分布异构空间数据协同编辑关键技术研究

分布式环境下空间数据库的异构、多源、多平台特性,使不同系统之间难以实现协同处理。为实现分布异构空间数据的协同编辑,在研究网络要素服务(Web Feature Service,WFS)规范的基础上,对WFS规范中的锁定、编辑操作进行了改进,同时将发布订阅机制引入到基于WFS的网络空间数据编辑处理中,使其能够适应协同编辑的需求,并以此为基础提出了基于WFS的一致性控制机制、编辑机制和发布订阅机制,最后建立了相应的原型系统以验证其有效性。     

Constructing Geo-information Sharing Architecture

IntroductionAlong with the development of computer andInternet technology , GIS applications are be-coming broad increasingly ,geo-information sha-ring are of increasingi mportance ,and geo-infor-mationinteroperabilityis the trend in the futureGIS applica…     

基于本体的网络地理空间数据集成

 随着地理数据深度、广度和复杂度的不断增加,如何集成这些在结构、语法及语义上高度异质性的需求越来越迫切。尽管XML在一定程度上解决了结构异质性问题,OGC标准规范解决了语法异质性问题,但语义异质性问题仍然成为分布式环境下地理空间数据集成与互操作的最大障碍。本文提出了一种基于本体的网络地理空间数据集成方法:以本体思想对数据进行语义组织;结合OGC网络服务标准规范对数据进行服务语义发布;利用支持双向映射的混合本体模式来解决全局本体与各应用本体之间的冲突,实现数据的语义集成。通过海洋海岸带土地利用数据集成试验表明,本文方法不仅能够克服数据间语义异质性问题,并在很大程度上屏蔽了数据底层集成的复杂环节,使得数据集成过程简单、高效。     

Developing a Geographic Visualization Tool to Support Earth Science Learning

This paper reports on the development and assessment of the EarthSystemsVisualizer (ESV), a geovisualization tool designed to facilitate learning about global weather. Our goals in designing ESV were to evaluate two exploratory spatial data analysis (ESDA) techniques, temporal brushing and temporal focusing,and to determine whether interactive geovisualization tools influence problem solving strategies, approaches to learning, and students' ability to generate hypotheses about earth-science processes. Focus group sessions were conducted with both expert and novice users to assess an initial design for the ESV interface prior to conducting a task-based assessment of ESV use. Changes were implemented in response to the focus group results, including the redesign of a temporal legend and improved speed and direction controls. Our task-based assessment considered student reactions to components of ESV, especially whether they could use it to answer questions about global-scale weather processes, and whether the system (particularly its focusing and brushing tools) had an impact on the hypotheses generated about relationships among weather variables. The assessment revealed that focusing and brushing had little impact on students' ability to answer questions about weather processes, and that performance suffered for students who were confused by the focusing and brushing tools. In fact, students who understood the tools performed the best, but students without the tools performed better than those who had the tools but were unsure how to use them. We also concluded that the level of the visualization system must be well matched to the knowledge users have about the application domain: students who already possessed an advanced understanding of meteorology or climatology benefited less and were more critical of the system than students with an intermediate or a novice level of understanding.     

基于GeoServer的移动GIS旅游系统设计与实现

在对移动GIS技术和框架分析的基础上,选取GeoServer地理信息发布平台,进行移动GIS旅游系统功能设计;采用OGC提出的空间数据互操作规范WMS、WFS实现地理信息数据交换;以七台河旅游数据作为专题数据,实现移动端旅游景点查询与语音导游系统。     

A proposed framework for feature‐level geospatial data sharing: a case study for transportation network data

Current data sharing in the Internet environment is supported using metadata at the file level. This approach has three fundamental shortcomings. First, sharing data from different sources with different semantics, data models, and acquisition methods usually requires data conversion and/or integration like data conflation. This can be tedious and error‐prone. Second, data updated from one source cannot be automatically propagated to other related data or applications. Finally, data sharing at the file level makes it difficult to provide feature‐level data for searching, accessing, and exchanging in real time over the Internet. This paper addresses these three issues by proposing a standards‐based framework for sharing geospatial data in the transportation application domain. The proposed framework uses a standard data model—geospatial data model proposed by the Geospatial One‐Stop initiative to harmonize the semantics and data models without the use of data integration methods. It uses Geography Markup Language (GML) for geospatial data coding and feature relationship, which provides a basis to propagate the data update from one source to related other sources and applications, and to search and extract data at the feature level. The framework uses the Web Feature Service (WFS) to search, access and extract data at the feature level from distributed sources. Finally, the Scalable Vector Graphics (SVG) standard was used for data display on the Web browser. Two transportation network datasets are used in the prototype case study to implement the proposed framework. The prototype allows the user to access and extract data at the feature level on the Web from distributed sources without downloading the full data file. It shows that the proposed standards‐based feature‐level data‐sharing system is capable of sharing data without data conflation, accessing, and exchanging data in real time at the feature level. The prototype also shows that changes in one database can be automatically reflected or propagated in another related database without data downloading.     

利用本体的WFS要素语义检索研究

为了实现基于多源WFS服务要素层次的语义检索,提出了一个要素本体的五元模型。在此框架下,研究了要素本体的自动构建方法,形式化定义了要素的空间关系,并扩展了逻辑关系以及空间关系的推理规则来实现要素层次的联合推理检索,并给出了联合规则推理的要素语义检索算法。实例证明,本文方法对多源WFS的语义查询具有实际的可行性,为多源WFS服务要素的语义检索提供了一个新的方法。     

Automatic search of geospatial features for disaster and emergency management

Although the fast development of OGC (Open Geospatial Consortium) WFS (Web Feature Service) technologies has undoubtedly improved the sharing and synchronization of feature-level geospatial information across diverse resources, literature shows that there are still apparent limitations in the current implementation of OGC WFSs. Currently, the implementation of OGC WFSs only emphasizes syntactic data interoperability via standard interfaces and cannot resolve semantic heterogeneity problems in geospatial data sharing. To help emergency responders and disaster managers find new ways of efficiently searching for needed geospatial information at the feature level, this paper aims to propose a framework for automatic search of geospatial features using Geospatial Semantic Web technologies and natural language interfaces. We focus on two major tasks: (1) intelligent geospatial feature retrieval using Geospatial Semantic Web technologies; (2) a natural language interface to a geospatial knowledge base and web feature services over the Semantic Web. Based on the proposed framework we implemented a prototype. Results show that it is practical to directly discover desirable geospatial features from multiple semantically heterogeneous sources using Geospatial Semantic Web technologies and natural language interfaces.     

基于GML和WFS及SVG的WebGIS实现框架

异构数据的交互性与客户端显示地图的图形质量问题,是目前W ebG IS技术实现方面比较突出的两个方面,作者在此推荐一种完全基于国际标准的W ebG IS实现框架,它能够很好解决上述W ebG IS技术实现方面的焦点问题。