Linked Open Greek Pottery: Kerameikos.org and Linked Art

posted on 16.01.2020 by Gruber, Ethan

This is a brief slideshow intended to be delivered (by Sami Norling?) in my absence from the Linked Art: Networking Digital Collections and Scholarship event at the Victoria & Albert Museum, 1 October 2019.

[slide 1]

Kerameikos.org is an international project that seeks to define the intellectual concepts of ceramics studies following the principles of Linked Open Data. This phase of the project is funded by the US National Endowment for the Humanities and is focused primarily on creating URIs for Archaic and Classical Greek pottery concepts, which includes authoring definitions for shapes, artists, techniques, production places, etc. and linking them to equivalent entries in other LOD thesauri, such as the Getty and British Museum vocabularies and the Pleiades Gazetteer of Ancient Places. We are also aggregating vase data from partner collections as a proof of concept to facilitate new types of query and visualization. The emerging Linked Art community plays a significant role in this process.

[slide 2]

The Indianapolis Museum of Art at Newfields has a small collection of Greek vases that have served as a test case for building a harvester that integrates Linked Art-compliant JSON-LD into Kerameikos' Linked Open Data ecosystem. This vase pictured here in the IMA, represented by a URI, is a particular shape called a stamnos. It was painted by Hermonax, an Athenian artist, in the Red-figure technique in roughly the mid-5th century B.C.

[slide 3]

In a test of JSON-LD provided by Sami Norling at the IMA, some minor modifications were made to fill in any gaps in cataloging with the relevant Getty Art & Architecture Thesaurus, Union List of Artist Names, and Thesaurus of Geographic Names identifiers. These URIs have equivalencies in Kerameikos.org and other systems.

[slide 4]

The harvesting workflow parses the Linked Art JSON-LD and distills it into the most basic network graph, represented here as RDF/XML conforming to the the underlying Linked Art profile in the CIDOC CRM ontology. The human-readable labels from the JSON, which may be useful to developers working directly with that format of data, are removed, since the preferred labels in English and other languages are already inherent to Kerameikos.org's own thesaurus data model.

[slide 5]

After entering basic metadata about a dataset (in this case, the IMA's collection of Greek vases) and a link to the JSON-LD file on a web server (which will one day be a URL for an API response), the harvester will extract the JSON and process each human-made object into RDF/XML, replacing Getty URIs with Kerameikos ones, when applicable. After this completes, the RDF is published to the Kerameikos.org SPARQL endpoint. SPARQL is a query language for linked data, and the underlying triple database is the backbone of aggregation in this project, as well as Nomisma.org, a similar linked data project for numismatics.

[slide 6]

After the workflow completes, the vases will immediately become available in the pages associated with concepts connected to the IMA's vases, for example kerameikos.org/id/stamnos or kerameikos.org/id/hermonax. This user interface can accommodate multiple jpeg images per vase, as well as IIIF services and several types of 3D models rendered in the 3D Hop library or the Sketchfab viewer.

[slide 7]

By means of the relationship between the Getty Thesaurus of Geographic Names, Kerameikos.org place identifiers, and the Pleiades Gazetteer of Ancient Places, it is possible to build a transformation process that converts Linked Art RDF into a different RDF data model required by the Pelagios Network. Kerameikos.org is now a data hub for Pelagios, and currently about 200 Greek vases from 6 partners are available in the Peripleo explorer. This number will grow into the thousands in the coming months and years as the full range of British Museum, Getty, and archaeological pottery are integrated into Kerameikos.

In conclusion, as the Linked Art standard begins to proliferate throughout the museum community, harvesting will be greatly simplified by having one set of APIs and models that can be applied broadly across many museum or archaeological databases, rather than relying on intermediate processes of OpenRefine data cleaning and spreadsheet-to-RDF transformation with one-off programming scripts.