Aggregation Operators in Geospatial Queries for Open Street Map

Abstract

One of the most stablished Volunteered Geographic Informa- tion (VGI) systems is Open Street Map (OSM) offering data from the earth of urban and rural maps. Recently [1], we have presented a library for querying OSM data with the XML query language XQuery. This li- brary is based on the well-known spatial operators defined by Clementini and Egenhofer, providing a repertoire of XQuery functions which encap- sulates the search on the XML document representing a layer of OSM, and makes the definition and composition of queries on top of OSM layers easier. This paper goes towards the incorporation in the library of aggregation operators in order to be able to express queries involv- ing data summarization and ranking. A rich repertoire of aggregation operators has been defined which, in combination with the previously proposed library, makes possible to easily formulate aggregation-based queries. Also we present a Web-based tool, called XOSM (XQuery for Open Street Map), developed in our group, that uses the proposed library to query and visualize OSM data.