排序方式: 共有140条查询结果,搜索用时 31 毫秒
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由于GML所采用的层次模型与关系模型之间存在重大差异,传统的关系模型不适合半结构化的GML数据的存储.针对该问题,本文从本原XML数据库(NXD)的角度,对GML空间数据存储问题进行了研究.首先分析了NXD的特征及其相对于XED的优势,然后对当前主流NXD的优缺点进行分析与比较,结合GML的特点,选用eXist对GML... 相似文献
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目前GIS软件的种类繁多,数据格式极不统一,行业间GIS数据格式差异相当大,造成了重复建库、浪费资源、数据难以维护的局面。鉴于以上现状,本文提出了一种基于Web Service、GML技术的分布式异构多级空间数据转换的解决方案,旨在实现不同类型、不同存放介质GIS数据之间无损失的数据共享。提供给用户的使用程序逻辑概念清楚,操作简单,部署方便。 相似文献
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3维城市模型标准化的研究,尚未引起国内学者的注意,本文以3维城市模型为研究对象,分析了CityGML模型的概念,专题模型的构建方法,给出了构建的实例,相信对从事相关工作的同行有着重要的参考价值和借鉴意义。 相似文献
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Z.‐R. Peng 《International journal of geographical information science》2013,27(4):459-481
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. 相似文献
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Haosheng Huang Yan Li Georg Gartner 《International journal of geographical information science》2013,27(10):1561-1574
XML/GML/SVG-based approaches are promising for building Web-based geographic information systems (WebGIS). However, current XML/GML/SVG-based WebGISs are lacking in spatial analysis. Some of them are designed for web mapping only. Others adopt a server-side solution for spatial analysis, which suffers from the ‘bottleneck’ problem and results in a high network transmission load. Load-balancing spatial analysis between server side and browser side can be used to solve the above problems. This article focuses on one of the key building blocks of load-balancing spatial analysis, that is, SVG-based spatial analysis which enables spatial querying and analysis directly on SVG (on the browser side). After analyzing the workflow of spatial analysis, we identify and focus on two key issues in providing spatial analysis on SVG: SVG-based spatial information representation and SVG-based spatial extended structured query language (SSESQL). For the first issue, a theoretical foundation is set up to develop an SVG-based spatial information representation model. Some spatial operators are designed and integrated into an SSESQL to support spatial querying on SVG. Finally, we design and implement two case studies. The results of these case studies show that the proposed method is feasible and operable in supporting spatial analysis directly on SVG on the browser side. The proposed method can be easily incorporated with some existing methods (e.g., GML-based spatial analysis on the server side) to provide load-balancing spatial analysis (load balancing between server side and browser side) in XML/GML/SVG-based WebGIS. As a result, users can access high-performance spatial analysis simply via a web browser (such as Internet Explorer and Firefox). 相似文献
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基于Web服务和GML的空间数据发布 总被引:4,自引:0,他引:4
针对当前信息共享存在的问题,提出Web服务和GML解决问题的思路,并讨论在基于Web服务和GML的空间数据发布中采用的关键技术。 相似文献