基于ORDB的地理空间对象模型M-L-E(S,A)改进研究

针对地理数据中空间对象概念模型,尝试利用对象-关系数据库(ORDB)的一些优势,对已有的地理数据中空间对象的M-L-E(S,A)分层模型进行了改进,实体之间可以通过类、继承等方式产生和关联,地图和图层之间、图层和实体之间采用引用方式实现连接,不再存在从属关系,实现了更大程度的共享,可以更好地体现ORDB相对于OODB或RDB对地理空间数据的表达。同时提出了该模型的形式化表达,并对空间实体、图层和地图各层次分别进行了分析讨论,提出基于ORDB的支持方式和特点,并设想了地图尺度转化从图层到实体向下层追溯的过程。

Study of Modified Model M-L-E(S,A) of Geographical Spatial Object Based on ORDB

This paper focuses on using conceptual model of spatial object for analyzing geographical data.The author tries to improve the existing hierarchy model of M-L-E(S,A) by taking into account of the advantages of object-relational database(ORDB).Entities in the modified model are created and connected by using class or inheritance methods.Connecting by references,there is no affiliation between layers in a map or entities.Therefore it is a better way of sharing and expressing spatial objects by employing ORDB rather than object-oriented database (OODB) or relational database(RDB).This paper also addresses the formula expression of the model and analysis of spatial entities,layers and maps based on ORDB.At the end,based on the method and characteristics of ORDB,the process of tracing map scales back to layers and entities are discussed.