【作者】 高志敏；

【导师】 姜波；

【作者基本信息】 浙江工商大学 ， 计算机软件与理论， 2011， 硕士

【摘要】 随着Internet技术的快速发展,越来越多的领域采用网络地理信息系统(WebGIS)作为其展示和处理空间信息的手段,它改变了地理信息的获取、传输、发布、共享和应用的方式。网络地理信息系统(WebGIS)是在网络环境下的一种存储、处理和分析地理信息的计算机系统,经过几十年的发展,WebGIS已经能够在更广泛的领域为更多的用户提供空间信息服务。但是从目前WebGIS的国内外的应用和发展现状来看,这项技术尚未成熟。空间数据的多源性和多语义性使得各个系统各自独立,形成了一个个的空间信息孤岛,最终导致地理空间信息不能实现较好的共享。本文在对当前网络地理信息系统(WebGIS)发展和应用的相关研究背景进行分析的基础上,对WebGIS中所应用到的关键技术进行了深入的研究,并将其成功地应用到现代数字社区之中。本文的研究内容主要包括：(1)提出了一种基于四叉树的动态地图标注算法。地图标注问题是WebGIS研究中最基础也是最重要的问题之一。目前已经发表的标注算法有很多,如离散梯度下降算法、启发算法、回溯算法、模拟退火算法等。但其标注效率较低,时间消耗较大。本文在对这些地图标注算法深入研究的基础上,充分利用目前较为先进的软硬件资源,将并行计算技术运用在地图标注算法中,较大地提高了地图标注的效率。(2)提出了一种基于GML技术的空间数据到GML文档的映射方法。在WebGIS发展的初期,HTML (HyperText Markup Language,简称为HTML)是WebGIS中空间信息的主要表达语言。但是,空间数据的内部结构极其复杂,并且还具有多源性、多语义性、多尺度性等特点,因此,HTML无法实现在Internet上空间信息的查询、整合和准确定位。GML是国际OGC组织基于XML制定的用于描述地理空间数据的语言,由于该语言是建立在公共地理模型基础之上,同时,由于GML内在的可传输性和可访问性使得该语言对地理空间数据的共享具有深远的意义。但是,空间数据大都以空间数据库或数据文件方式存储,使得空间数据不能实现真正意义上的共享。因此,本文在对空间数据库和地理标记语言(GML)深入研究的基础上,提出并实现了空间数据向GML转换的方法。(3)提出并设计了Web地图服务模型,并对关键模块进行了实现。本文对OpenLayers地图框架进行了深入的研究和分析,在此基础上提供了地图切片技术的实现,接着对地图缓存技术进行了深入的探讨,最后将该Web地图服务模型成功地应用到现代数字社区之中。更多还原

【Abstract】 With the rapid development of Internet, WebGIS is applied in more and more fields as a way of displaying and processing spatial information, and so it changes the way of getting, transporting, publishing, sharing and using geographic information. WebGIS is a computer system, which stores, processes and analyzes geographic information in the network environment, after several decades of development, WebGIS has already provided spatial information services for more users in wider area. However, from the application and development of the current WebGIS at home and abroad, the technology is not yet mature. The multi-source and more semantic spatial data makes the system independent of each to spatial information silo and geographic information sharing.Based on the analysis of the relevant research background of the application and development of the current WebGIS, This dissertation makes deep study on the key technologies, which is applied in WebGIS, and successfully applies it into modern digital community. This study mostly including:(1) We proposed a dynamic algorithm of map labeling on the basis of the quadtree. Map labeling problem is one of the most elementary and critical problems in the WebGIS research. At present, map labeling algorithms, which has been published, are abundant such as Discrete Gradient algorithm, Heuristic Method algorithm, back-track algorithm and Simulated Annealing algorithm. But their labeling efficiency is very low, and their time loss is very large. This dissertation, based on making deep study on map labeling algorithms, makes the best of the current software and hardware resources, which is much more advanced, and applies parallel computing technology into map labeling algorithm to greatly improve the efficiency of map labeling.(2) We proposed a mapping method of transforming spatial data into GML document on the basis of XML technology. Traditional WebGIS, which is not able to accurately describe internal data structures, takes HTML as the main expression language of spatial information, but the language can not express multi-source, more semantic, multiscale, and complicated spatial data and can not achieve the query, integration and location of spatial data. GML, which is worked out on the basis of XML by international Open Geospatial Consortium, is a language used to describe spatial data and is established on the basis of Public Geographic Model, at the mean while, it, owing to internal transport and accessibility of GML, is of great significance to the sharing of geographic spatial data. However, spatial data, which is stored by means of geodatabase or data files, causes spatial data not to achieve real resource-sharing. Therefore, this dissertation, which is based on the in-depth study of geodatabase and Geography Markup Language, makes use of the binding technology of Java and XML realize to convert spatial data to GML document.(3) We proposed and designed Web map service model and realize the key models. This dissertation, at first, makes further research and analysis to OpenLayers, which is a map framework, and achieves the TilesMap technology on that basis. After that, We give a profound consideration to map cache technology. At last, we apply the Web map service model into modern digital community successfully.更多还原