Wednesday, April 7, 2021

Dutch National Numismatic Collection added to CRRO

The Dutch Nationale Numismatische Collectie, published by De Nederlandsche Bank, is the latest collection to join the numismatic Linked Open Data cloud. Nearly 2,200 Roman Republican coins from the collection have been linked to Coinage of the Roman Republic Online (CRRO) URIs through OpenRefine, and exported directly into RDF with a template. There are now more than 52,000 Republican coins in CRRO, making it, by far, the most comprehensive research tool for this corpus of material.

A small number (about a dozen) coins have known findspots that were reconciled to URIs. Using Wikidata's SPARQL endpoint, I extracted coordinates for these places, as well as the entire geographic hierarchy up to the country level, making it possible to begin querying coin finds of the Netherlands in a systematic way. Hopefully the Portable Antiquities of the Netherlands (PAN) will eventually integrate with CRRO and Online Coins of the Roman Empire (OCRE) URIs, painting a more complete picture of the circulation of Roman coins into the Netherlands.

Distribution of DNB coins for RRC 285/2, with two finds.

In the near future, a substantial portion of the NNC-NDB's Hellenistic collection will be linked to Hellenistic Royal Coinages URIs, and then the Roman imperial collection will be integrated into OCRE following its complete digitization and cataloging.

Friday, April 2, 2021

Getty Roman Republican coinage in CRRO

The J. Paul Getty Museum is the latest to join the Linked Open Data cloud. With special access to their development Linked Art JSON-LD API combined with their experimental SPARQL endpoint, I have been able to extract 66 coins with RRC references, with a query built around the Linked Art CIDOC-CRM profile.

I took the resulting CSV data from the endpoint and loaded it up into OpenRefine for some further cleanup, to link to the Coinage of the Roman Republic URIs for coin types, and to pull the Linked Art JSON-LD into OpenRefine in order to extract the IIIF Manifest and image service API URIs. For the first time, I experimented with OpenRefine's built in template export scheme, and put together a generally reusable template to export Nomisma-compliant RDF directly from the app (rather than authoring a one-off PHP script to transform cleaned CSV data into RDF). This saved considerable time. I threw this template into Gist, and so I can generate Nomisma RDF from any OpenRefine data. Hopefully this will open the door to other contributors cleaning their own data and providing us the RDF directly without further intervention.

A sample of the representation of RRC 422/1a

There are some 700 Roman Imperial coins with RIC references that I will eventually link to Online Coins of the Roman Empire. This task is a bit more complex, but it can be knocked out in an afternoon. The Hellenistic coins in the Getty aren't cataloged with type references, and so there's no way to integrate these until a curator identifies and links them.