I'm no expert on Jena's GeoSPARQL support, but our docs: https://jena.apache.org/documentation/query/spatial-query.html
don't mention any such namespaces as http://www.opengis.net/rdf/functions#. Where did you see it documented that Jena supports such functions? I only see a small and specific set of functions: https://jena.apache.org/documentation/query/spatial-query.html#property-function-library but you could certainly use Jena's extension mechanisms to do this kind of calculation: https://jena.apache.org/documentation/query/writing_propfuncs.html although it's not trivial to do that. Perhaps a committer with more knowledge about jena-spatial can help here. ajs6f > On Aug 24, 2018, at 5:47 AM, Markus Neumann <mneum...@meteomatics.com> wrote: > > Hi, > > I'm quite new to both Fuseki and mailinglists, so please be patient with me. > > I've managed to set up a Fuseki 2 server together with a Lucene spatial index. > E.g the following query works as expected: > > PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> > PREFIX geosparql: <http://www.opengis.net/ont/geosparql#> > PREFIX mm: <http://rdf.meteomatics.com/mm/> > PREFIX spatial: <http://jena.apache.org/spatial#> > SELECT * > WHERE { > ?loc spatial:nearby (47.5 8.5 5 'km') . > ?loc a mm:Location; > geo:lat ?lat; > geo:long ?long; > geosparql:asWKT ?wkt; > mm:station_name ?name. > } > > Now I would like to run the following: > > PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> > PREFIX geosparql: <http://www.opengis.net/ont/geosparql#> > PREFIX mm: <http://rdf.meteomatics.com/mm/> > PREFIX spatial: <http://jena.apache.org/spatial#> > PREFIX ogcf: <http://www.opengis.net/rdf/functions#> > SELECT ?distance WHERE { > BIND(mm-locations:8515451 as ?wil) > ?wil spatial:nearby(?lat ?lon 8 'km') . > ?wil geosparql:asWKT ?wil_wkt . > ?loc a mm:Location; > geo:lat ?lat; > geo:long ?lon; > geosparql:asWKT ?wkt. > BIND( ogcf:distance(?wil_wkt, ?wkt, 'km') as ?distance) > } > > The query completes and gets the correct amount of results, but all wihout > value. > In the log pops up this message: > > [2018-08-24 09:45:33] exec WARN URI > <http://www.opengis.net/rdf/functions#distance> has no registered function > factory > > Is there a way to get this to work? Or is there another way to compute > spatial distances? > > Many thanks for your time. > > Best regards > Markus >
