ABSTRACT
The fundamental database and spatial concepts introduced in the previous two chapters provide a necessary computational and geometric basis for storing and manipulating geospatial information within a computer. However, GISs do more than simply store and process geometries. GISs and geospatial information encapsulate high-level models of the geographic world around us. We begin this chapter with some issues relating to what it is that we wish to model (section 4.1). Section 4.2 goes on to define exactly what is meant by a “model,” and examines the modeling process. We then explore in detail the two high-level spatial models that have become characteristic of GIS: the field model (section 4.3) and the object model (section 4.4). The effects of adopting the field or object model can have far reaching implications for spatial data structures and implementations, in addition to how geospatial data should be understood.
