Wikidata does not have any official ontologies, however the DBpedia project has created an ontology that covered place types. The table below used the DBpedia place ontology as a starting point, and is provided as a cross-reference to the relevant OSM tags.
The Wikidata place types listed in the table below can be used in conjunction with the Wikidata Query Service to retrieve instances of those place types from the Wikidata knowledgebase.
SELECT ?item ?lat ?lon
WHERE {
?item wdt:P31*/wdt:P279*wd:Q9430; wdt:P625 ?pt.
?item p:P625?loc.
?loc psv:P625?cnode.
?cnode wikibase:geoLatitude?lat.
?cnode wikibase:geoLongitude?lon.
}
An example json return for all instances of the Wikidata item "Q9430" (Ocean) can be seen at json
NOTE the OSM tags listed are those listed in the wikidata entries, and not all the possible matches for tags within OSM.
The Wikidata improvements to Nominatim can be further enhanced by:
- continuing to add new Wikidata links to OSM objects
- increasing the number of place types accounted for in the wikipedia_articles table
- working to use place types in the wikipedia_article matching process