Geographic export in Nomisma.org finally migrated from Pelagios RDF to Linked Places GeoJSON-LD

At long last, the Nomisma.org geographic export from in the nearly ten year old Pelagios RDF/XML model has been migrated into Linked Places GeoJSON-LD. The query of places from Nomisma includes all mints and regions that have a spatial extent. These places are predominately mints, as only a few regions have explicit polygon spatial boundaries. As such, the Linked Places export does not include the full geographic hierarchy between mints and regions (yet), although it may be possible to generate a bounding box of a region formed by the extent of child mint locations. The new download URL is http://nomisma.org/linked-places.json.

Another requirement of a Linked Places place is a "when" property that includes a data range and optional period URIs. These are not explicit within Nomisma, although they can be derived by the link between the mint/region and a "field of numismatics" concept URI. There are about two dozen fields of numismatics in Nomisma (e.g., Roman, Byzantine, Islamic, and Greek), and I have updated these concepts to insert URIs for corresponding periods in the DAI's ChronOntology, Perio.do, and style facets defined in the Getty Art & Architecture Thesaurus. Fields of numismatics aren't precisely periods, and so they are linked with the skos:related property rather than skos:exactMatch, which is usually implemented for linking to external thesauri from Nomisma concepts.

The date range of the "when" property is required in Linked Places. It is not currently available in the JSON export, but we are going to put a broad start and end date range into the field of numismatics concepts, which we can then incorporate into the export after minor modifications to the underlying SPARQL query. Apart from this the period "name" is not populated, since we are only storing URIs for these concepts in Nomisma, and not any additional metadata we might extract from those target information systems.

Other than these temporary deficiencies, the model is fairly fleshed out. There are about 2,000 places with geographic coordinates in Nomisma.

Linked Places Geo-JSON-LD views in the GeoJSON sandbox.

 

Hopefully this export will pave the way for Nomisma.org geographic concepts to be integrated into the World Historical Gazetteer since the old Pelagios geographic aggregation system has been deprecated.