Object‐oriented modeling of geographic data

Two levels of data abstraction, namely conceptual and logical, are essential in the process of designing an object‐oriented geographic database. The aim of the present article is to establish a consistent framework for this bilevel design. At the conceptual level, we develop an object‐oriented model useful for organizing the designer's knowledge about a geographic application in terms of the basic concepts of the object‐oriented paradigm. Both conceptual abstraction primitives (namely, classification, generalization, and aggregation) and a spatial abstraction primitive (namely, location) are discussed. The dynamic part of the model is due to the methods associated with objects. At the logical level, we propose an object‐oriented structure of classes and instances, which is uniform with the conceptual model and, therefore, facilitates the conceptual logical mapping. On the whole, the model‐based approach adopted in this article offers object orientation, conceptual abstraction, and system extendibility. © 1994 John Wiley & Sons, Inc.