Ontology-Based Discovering of Geographic Databases Content - Advances in Cartography and GIScience - page 318

ontology. Additional knowledge taken from the database's specification,
such as selection criteria used to populate the database, is added in the
axioms used to annotate the feature classes. For example, the fact that
“only watercourses that are permanent and wider than 10 meters are
represented in the feature class ' River ' of the database”, or that “the
geometry of features ' River ' corresponds to the centreline of the modelled
watercourses” is formalised. The specification ontologies make an explicit
link between the real world entities defined in the topographic domain
ontology and their representation in the geographic databases. In order to
ensure enough homogeneity in the way to formalise the geographic
databases specifications, a common semantic model represented in OWL ,
called 'specification ontology ( SO )', and providing a unified view of the
formal geographic database specifications is also defined in (Abadie et al.
2010). This ontology reuses existing ontologies of the geographic domain
such as GeoRSS-Simple 4 . Figure 2 illustrates an example of formalization,
where the entities of the SO ontology are preceded by the prefix ' so: ',
those belonging to the ontology describing a local database are preceded
by the prefix ' lso: ', and those belonging to the topographic domain
ontology are preceded by the prefix ' topo: '. As we can see, the feature class
' Other_water_point ', which refers to a class of the database schema,
represents, in the real world, entities which are ' Loss ', ' Wash-house ',
' Watering-trough ', ' Well ' and ' Basin '. These real world entities are defined in
the topographic domain ontology. Moreover, these entities are represented
in the database as points, i.e. they have a geometry type which is a Point.
Also, we see that additional restrictions are defined on some entity classes:
only basins that are longer than 10 meters are captured in the database.
The specification ontologies and the topographic domain ontology are the
heart of our system. The former constitute the interface between the
databases and the system and the latter constitutes the interface between
the user and our system.
4 http://mapbureau.com/neogeo/neogeo.owl