GeoSPARQL

GeoSPARQL is a standard for representation and querying of geospatial linked data for the Semantic Web from the Open Geospatial Consortium (OGC). The definition of a small ontology based on well-understood OGC standards is intended to provide a standardized exchange basis for geospatial RDF data which can support both qualitative and quantitative spatial reasoning and querying with the SPARQL database query language.

The Ordnance Survey Linked Data Platform uses OWL mappings for GeoSPARQL equivalent properties in its vocabulary. The LinkedGeoData data set is a work of the Agile Knowledge Engineering and Semantic Web (AKSW) research group at the University of Leipzig, a group mostly known for DBpedia, that uses the GeoSPARQL vocabulary to represent OpenStreetMap data.

In particular, GeoSPARQL provides for:

• a small topological ontology in RDFS/OWL for representation using
  • Geography Markup Language (GML) and well-known text (WKT) literals, and
  • Simple Features, RCC8, and DE-9IM (a.k.a. Egenhofer) topological relationship vocabularies and ontologies for qualitative reasoning, and
• a SPARQL query interface using
  • a set of topological SPARQL extension functions for quantitative reasoning, and
  • a set of Rule Interchange Format (RIF) Core inference rules for query transformation and interpretation.

Example

The following example SPARQL query could help model the question "What is within the bounding box defined by and ?"

PREFIX geo: <http://www.opengis.net/ont/geosparql#>
PREFIX geof: <http://www.opengis.net/def/geosparql/function/>

SELECT ?what
WHERE {
  ?what geo:hasGeometry ?geometry .

  FILTER(geof:sfWithin(?geometry,
     "POLYGON((
-77.089005 38.913574,
-77.029953 38.913574,
-77.029953 38.886321,
-77.089005 38.886321,
-77.089005 38.913574
))"^^geo:wktLiteral))
}

RCC8 use in GeoSPARQL

RCC8 has been implemented in GeoSPARQL as described below:

File:Region Connection Calculus 8 Relations and Open Geospatial Consortium relations.svg

A graphical representation of Region Connection Calculus (RCC: Randell, Cui and Cohn, 1992) and the links to the equivalent naming by the Open Geospatial Consortium (OGC) with their equivalent URIs.

Implementations

There are (almost) no complete implementations of GeoSPARQL, there are, however partial or vendor implementations of GeoSPARQL. Currently there are the following implementations:

Apache Marmotta

Apache Marmotta is currently implementing GeoSPARQL in the context of the Google Summer of Code 2015.

Parliament

Parliament has an almost complete implementation of GeoSPARQL by using JENA and a modified ARQ query processor.

Strabon

OpenSahara uSeekM IndexingSail Sesame Sail plugin

uSeekM IndexingSail uses a PostGIS installation to deliver GeoSPARQL. They deliver partial implementation of GeoSPARQL along with some vendor prefixes.

Oracle Spatial and Graph

Submission

The GeoSPARQL standard was submitted to the OGC by:

• Australian Bureau of Meteorology
• Bentley Systems
• Commonwealth Scientific and Industrial Research Organisation (CSIRO)
• Defence Geospatial Information Working Group (DGIWG)
• Natural Resources Canada
• Interactive Instruments GmbH
• Oracle America
• Ordnance Survey
• Raytheon
• Traverse Technologies
• US Geological Survey (USGS)

Related work

With regards to future work, the GeoSPARQL standard states:

Obvious extensions are to define new conformance classes for other standard serializations of geometry data (e.g. KML, GeoJSON). In addition, significant work remains in developing vocabularies for spatial data, and expanding the GeoSPARQL vocabularies with OWL axioms to aid in logical spatial reasoning would be a valuable contribution. There are also large amounts of existing feature data represented in either a GML file (or similar serialization) or in a datastore supporting the general feature model. It would be beneficial to develop standard processes for converting (or virtually converting and exposing) this data to RDF.

External links

• Linked Data Platform webapps from the UK Ordnance Survey
• LinkedGeoData for OpenStreetMap data
• GeoSPARQL – A Geographic Query Language for RDF Data standard from the Open Geospatial Consortium