Slides for Kerameikos.org and the Linked Art showcase at the Victoria & Albert Museum

Next week I will be heading to Oxford for the AHRC-funded face-to-face meeting for the Linked Art scientific committee. On Tuesday is a showcase workshop at the Victoria & Albert Museum that I sadly cannot attend, but I have put together a small slideshow with notes that I think Sami Norling from the Indianapolis Museum of Art at Newfields will read (since the Linked Art JSON-LD harvester is built around test examples from the IMA). The slides are as follows:

 

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 Gazetteerof 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.

 

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.

 

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.

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.

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.

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.

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.

First German translations added to Kerameikos

The first German translations for Kerameikos.org-published Greek pottery shapes have been published online through Kerameikos' spreadsheet import mechanism. These translations include preferred labels, alternative labels, and definitions. They were provided by Nicole High-Steskal and Laura Rembart of the Austrian Archaeological Institute. Nicole has recently moved to the Digital Lab at the Image Science department at the Danube University Krems.

DOIs for these intellectual contributions to Kerameikos.org will be created for Nicole and Laura soon.

Aligning Kerameikos more directly with Linked Art

I have been steadily developing a prototype data harvester that will perform some minor alterations to Linked Art-compliant JSON-LD in the XForms backend in order to ingest museum data into Kerameikos.org's SPARQL endpoint. I will write more details later as I complete the prototype (it will be ready for demonstration in time for the Linked Art Face to Face meeting in Oxford in two weeks), but in the course of testing the harvest process on some example JSON-LD from the Indianapolis Museum of Art, I have transitioned the Kerameikos RDF data model to adhere more strictly to the Linked Art profile.

The original data model developed for Kerameikos was a simplified CIDOC-CRM based on examples from the British Museum and feedback from Ontotext's Vladimir Alexiev. The focus of the model was to capture properties directly linked to various categories of Kerameikos SKOS concepts (artists, production places, techniques, shapes, etc.), with only a handful of literals encoded more simply in dcterms than the the CRM approach (e.g, for title and accession number, dcterms:title and dcterms:identifier). Several properties and classes were created in a Kerameikos.org ontology in order to fill gaps in CRM modeling and/or more accurately represent the way in which pottery scholars organize knowledge within their own discipline as opposed to a more general art museum approach. These Kerameikos properties still exist within the hybrid Linked Art data model since a category like "Shape" is more easily and logically connected via a kon:hasShape property rather than creating types of types.

Paging through Indianapolis Museum of Art photos for a vase of Hermonax.

A summary of changes is a follows:

• Title and Accession number are linked via crm:P1_is_identified_by, which have different classes and types defined by AAT URIs.
• Static images and IIIF services are Visual Items linked via crm:P138i_has_representation, replacing foaf:depiction. More than one can be accommodated. Thumbnails (foaf:thumbnail) have been tabled until Linked Art develops a stable model for representing more than one size for the same photograph.
• 3D model links are also crm:P138i_has_representation. The Visual Items are given relevant dcterms:formats.
• The IIIF manifest is linked as an Information Object with the crm:P138i_has_representation property.
• The IIIF/3D model updates have resulting in deprecation of the old Europeana Data Model specification.
• Kerameikos implements the model for dimensions, which are converted to metric in the harvester 

These model changes have necessitated writing a simple XSLT identity transformation to generate new static RDF/XML files our test vase data as well as updates to the underlying SPARQL queries for objects related to SKOS Concepts and the Pelagios data export. Since the new model can accommodate multiple images per vase (with the dcterms:format/dcterms:conformsTo for the Visual Item being necessary to generate UI distinctions for static images vs. IIIF vs. 3D model display in Sketchfab or 3DHop), I switched the queries from SELECT to CONSTRUCT and updated the XSLT to serialize the results to HTML or RDF (for Pelagios) from an RDF/XML model instead of the SPARQL XML response.

CONSTRUCT {?object a crm:E22_Man-Made_Object ;
            dcterms:title ?title ;
            dcterms:identifier ?id ;
            dcterms:publisher ?keeper; 
            crm:P138i_has_representation ?representation ;
            crm:P129i_is_subject_of ?manifest .
          ?representation dcterms:format ?format ;
            dcterms:conformsTo ?conformsTo} WHERE {
%STATEMENTS%
?object crm:P1_is_identified_by ?id1 ;
    crm:P1_is_identified_by ?id2 .
?id1 a crm:E33_E41_Linguistic_Appellation ;
    crm:P190_has_symbolic_content ?title .
?id2 a crm:E42_Identifier ;
    crm:P190_has_symbolic_content ?id .
OPTIONAL {?object crm:P50_has_current_keeper/skos:prefLabel ?keeper .
    FILTER (langMatches(lang(?keeper), "en"))} 
OPTIONAL {?object crm:P138i_has_representation ?representation
    OPTIONAL {?representation dcterms:format ?format}
    OPTIONAL {?representation dcterms:conformsTo ?conformsTo}}
OPTIONAL {?object crm:P129i_is_subject_of ?manifest}
}

Kerameikos is now a functioning Pelagios Network hub

As per the specifications we outlined in our National Endowment for the Humanities Digital Humanities Advancement Grant application, Kerameikos.org is now a functioning data hub for the Pelagios Network. Like Nomisma.org, objects aggregated into the Kerameikos SPARQL endpoint can be outputted into the Pelagios Open Annotated-based RDF model with a SPARQL query response that is piped through XSLT into RDF/XML. The export model includes some references to IIIF services for a few vases from Harvard Art Museums (as a proof of concept).

While there are over 300 vases in the Kerameikos SPARQL endpoint at the moment, the export includes just under 200 objects that are currently connected to Pleiades URIs through skos:exactMatch with Kerameikos place URIs. In our initial prototype from 2014, a few dozen vases from the Getty Museum were encoded in Getty TGN URIs and British Museum vases were linked to the BM's internal place thesaurus. Using Kerameikos as a bridge between vocabulary systems, the SPARQL query for the Pelagios output includes all vases linked directly to a Kerameikos URI as a production place (?object crm:P108i_was_produced_by/crm:P7_took_place_at ?place) as well as vases linked to any URI that is a skos:exactMatch for a Kerameikos URI. The Pleiades URI is then extracted into the ?match variable.

Coverage of Kerameikos partners in Peripleo.

?object crm:P108i_was_produced_by/crm:P7_took_place_at ?place .
{?place skos:exactMatch ?match FILTER strStarts(str(?match), "https://pleiades")}
UNION {?place^skos:exactMatch ?kid .
  ?kid skos:inScheme kid: ;
       skos:exactMatch ?match FILTER strStarts(str(?match), "https://pleiades")}

The partners whose vases have been integrated into Peripleo include the British Museum, Getty Museum, Ure Museum at the University of Reading, Fralin Museum at the University of Virginia, Indianapolis Museum of Art at Newfields, and the Harvard Art Museums. We expect the list of contributors to grow as more museums and archaeological datasets become part of the Kerameikos Linked Open Data cloud as as we begin to expand our geographic coverage (which is extremely limited at the moment, with URIs created for only a small handful of places).

Indianapolis Museum of Art vases integrated into Kerameikos

Approximately a dozen Greek vases from the Indianapolis Museum of Art at Newfields have been integrated into the ceramics Linked Open Data cloud in the Kerameikos.org SPARQL endpoint. The list of vases can be seen at the Kerameikos URI for Newfields (http://kerameikos.org/id/ima_newfields), as well as on the concept pages related to these vases.

Newfields is a partner of the Linked Art community that is working to define standard CIDOC-CRM / JSON-LD models and APIs for cultural heritage data exchange. The prototype JSON-LD data export for these vases will serve as a test-case for building a Linked Art harvester to transform vase data into a more simplified graph of CIDOC-CRM fully integrated with Kerameikos URIs (by automatically reconciling Getty vocabularies upon harvest). This software development work, facilitated by our grant from the National Endowment for the Humanities, will open the door to harvesting data from a growing number of museums as they begin to implement Linked Art APIs.

The data for this initial import were provided by Sami Norling at Newfields in the form of CSV, which was reconciled with OpenRefine to Kerameikos.org URIs. A wrote a simple script to transform this URI-embedded CSV into a simplified CIDOC-CRM RDF model that includes only the essential information for basic query and visualization within the Kerameikos platform..