A database in which geographic information is store by x-y coordinates of single points or points which identify the boundaries of lines (or polylines, which sometimes represent the boundaries of polygons). Different attributes characterize the objects stored in these databases. In general the storing structure consists of “classes” of objects, each of them implemented by a layer. Often a geographic databases include raster, topological vector, image processing, and graphics production functionality.
Published in Chapter:
Geographic Visual Query Languages and Ambiguities Treatment
Arianna D’Ulizia (Consiglio Nazionale delle Ricerche, IRPPS, Italy), Fernando Ferri (Consiglio Nazionale delle Ricerche, IRPPS, Italy), and Patrizia Grifoni (Consiglio Nazionale delle Ricerche, IRPPS, Italy)
Copyright: © 2009
|Pages: 9
DOI: 10.4018/978-1-59140-995-3.ch042
Abstract
The main issues of spatial databases and Geographic Information System (GIS), concern the representation, the management and the manipulation of a large and complex number of spatial objects and spatial relationships. In these systems many concepts are spatial and, therefore they are intrinsically related with a visual representation, which makes also easier to formulate queries by non-expert users. The main problems in visual query languages for spatial databases concern imprecision, spatial integrity and ambiguities in query formulation. Our concern in this chapter is with the ambiguity of visual geographical queries. In particular, a review of existing visual query languages for spatial databases and their classification on the grounds of the methodology adopted to resolve the ambiguity problem are provided.