ArticleRead (16): Towards a semantics-based approach in the development of geographic portals

Towards a semantics-based approach in the development of geographic portals, By Nikolaos Athanasis, Kostas Kalabokidis, Michail Vaitis, Nikolaos Soulakellis,In Computers & Geosciences, 35(2009)301–308

Athanasis et al. (2009) have proposed and implemented a geoportal with the aim of providing a methodology for geospatial information discovery with a new approach responsive to what we understand to be significant issues of the Semantic Web on RDF and ontology-based metadata.

By taking advantages of multiple ontology design, they advocate the ontology-based metadata organization into three special context (three schemas: content type, application domain, and the ISO 19115 metadata standard) to enhance users’ navigation techniques in the geoportal interface as a solution to response to the keyword search problem.

In addition to the difficulty of appropriate search criteria they have identified, problems such as semantic heterogeneity (cognitive and naming heterogeneity in particular), the limitation of expressiveness of queries, or the lack/ discrepancy of geospatial metadata standard at the implementation stage are discussed.

Their solutions to these difficulties by focusing on the relationship among geoportals, users, and information providers in a geoportal infrastructure are described as follow:


(1) propose a RDF-based metadata organisation method using multiple ontologies.

(2) design a interface for information providers to describe characters of new resources, characterise their possible relationships between related resources, and classify them based on the build-in RDF classes of metadata schemas.

(3) auto-translate the submitted data into RDF metadata descriptions stored in PostgreSQL, and maintained by the ICS-FORTH RDFSuite (Alexaki et al.,2001) which enables the validation, storage, and querying of the RDF metadata (both schemas and data descriptions).

(4) use RDF Query Language (RQL) based on a formal graph model, and which are executed in a SQL-like “select-from-where” pattern.

Final comments: the implementation is still a prototype supported by the EU RTD project and the website is : http://incendi.geo.aegean.gr/en/incendi_aggl.html . The future work of this team is to develop OWL.