地理信息系统的数据模型与系统结构

GIS Data Model and Its Architecture

数据模型是描述数据内容及其相互关系的工具，它是数据库设计的核心问题之一。空间数据相对于一般事务性数据具有数据量大和更加复杂的特点，因此，地理信息系统（ＧＩＳ）中空间数据模型的研究显得尤为重要。商业化的ＧＩＳ一般采用关系数据模型，而关系数据模型缺乏表达空间实体及其相互关系的能力，因此形成了图形库与属性库相分离的ＧＩＳ系统结构。这种结构不便于空间实体的整体管理。为解决这一问题，人们探索了扩展的关系模型和面向对象的数据模型。本文介绍了这三种ＧＩＳ数据模型及其与之对应的三种系统结构，分析了这些模型与系统结构的优越性和不足之处，并揭示了数据模型与系统结构之间的内在关系。

Data model is a representation of data and its relation. It is consi-dered very important in database design. In constrast to alphanumerical data, spati- al data is characterised by its large magnitude and complexity.Therefore,it is ofsignificance to do research on spatial data model.Most commericial GISes are basedon relational data model.However,its drawbacks on representing spatial entitiesand their interrelations have led to the separation of graphic database and attributedatabase. In order to overcome this problem,extended relational data model andobject-oriented data model are explored.This paper introduces these three data mo-dels and their corresponding GIS architecture,analyses their pros and cons, and pre- sents the relation between spatial data model and GIS architecture.