Tag Archives: CIDOC CRM

GSTAR: investigation of methods for working with geosemantic data, integrating geospatial data with semantic data

Archaeogeomancy: Digital Heritage Specialists - archaeological geomatics - the majick of spatial data in archaeology - archaeological information systems for the digital age:

Mapping rubble by Brian Hoffman

Mapping rubble by Brian Hoffman

The first investigation in the GeoSemantic Technologies for Archaeological Research (GSTAR) research project is nearing completion, an assessment of approaches to the integration of geospatial archaeological data into a semantic framework to provide geosemantic capabilities.

The investigation draws on archaeological excavation data lodged with the Archaeology Data Service (ADS) and made available as Linked Data (LD) through the ADS’s Linked Data platform. The data relates to the Cobham Golf Course site and was produced by Oxford Archaeology (OA) as part of the Channel Tunnel Rail Link (CTRL) project then turned into a Linked Data resource through the Semantic Technologies Enhancing Links and Linked data for Archaeological Resources (STELLAR) project, undertaken by the Hypermedia Research Unit at the University of South Wales (USW).

Mapping a feature by Wessex Archaeology

Mapping a feature by Wessex Archaeology

The GSTAR literature review identified two strands of integration approaches within published literature. Emerging from the semantic web and Linked Data communities, an approach involving the direct inclusion of geospatial data within semantic resources, leveraging World Wide Web Consortium (W3C) standards for Resource Description Framework (RDF) and Open Geospatial Consortium (OGC) standards for Well Known Text (WKT, part of the Simple Features specification) and GeoSPARQL. Emerging from the Geographic Information Science (GISc) community, approaches involving the use of Web Feature Services (WFS) within broader Spatial Data Infrastructures (SDI) running in parallel and linked to to semantic resources.

This initial GSTAR investigation looked at both these strands with a view to assessing suitable modes for subsequent use in the next phases of the GSTAR project. A WISSKI installation has also been setup to allow for the minting of any additional URIs needed.

GeoSPARQL route

This involved creating geosemantic data aligned with the CRM-EH extension to the CIDOC CRM ontology, stored within the Oracle Spatial & Graph platform and accessed via GeoSPARQL using an Oracle WebLogic web server and the Jena Framework.

[code language="xml"]
<owl:Class rdf:about="http://purl.org/crmeh#EHE0022_ContextDepiction">
<rdfs:isDefinedBy rdf:resource="http://purl.org/crmeh#CRMEH"/>
<rdfs:subClassOf rdf:resource="http://erlangen-crm.org/110404/E47_Spatial_Coordinates"/>
<rdfs:label>Context Depiction</rdfs:label>
<rdfs:comment>
The Spatial co-ordinates of a Context, defining the actual spatial extent of the context. Usually recorded at the time of excavation or other investigative work
</rdfs:comment>
</owl:Class>
[/code]
The OWL definition of the EHE0022 class used to describe depictions

Further triples were also added to describe the depiction using the GeoSPARQL ogc:hasGeometry and ogc:asWKT properties.

[code language="xml"]
<owl:ObjectProperty rdf:about="#hasGeometry">
<rdfs:isDefinedBy rdf:resource=""/>
<rdfs:isDefinedBy rdf:resource="http://www.opengis.net/spec/geosparql/1.0"/>
<skos:prefLabel xml:lang="en">hasGeometry</skos:prefLabel>
<dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#date">2011-06-16</dc:date>
<dc:contributor>Matthew Perry</dc:contributor>
<dc:description xml:lang="en">
A spatial representation for a given feature.
</dc:description>
<rdfs:range rdf:resource="#Geometry"/>
<rdfs:comment xml:lang="en">
A spatial representation for a given feature.
</rdfs:comment>
<rdfs:domain rdf:resource="#Feature"/>
<rdfs:label xml:lang="en">hasGeometry</rdfs:label>
<dc:creator>OGC GeoSPARQL 1.0 Standard Working Group</dc:creator>
<skos:definition xml:lang="en">
A spatial representation for a given feature.
</skos:definition>
</owl:ObjectProperty>
[/code]

The OWL definition of the hasGeometry property

GIS Server route

A second approach used the same base platform and data but accessed the geospatial component via WFS provided by GeoServer, drawing on the Oracle database.

Next steps

The results of this stage and the GSTAR project in general will be presented at the Computer Applications and Quantitative Methods in Archaeology (CAA) conference to be held in Paris, France during April 2014.

Thanks are due to the University of South Wales for funding the GSTAR project and to the people and organisations responsible for the tools, technologies and data being used. Also my PhD supervisor (Prof. Douglas Tudhope; USW), advisors (Dr Mark Ware and Dr Alex Lohfink: USW) and fellow researchers Ceri Binding (USW), Dr Andreas Vlachidis (USW) and Michael Charno (ADS) for their input.

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Some detailed modelling – archaeological excavation data

Pottery

Pottery

As part of my PhD research, the GSTAR project, I’ve been doing some more detailed work data modelling using the CRM-EH extensions to the CIDOC CRM, looking specifically at the concepts of ‘context’ aka ‘stratigraphic unit’ and how to model stratigraphy and context specialisms and relationships. Also the related processes by which objects become deposited in archaeological contexts and are subsequently found.

I will hopefully be publishing this work more fully in due course but for now here is a taster of some of the preliminary results.

This is very much open for discussion so any comments gratefully received.

Contexts and Stratigraphy: Positive and Negative Stratigraphic Units and related Events

The context is the fundamental unit of recording in many archaeological recording systems. We can think of archaeological contexts, representing discreet stratigraphic units, as being of two basic classes: Positive and Negative.

Positive Stratigraphic Units describe layers and deposits, ie the result of some material being deposited in a place whilst Negative Stratigraphic Units represent cuts, ie the result of some material being removed from a place.

Contexts and Specialisms

Contexts and Specialisms

Stratigraphy can be seen as the relative sequence of events resulting in these changes to archaeological deposits. A shortcut is used here for stratigraphically above/below (more accurately stratigraphically before/after) to provide a short chain representing this much longer sequence of events and event relationships.

Contexts and Stratigraphy

Contexts and Stratigraphy

Context Types and Relationships

All types of contexts have physical relationships with other contexts. The types of relationships depends on the type of context. Properties inherited from parent classes likewise.

Contexts can all be seen as subclasses of an overarching concept, the stratigraphic unit. These subclasses are generally represented in recording systems using different context sheets each holding common properties such as UIDs and classifications and also type specific properties such as physical relationships. Subtypes include masonry, timber and skeletons.

Context Relationships

Context Relationships

Finds deposition

Finds can be seen as ending up in archaeological deposits through some move event which could be a deliberate action or otherwise (eg an accidental loss). This forms one of the chain of events relating to objects beginning with their creation and initial use and/or display and eventually continuing beyond their rediscovery into the display and changes of custody in the world of museums and collections.

Finds Deposition

Finds Deposition

In addition to the act of discovery, however that may occur, a whole sequence of events then results in assignment of identifiers and classification using typologies.

Find discovery

Find discovery