Visualizing Linked Geospatial Data

Abstract

8.1 The Tool Sextant Sextant is a Web-based platform for visualizing, exploring, and interacting with linked geospatial data. Sextant focuses on creating a user-friendly environment that would allow both domain experts and non-experts to take advantage of Semantic Web technologies. The core feature of Sextant is the ability to create thematic maps by combin­ ing geospatial and temporal information that exists in heterogeneous data sources ranging from widely adopted geospatial file formats like KML, GML, GeoJSON, WMS, and GeoTIFF to standard SPARQL endpoints to GeoSPARQL endpoints. In this manner, we provide functionality to domain experts from different fields in creating thematic maps, which emphasize the spatial variation of one or a small number of geographic distributions. Moreover, Sextant introduces a map ontology that assists on modeling these maps in RDF and allow for easy sharing, editing, and search mechanisms over existing maps. Another important feature is the utilization of the temporal dimension. Imple­ mentation of the valid time component of stRDF and stSPARQL in the system Strabon allows us to query both the spatial and the temporal dimensions. Enrich­ ing our results with temporal information allows us to create layers with valid time. Using a timeline, we can make these layers appear and disappear from the map according to their valid time. This feature allows the creation of thematic maps that