还在急剧增加,而客户端受到存储性能限制,大规模场景数据的需求与用户可用的存储空间的矛盾日益严重。在网络环境中,客户端节点与服务器节点之间的连接速度往往受到网络传输和服务器性能制约,同时存在客户端资源的浪费,因此在三维GIS数据场景显示的整个过程中数据传输消耗时间最长。对等网络(Peer to Peer,P2P)虽然不是一项新兴的技术,但是不同于传统集中式模式,是全新的基于对等网络的架构,非常巧妙的将网络中互不直接相连的客户端节点联系在一起,充分利用客户端节点和局部网络传输的闲置资源,将集中式的由服务器到客户端的传输模式转变成为了无等级差别的分布式传输模式。三维GIS可以利用对等网技术显著提升数据传输速度从而提升三维引擎性能。但使用对等网技术依然存在问题,具体表现在采用对等网文件共享的数据组织模型并不适应于三维GIS；离散的数据调度策略导致三维GIS数据加载顺序的随机性,从而影响三维GIS渲染效率和用户体验；GIS缓存更新策略单一未能考虑到对等网共享。本文结合对等网技术实现对三维GIS的优化,针对性的开展对等网环境下的三维GIS数据组织、传输和调度研究,给出系统、完整的研究成果,从而完善和丰富了将对等网技术应用于三维GIS的优化研究。论文主要研究内容如下： 1.分析基于对等网技术的三维GIS优化技术的必要性、可行性以及理论依据,并对其相关概念进行阐述； 2.根据对等网络中数据传输特点,研究空间数据组织方法,在数据分层组织方面提出参考等级评价机制,在数据分块方面分析组织考虑各种数据类型特点,研究适应对等网传播的分块方式,提出参考数据量的非均匀四叉树网格划分法。 3.分析传统三维GIS数据的发布模式,参考典型对等网GIS的组织结构,研究应用于三维GIS的对等网架构的不足,提出优化策略：采用了基于WEB服务的对等网连接方式；采用混合模式的对等网络架构,采用基于位置和内容的节点双向聚类方法分组;对对等网功能采用插件模式设计,提出了基于对等网和KML的地理空间信息服务模型,实现基于对等网技术的简易升级方法。 4.参考传统均匀网格数据调度方法,提出非均匀网格快速查询方法。在对等网数据下载过程中强调按重要程度实行分层分块传输,采用下载动态协调策略。采用主动缓存优化技术和对等网节点连接缓存技术预读视点周围场景数据,减少场景漫游的数据等待时间：提出基于热点的主动缓存,增加对等网络中数据备份量;研究三维GIS缓存更新策略,提高对等网整体数据共享效果。 5.针对在传统集中式三维地理空间信息服务项目的开发过程中遇到的实际问题,以三维可视化规划管理系统为实例,提出了基于对等网技术的实验性的改进,通过实验对比集中式与对等网式架构的性能差异,指出基于对等网技术三维GIS优化策略可行并且用效。并研究非均匀网格数据划分效果,采用仿真实验验证节点分组效果和主动缓存效果。
[Abstract]:At present, the popular "Digital Earth" has realized the leap from two-dimensional to three-dimensional, making the 3D virtual earth become a widely used public service platform for geographic information. Since the development of GIS has the characteristics of massive data, and its data scale is still increasing rapidly, and the client is restricted by storage performance and large-scale scene. In the network environment, the speed of the connection between the client node and the server node is often restricted by the network transmission and server performance, and there is a waste of the client resource in the network environment. Therefore, the data transmission consumption is consumed in the whole process of the 3D GIS number according to the scene. The longest time.
Peer to Peer (P2P) is not a new technology, but different from the traditional centralized model, it is a new architecture based on peer-to-peer network. It is very clever to link the non directly connected client nodes in the network together, make full use of the idle resources of the client node and local network, and will be centralized. The transfer mode from the server to the client turns into a distributed transmission mode with no hierarchical difference. The three-dimension GIS can improve the data transmission speed and improve the performance of the 3D engine by the peer-to-peer network technology. However, the use of peer-to-peer technology still has problems, which is manifested in the data organization model of sharing the peer-to-peer file. It does not adapt to 3D GIS; discrete data scheduling strategy leads to the randomness of 3D GIS data loading sequence, thus affecting the efficiency of 3D GIS rendering and user experience; GIS cache update strategy is unconsidered for peer-to-peer sharing. In this paper, P2P technology is used to optimize the 3D GIS and to carry out peer to peer environment. The next three dimensional GIS data organization, transmission and scheduling research, the system, the complete research results, thus improving and enriching the application of peer-to-peer technology to 3D GIS optimization research.
The main contents of this paper are as follows:
1. analyze the necessity, feasibility and theoretical basis of 3D GIS optimization technology based on P2P technology, and elaborate its related concepts.
2. according to the characteristics of data transmission in the peer-to-peer network, the method of spatial data organization is studied, and the reference level evaluation mechanism is put forward in the data stratification organization. In the aspect of data partition, the organization takes into account the characteristics of various data types, and studies the partitioned mode adapting to the peer-to-peer network propagation, and puts forward the non uniform four fork tree mesh division method for the reference data.
3. analyze the distribution pattern of traditional 3D GIS data, refer to the organization structure of the typical P2P GIS, and study the deficiency of the peer-to-peer network architecture used in 3D GIS. The optimization strategy is put forward: using the peer-to-peer connection method based on WEB services, using the mixed mode peer-to-peer network architecture, and adopting the bidirectional clustering of nodes based on location and content. The method is divided into groups, and the function of peer-to-peer network is designed by the plug-in model. A geospatial information service model based on peer-to-peer network and KML is proposed, and a simple upgrading method based on peer-to-peer network technology is realized.
4. based on the traditional uniform grid data scheduling method, a fast query method for non-uniform grid is proposed. In the process of data downloading of peer-to-peer network, it emphasizes the implementation of hierarchical and partitioned transmission according to the importance, and adopts the dynamic coordination strategy of downloading. The active cache optimization technique and the peer to peer connection cache technology are used to preview the scene data around the view point, and the data are reduced. The data waiting time for scene roaming: an active cache based on hot spot is proposed to increase the amount of data backup in the P2P network, and the three dimensional GIS cache updating strategy is studied to improve the overall data sharing effect of P2P.
5. in view of the actual problems encountered in the development of the traditional centralized three-dimensional geospatial information service project, the experimental improvement based on peer-to-peer network technology is proposed with the three-dimensional visualization planning management system. The performance difference between the centralized and the peer-to-peer network architecture is compared through experiments, and the three dimensional GI based on P2P technology is pointed out. The S optimization strategy is feasible and effective. It also studies the data partitioning effect of heterogeneous grids, and uses simulation experiments to verify the effect of node grouping and active caching.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P208

【参考文献】