虚拟GIS数据模型的设计及其主动式面向对象数据库系统的实现

本文首先在分析地学虚拟环境和虚拟地理信息系统的同时 ,指出当前虚拟地理信息系统在数据模型上的不足 ;然后具体介绍了我们设计的虚拟地理信息系统数据模型 ,在该数据模型中通过引入结构对象 ,支持地理数据在空间数据库中的管理和在地学虚拟环境中表达 ;同时介绍了该数据模型基于主动式面向对象数据库的实现 ,并在其支持下的地理对象中引入了对象事件属性 ;最后文中给出系统应用示例图。

Data Model of Virtual Reality GIS and Its Implementation Based-on Active Object-Oriented Database System

With the development of technologies of the computer graphics and computer-human interface, a new kind of Geographical Information System, Virtual GIS(VGIS or VRGIS), which is based on the traditional multi-dimensional Geographical Information System, is emerging. VRGIS extends the usage of GIS, at the same time, brings new problems for the design of the GIS. The data model always is important technology for any kind of GIS, same as to VRGIS. After discussing current researches of data model for VRGIS, the deficiency of the data model of current VRGIS is obvious. In the paper, a new data model for VRGIS is introduced in detail, in which the hierarchical structure objects are introduced in order to support the geographic data to be managed effectively by spatial database and to be displayed in the GVE. Of course, the new data model is complex, and is hard to implement in common commercial relational database. In the paper, the data model is implemented by a active object-oriented database system, moreover, the event attributes were designed as a part of the geographic objects in the data model with the help of the database system. At last, two application figures of the VRGIS system are illustrated.