| Spatial
relations play an important role in query languages of SDBMs. They are
usually classified into topological relations, cardinal directions and
distances. Among these relations, topological relations have been
specially studied and formalized in query languages. Toplogical relations are invariant under elastic transformations, such as, translation, rotation and scaling. They refers to relations between spatial objects that reflect a connectivity property. Examples of topological relations are disjoint, overlap, inside and contain. A widely used formalization of topological relations is the 9-Intersection model (Egenhofer and Franzosa 1991). In this model, topological relations are derived from the set intersection of objects' interiors (a°), objects' boundaries (δa) and objects' exterior (a-). Topological relations for simple regions:  |
Última modificación: Thursday, 24 de November de 2005, 14:41