Basic components of the Entity Relation model are: entities, relations, attributes, keys, and cardinality Spatial objects can be modeled by defining entities and relations between these entities and entities that describe geometric representations in a space, namely:
 Consider the following two models of entities landparcel and river.  This first model has no geometric representation, which requires a explicit modeling for each topological relation (ex., topologica, distance, and cardinal relations) or geometric attribute (ex. area, perimeter).  The second model represents explicitly the geometry of objects. Even more, more than one geometric representation are possible, and spatial relations and geometric attributes are derivable. |
Última modificación: Wednesday, 23 de November de 2005, 16:51