Filling A Niche

There has never a widely adopted RDF vocabulary for representing geographic shapes. Four years ago the W3C came up with a Basic Geo Vocabulary which was restricted to representing points via their latitude and longitude, but gave no specification on how to represent lines and polygon features.

The W3C Geospatial Incubator Group has just published as their final report a pair of documents on Geospatial Vocabularies and Geospatial Ontologies. In so doing they have come up with a GeoOWL ontology that includes classes for points, lines, polygons, and boxes. It is based largely on the GeoRSS specification for encoding geographical information in RSS feeds. The ontology does not have a model for spatial relationships, e.g. being able to say a feature is contained within another. Nevertheless, being able to associate geographic shapes with any other entity solves many of the semantic modelling problems associated with biodiversity data.

Naming The World

Last winter I gave a talk about gazetteers to a geography seminar here. I mentioned some of the important online gazetteer resources (e.g. the Alexandria Digital Library gazetteer or the Getty Thesaurus of Geographic Names), but somehow hadn’t yet run across perhaps the most interesting web-oriented gazetteer project to date, GeoNames.

The GeoNames gazetteer project has been around for a couple of years and currently contains more than eight million geographic names representing 6.4 million unique geographic entities. The project started off by assembling some of the major public domain gazetteer resources such as the USGS Geographic Names Information System for place names in the US and the National Geospatial-Intelligence Agency database for non-US names, but has expanded its content to include many other sources as well. GeoNames provides an elaborate RESTful API to its data and in a wiki-like fashion allows people to enter or correct placenames on their own.

A year ago, Bernard Vatant set about the task of integrating GeoNames into the Semantic Web, and with a little help from Harry Chen put together an ontology for placenames in GeoNames together with a URI scheme for the placenames backed by Semantic Web-friendly content negotiation.

From the point of view of somebody who wants to refer to placenames in a Semantic Web document, this set of URIs is a great resource. As a case in point, we are interested in providing species lists in RDF for various geographic regions. Often such species lists refer to named regions rather than geographic coordinates (for instance “Yolo County, California”). It is now straightforward to come up with a URI for such a region — Yolo County is represented by http://sws.geonames.org/5410882/. Even better, the fact that users can add their own placenames allows the creation of good URIs for locations with species lists that aren’t yet in GeoNames.

GeoNames is getting ever more comprehensive, though. It’s fun to see that the building where I’m writing this now, Wickson Hall, already has a GeoNames URI.