Geospatial databases

Do you want to get the most of your relational data combining them with linked geospatial data without converting them to RDF? No problem. Ontop-spatial can create virtual geospatial RDF graphs on top of your geospatial databases (Currently PostGIS, SpatiaLite and Oracle spatial are supported). Your geometries will be mapped to GeoSPARQL geometry literals using ontologies and R2RML/OBDA mappings.

GeoSPARQL support

Ontop-spatial supports the following GeoSPARQL components: core, Topology vocabulary, Geometry topology extension, RDFS entailment extension, Query rewrite extension and subset of the Geometry Extension.


As its parent system, Ontop, Ontop-spatial can be used as a standard SPARQL endpoint that can execute GeoSPARQL queries on top of geospatial databases. Therefore, it can be used complementarily with other tools that produce, manage, explore, and visualize geospatial RDF data. For example, R2R2ML mappings generated by GeoTriples can be given as input to Ontop-spatial to create a virtual geospatial repository. Also, the geometries of an Ontop-spatial repository can be visualized using Sextant, a web-based tool for browsing and visualizing linked geospatial data. An Ontop-spatial endpoint can also be used as source endpoint to the linking tool Silk, that has recently been extended with geospatial features. Last but not least, the virtual geospatial RDF graphs produced by Ontop-spatial can be materialized and stored in a geospatial RDF store (e.g., Strabon).


Deciding to create virtual geospatial RDF graphs instead of materializing them does not necessarily mean that efficiency needs to be sacrificed. In fact, experimental evaluation has shown that in most cases, Ontop-spatial achieves better response times than traditional geospatial RDF stores

Ontop-spatial in use

Additional material


  • Konstantina Bereta, Guohui Xiao and Manolis Koubarakis. Answering GeoSPARQL quereis over relational data. 3rd European Conference on Free and Open Source Software for Geospatial systems (FOSS4G-E ), Paris, France, 18 - 22 July, 2017 [pdf]

  • Konstantina Bereta and Manolis Koubarakis. Ontop of Geospatial Databases . International Semantic Web Conference (ISWC), Kobe, Japan, 17-21 October 2016 [pdf]

  • Konstantina Bereta, Guohui Xiao, Manolis Koubarakis, Martina Hodrius, Conrad Bielski, and Gunter Zeug. Ontop-spatial: Geospatial Data Integration using GeoSPARQL-to-SQL Translation. International Semantic Web Conference (ISWC), Kobe, Japan, 17-21 October 2016. Demo paper [pdf]


  • prof. Manolis Koubarakis and Konstantina Bereta gave a tutorial at ISWC 2017 in Vienna with title "ReQuLGD: Representation and Querying for Linked Geospatial Data"
  • Konstantina Bereta gave a presentation about Ontop-spatial with title "Ontop of geospatial databases" at the 15th International Semantic Web Conference (ISWC 2016) at Kobe, Japan [pdf]
  • A demo of Ontop-spatial used in a Crisis mapping application (that monitors floods) and a land management application was presented at ISWC 2016 In Kobe, Japan. Demo title: Ontop-spatial: Geospatial Data Integration using GeoSPARQL-to-SQL Translation[pdf]
  • Konstantina Bereta gave a presentation on the use of Ontop-spatial in the context of a maritime application at the industrial track of ESWC 2016. [pdf]