geof:distance not work with MULTIPOLYGON

[siwenyang]

Hi there,

I am trying some queries with geosqarl.

In the OSM Germany, I tried query the distance of all Germany provinces to a certain Point(7.85 48.00).

Here is my query:

PREFIX geo: <http://www.opengis.net/ont/geosparql#>
PREFIX geof: <http://www.opengis.net/def/function/geosparql/>
PREFIX osm: <https://www.openstreetmap.org/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX osmkey: <https://www.openstreetmap.org/wiki/Key:>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?region ?name ?dist ?geometry WHERE {
  ?region osmkey:boundary "administrative" .
  ?region osmkey:admin_level "4"^^xsd:int .
  ?region rdf:type osm:relation .
  ?region osmkey:name ?name .
  ?region geo:hasGeometry ?geometry .
  BIND (geof:distance(?geometry, "POINT(7.85 48.00)") AS ?dist) .
}

But all dist result from the query is nan:

Could you kindly let me if Qlever support this feature? or it is my query problem?

Thank you so much.

[joka921]

Hi,
Your query is perfectly fine, but QLever currently has only very limited support for GeoSPARQL. Most notably, the geof:distance function is only implemented between two points, and not between a point and an arbitrary geometric shape. One our goals is to support more GeoSPARQL, but I can't currently give you an estimate on a realistic timeframe.

[siwenyang]

Hi there,

Thank you for the reply and information.

Hopefullly, we can see more support on GeoSPARQL soon! It would be great.

[1ec5]

One of the OpenHistoricalMap example queries on the OSM Wiki finds POIs that have moved the farthest over time, with the caveat that the POIs must be mapped as nodes. But distances between polygon or multipolygon centroids would let us enhance the query to find other things that have moved, such as buildings or shops that are typically mapped as areas.