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Representation and querying of linked geospatial data- tutorial

Representation and querying of linked geospatial data- tutorial. Konstantina Bereta 10/02/2014. Example in stRDF. gag:Olympia gag:name "Ancient Olympia "; rdf:type gag:MunicipalCommunity . Spatial literal.

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Representation and querying of linked geospatial data- tutorial

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  1. Representation and querying of linked geospatial data- tutorial KonstantinaBereta 10/02/2014

  2. Example in stRDF gag:Olympia gag:name"Ancient Olympia"; rdf:typegag:MunicipalCommunity . Spatial literal gag:Olympiagag:geometry "POLYGON((21.5 18.5, 23.5 18.5, 23.5 21, 21.5 21, 21.5 18.5)); <http://www.opengis.net/def/crs/EPSG/0/4326>"^^ strdf:WKT . Spatial data type 2

  3. Example in GeoSPARQL gag:Olympia rdf:typegag:MunicipalCommunity; gag:name"Ancient Olympia"; gag:population"184"^^xsd:int; geo:hasGeometryex:polygon1. ex:polygon1 rdf:typegeo:Geometry; geo:asWKT "POLYGON((21.5 18.5,23.5 18.5, 23.5 21,21.5 21,21.5 18.5)) "^^sf:wktLiteral. Property from Geometry extension Spatial literal Spatial data type 3

  4. stSPARQL: Geospatial SPARQL 1.1 • We define a SPARQL extension function for each function defined in the OpenGIS Simple Features Access standard • Basic functions • Get a property of a geometry • xsd:intstrdf:dimension(strdf:geometry A) • xsd:stringstrdf:geometryType(strdf:geometryA) • xsd:intstrdf:srid(strdf:geometry A) • Get the desired representation of a geometry • xsd:stringstrdf:asText(strdf:geometryA) • xsd:stringstrdf:asGML(strdf:geometryA) • Test whether a certain condition holds • xsd:booleanstrdf:isEmpty(strdf:geometryA) • xsd:booleanstrdf:isSimple(strdf:geometryA) 4

  5. stSPARQL: Geospatial SPARQL 1.1 • Functions for testing topological spatial relationships • OGC Simple Features Access • xsd:booleanstrdf:equals(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:disjoint(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:intersects(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:touches(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:crosses(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:within(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:contains(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:overlaps(strdf:geometryA, strdf:geometry B) • xsd:booleanstrdf:relate(strdf:geometryA, strdf:geometry B, • xsd:stringintersectionPatternMatrix) • Egenhofer • RCC-8 5

  6. stSPARQL: Geospatial SPARQL 1.1 • Spatial analysis functions • Construct new geometric objects from existing geometric objects • strdf:geometrystrdf:boundary(strdf:geometry A) • strdf:geometrystrdf:envelope(strdf:geometry A) • strdf:geometrystrdf:convexHull(strdf:geometry A) • strdf:geometrystrdf:intersection(strdf:geometry A, strdf:geometry B) • strdf:geometrystrdf:union(strdf:geometry A, strdf:geometry B) • strdf:geometrystrdf:difference(strdf:geometry A, strdf:geometry B) • strdf:geometrystrdf:symDifference(strdf:geometry A, strdf:geometry B) • strdf:geometrystrdf:buffer(strdf:geometry A, xsd:double distance, xsd:anyURI units) • Spatial metric functions • xsd:floatstrdf:distance(strdf:geometry A, strdf:geometry B, xsd:anyURI units) • xsd:floatstrdf:area(strdf:geometry A) • Spatial aggregate functions • strdf:geometrystrdf:union(set of strdf:geometry A) • strdf:geometrystrdf:intersection(set of strdf:geometry A) • strdf:geometrystrdf:extent(set of strdf:geometryA) 6

  7. GeoSPARQL Topology Vocabulary Extension • The extension is parameterized by the family of topological relations supported. • Topological relations for simple features • The Egenhofer relations e.g., geo:ehMeet • The RCC-8 relations e.g., geo:rcc8ec 7

  8. The system Strabon • Data model: stRDF • Query language: stSPARQL/GeoSPARQL • Use of OGC standards(Well-Known Text and GML) 8

  9. The system Strabon (cont’d) WKT GML [ ISWC 2012 ] stRDFgraphs stSPARQL/ GeoSPARQL queries 9

  10. links • Strabon endpoint installation guide • Strabonwebsite • stSPARQLreference • Greek Linked Open Data datasets

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