Spatial distance in Fuseki

[Markus Neumann]

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