Efficient access to heterogeneous environmental data repositories through linked data standards

Abstract

This Thesis proposes advances in various components of a new GeoSPARQL query engine, called GeoLD, that enables the efficient integrated querying of heterogeneous environmental datasets, including Vector Features and Raster Coverages, which are available through standard web services of geospatial data infrastructures. The proposed solution enables the access to Raster Coverages by providing a new Coverage to RDF Mapping Language (C2RML), which enables the programmer to incorporate specific vocabularies during the definition of the mapping between the coverage data schema and RDF. New SPARQL operators and a new query optimization strategy provide the algorithms required to reach query response times orders of magnitude faster than those of state of the art technologies. Additionally, contrary to existing approaches, raster data querying is achieved without the need to use large lists of specific raster manipulation functions, which simplifies the programming task.