GIS中面向对象时空数据模型

AN OBJECT ORIENTED SPATIO TEMPORAL DATA MODEL IN GIS

由于当前的地理信息系统软件难以处理时态现象，时态数据模型已成为ＧＩＳ领域的一个研究热点。许多学者提出了多种时态数据模型。本文作者在提出了矢量栅格一体化的面向对象数据模型之后，再一次对时态问题进行了分析研究，将面向对象的数据模型扩充到时间维。有三种方法表达空间对象的历史变化。第一种是将版本信息记录在关系表上；第二种是将版本信息标记在记录上；第三种是将版本信息标记在属性上。本文采用面向对象的方法，将版本信息标记在属性上，直接表达同一个对象不同时期多个版本的属性值。它不仅节省了存贮空间，而且对空间对象的检索和历史事件的查询带来了方便。这种面向对象的时空数据模型，可以按照统一的模式和方法，同时考虑空间对象的几何、拓扑、属性甚至栅格的时态问题。本文在提出时空数据模型之后，还讨论了它的实现途径，提出了用对象标识记录对象版本的新方法。

It is difficult for current Geographic Information System(GIS) software to deal with temporal phenomenon, so 3 D and 4 D temporal data models have now been becoming an issue that is receiving attention in the GIS area. Many scholars have advanced a lots of temporal data models. After proposing the object oriented data model(OODM) based on an integrated vastervector data structure, the author of this paper further discusses the temporal phenomenon in the real world, and introduces time dimension(time D) to OODM. There are three approaches to representing the historical changes of spatial objects in a database: stamping version information on a relational tables, on records, and on attributes. The paper introduces an object oriented approach to stamping a version information on attributes, so that attribute values of an object in different periods can be described directly. It not only saves the storage space, but also is more convenient to retrieve an spatial object and quarry over a historical event. This data model represents the 3 D spatial and temporal information, and their relations including attribute data, geometric data(vector and raster), topological relations and time. It can be established using a unified model. Finally, an new approach to record version using object identification(OID) and path to realize the spatio temporal data model are proposed.