【摘要】 数字地球是当前网络G IS领域的研究与开发热点之一,其中,大量的空间数据在空间数据库中的组织和存储,以及在网络上的传输是数字地球系统中的两个重要技术。本文通过"数字南海"的开发实践,从国家信息安全角度出发探讨了自主设计与研发空间关系数据库模型和网络传输协议的若干技术方法。提出了以面向对象的ORM源模型设计空间数据库概念模型,以擅长语义表达的IDEF1X模型设计空间数据库逻辑模型和以关系数据库实现空间数据库存储模型的技术方案。并运用异步非阻塞套接字和多线程等技术在TCP/IP网络传输协议上,设计并实现了空间数据应用传输协议,使得空间数据在数字地球的客户端三维显示系统与服务器端的空间数据服务器系统之间能够高效安全地传输,实现Google Earth类似的操作功能,包括空间数据的流式传输和渐进式传输等,适应了数字地球的要求,并保证了空间数据的安全性,可为我国数字地球系统的自主开发与研制提供参考和借鉴。更多还原

【Abstract】 Digital Earth now is becoming one of the leading technologies in the Internet GIS research and development.In this area,there are commonly two of the key techniques that a Digital Earth software system′s development process should deal with: one is the great amount of spatial data should be properly organized and stored in spatial databases,and the other is the spatial data should be effectively transported on networks such as Internet and/or Intranet.By the implementation of the Digital South China Sea(DSCS) system,this paper discusses several technical methods that can mainly be used for independently design and development of geo-relational database models and transport protocols on account of concerning the nation’s information security issues.The resulting modeling solutions for the DSCS are: Firstly,the object-oriented ORM source model is adopted as a new spatial database data conceptual modeling technique.Secondly,the logical model of the spatial database is built by using the IDEF1X model which is more effective in semantic description.And thirdly,the storage model of the spatial database is based on relational database.Besides,the spatial data transport protocol is designed and implemented using the asynchronous unblock socket method together with the multithreading method in C++ programming,and directly on the basis of the TCP/IP protocol.It is proved by testing the DSCS system on networks that these technologies can make the spatial data efficiently and safely exchange between the three-dimensional rendering client system and the spatial data server system that are a necessity for a Digital Earth.The DSCS also supports most of the functions and manipulations which are similar to the Google Earth,e.g.the database storage of spatial data such as points,curves,polygons and images,data streaming and progressive transportation etc.For the fully possessed proprietary intellectual property right to the database model and the transport protocol,the DSCS can improve the development of China’s national Digital Earth system and provide more safety guarantee to the important spatial data of the nation when transporting on the Internet.更多还原