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SPARQL

Query: BKG DLM250 (wfs_dlm250_inspire); Two INSPIRE classes, one country (UNION); Spatial relations (geof:sfCrosses); Attribute lookup (eq=); Cross-border (DE/CZ); Cross-border (DE/PL); PREFIX hy-p: <inspire/hy-p/4.0#> SELECT ?s ?name ?length FROM <wfs?s=https://sgx.geodatenzentrum.de/wfs_dlm250_inspire&type=/inspire/hy-p/4.0%23Watercourse&bbox=9.90,53.50,10.10,53.60> WHERE { ?s a hy-p:Watercourse ; hy-p:geographicalName ?name ; hy-p:length ?length . } LIMIT 10; — SPARQL query link (copy for curl; the # in FROM IRIs becomes %23)

FROM — selecting the data

Every query needs at least one FROM (or FROM NAMED); the processor fetches those documents and queries over them. Only THIS wrapper's documents are permitted, and relative IRIs resolve against the wrapper root — so the same query works on any deployment:

FROM </wfs?s={service}&type=/inspire/{theme}/{version}%23{Class}&bbox=W,S,E,N> — a bounding-box document, feature type named by its RDF class URI (the s= value URL-encoded)
FROM </wfs?s={service}&typenames={prefix}:{Type}&bbox=…> — the same, addressed by the native WFS typename instead. Use this for services whose types are not INSPIRE-namespaced
FROM </wfs?s={service}&id={featureid}> — one feature's document
FROM </inspire/{theme}/{version}>, FROM </vocab/{name}> — the vocabularies themselves (classes, properties, definitions and multilingual labels), queryable like any other graph
&count= / &offset= page a large answer; &time= requests a Memento of it

Several FROM clauses merge into one graph. A # inside a FROM IRI must be written %23.

GeoSPARQL functions

The processor registers the GeoSPARQL 1.1 function suite (OGC 22-047r1). Functions operate on geo:wktLiteral and geo:gmlLiteral typed literals — the form produced by all data sources here. Common functions relevant to this dataset:

geof:metricArea(?g) — geodesic area in m²
geof:metricLength(?g) — geodesic length in m
geof:metricDistance(?a, ?b) — geodesic distance in m
geof:centroid(?g) — returns a geo:wktLiteral POINT

Topological relations (DE-9IM / Simple Features) return a boolean for a pair of geometries:

geof:sfEquals(?a, ?b) — topologically equal
geof:sfTouches(?a, ?b) — boundaries meet, interiors do not
geof:sfCrosses(?a, ?b) — interiors cross (e.g. a bridge line over a watercourse)
geof:sfIntersects(?a, ?b) — not disjoint
geof:sfContains(?a, ?b) — ?a contains ?b

Use PREFIX geof: <http://www.opengis.net/def/function/geosparql/>.

A non-standard helper returns a geometry's topological dimension as an integer (0 point, 1 curve, 2 surface):

fn:dimension(?g) — mirrors JTS getDimension(); test for curve/area with fn:dimension(?g) = 1 / = 2

Use PREFIX fn: <https://inspirewrap.ontologycentral.com/vocab/fn#>. These reproduce the ATKIS SK50 styling-rule predicates (mdl:geo_crosses → geof:sfCrosses, mdl:geo_isArea → fn:dimension(?g) = 2, etc.). See the example dropdown above for working queries.