Resource discovery in a European Spatial Data Infrastructure

The geospatial community is moving toward distributed databases and Web services by following the general developments in information and communication technology. The sharing of resources across multiple information communities raises the need of new technologies that support resource discovery and information retrieval. This paper investigates if a common ontology is desirable and feasible for information retrieval in a European Spatial Data Infrastructure. It does so by reviewing relevant literature and proposes an approach for the automatic updating of existing ontologies, designed to facilitate access to multilingual descriptors of geospatial resources. We demonstrate by means of a prototype of an experimental system that the proposed approach is feasible. The experimental system is unique because it integrates a gazetteer, the EuroVoc multilingual vocabulary, the GEMET multilingual thesaurus, an automatic concept space generator, and graph matching into one system. Based on our study, we conclude that it will be impractical to rely only on one common ontology for resource discovery. We also conclude that the approach of using human-created ontologies in combination with automatic concept space generation and associative retrieval is a powerful means to the discovery of geospatial resources. In the absence of a consistent use of semantic Web technologies, a centralized approach to indexing of metadata is required, which has consequences for architectural choices.