Geographic Databases

Abstract

AbstractGeographic databases are concerned with the representation of objects and phenomena occurring on the surface of the earth. Geographic objects include countries, cities, roads, rivers, mountains, train and telephone line networks, weather patterns, etc. The geographic database representations take the form of various types of maps or different kinds of graphs that express some of the relationships among the geographic objects.Spatial databases include geographic databases but are more general because they can be concerned with not strictly geographic phenomena. For example, spatial databases can store information about the astronomical information such as the galaxies and the stars of the universe or the layout of an integrated circuit. Despite this slight distinction, the terms geographic databases and spatial databases are often used interchangably. In addition, the term geographic information system (GISs) became popular instead of geographic database systems. Since our goal is to emphasize data models instead of systems, this chapter will talk about geographic databases and geographic data models. Extreme points data models is the class of geographic data models that represent geographic objects via simple geometric shapes, such as, rectangles, lines, or polygons. Extreme point data models place a special emphasis on the endpoints of these geometric shapes. This chapter presents three extreme point data models. In particular, Section 6.1 describes the rectangles data model, which deals exclusively with rectangles, Section 6.2 introduces the vector data model, which deals with polylines and polygons, and Section 6.3 presents Worboys’ data model, which deals with triangles.KeywordsData ModelQuery LanguageSpatial DatabaseGeographic Information SystemConstraint RelationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.