基于SVG的空间信息描述与可视化表达

The Spatial Information Description and Visualization Based on SVG

SVG是移动互联时代随时随地获得各种丰富图形信息的有效方法,在LBS系统中,它也可以是空间信息描述与表达的有效方法。本文首先研究了空间信息与SVG标记间的映射关系,其次研究了SVG表示空间信息的生成方法,然后基于SVG的树状结构,在分析XML各种解析模式与图形元素渲染过程的基础上,提出了采用"pull"模式和DVR视图相结合的SVG解析与渲染方法,最后以复杂地物和考虑层控制策略时多层数据的SVG渲染结果,说明 收稿日期:2003 08 11;修回日期:2004 09 09基金项目:国家高科技研究发展计划资助项目(2001AA136031);国家自然科学基金资助项目(40271093,40401051);武汉市科技计划资助项目(20021002044)作者简介:李清泉(1965 ),男,安徽天长人,博士,教授,博导。主要从事空间数据模型、空间信息服务、激光测量技术、无线通信等方面的理论与技术研究。95第1期 李清泉等:基于SVG的空间信息描述与可视化表达采用SVG这种开放的图形格式描述与表达空间信息是可行的,并且在空间信息移动服务中可以解决客户端多样性问题,有利于空间信息服务的普及与推广。

With the supporting LBS, the spatial information and services are becoming accessible from a wide range of mobile devices, from cellular phones, PDA, and in-car computers to palmtop computers and other small mobile devices. Many wireless and mobile devices are characterized by small display screens, limited processing speed, low bandwidth connection, small memory and so on, and these considerations also need to be taken into account when building LBS system. It is not a graceful method to prepare for different data according with different device. On the one hand, the kind of Multi-client devices is rich and colorful. On the other hand, the same data must be stored in different versions in server sides. XML technologies separate content from presentation, which will solve the problem along with the multi-client devices. SVG as a XML dialect in Internet graphics is an effective method that can get abundant figures at any moment in mobile interconnected era, and is also an effective method that can descript and visualize the spatial information in LBS. In this paper, we firstly researched the map relationship between spatial information and tag of SVG. Secondly, the SVG building method from spatial information was introduced. Then based on analyzing the model of XML parse and the process of geometry render, the 'pull' parse model and DVR view combined to a SVG parse and rendering method is proposed. Finally, based on the SVG rendering result of the complex feature and multi-layer data reference to the policy of layer control, it is feasible to apply SVG to descript and visualize spatial information. SVG can settle the problem of many client devices in LBS and make for the popularization and spread of spatial information.