GeoSPARQL: false positives finding points inside polygons (st_within and st_contains)

[guiveg]

I'm using Version 7.2.8.3235-pthreads of Virtuoso Open Source Edition with Docker.

I'm using GeoSPARQL with function bif:st_within in order to find which set of points are enclosed in a set of polygons. Apparently it works, but I've found lots of false positives, i.e. a point may be assigned to several polygons that are not overlapped.

I've isolated the problem in the attached turtle file, containing a plot with a point geometry and two municipalities, each one with a polygon geometry. The attached pdf shows a map the two municipalities (01042 and 48045) and the plot (yellow point).

I've tried this query:

select distinct ?plot ?muni where {
?plot a <http://prueba.es/Plot> ;
   <http://www.opengis.net/ont/geosparql#asWKT> ?wktp .
?muni a <http://prueba.es/Municipality> ;
    <http://www.opengis.net/ont/geosparql#asWKT> ?wktm .   
FILTER ( bif:st_contains( ?wktm, ?wktp ) ) 
}

And I get these results:

plot | muni
-- | --
http://prueba.es/plot/01-0002-A-4C | http://prueba.es/municipality/01042
http://prueba.es/plot/01-0002-A-4C | http://prueba.es/municipality/48045

I've also tried with bif:st_within instead of bif:st_contains with the same result.

Then, I've tried a new query using bif:st_point to create a point with the same coordinates of the plot:

select distinct ?muni where {
?muni a <http://prueba.es/Municipality> ;
    <http://www.opengis.net/ont/geosparql#asWKT> ?wktm .   
FILTER ( bif:st_contains( ?wktm, bif:st_point(-3.02588, 43.206889) ) ) 
}

Now I get the correct result:

muni
--
http://prueba.es/municipality/01042

But if I try the previous query with bif:st_within as in:

select distinct ?muni where {
?muni a <http://prueba.es/Municipality> ;
    <http://www.opengis.net/ont/geosparql#asWKT> ?wktm .   
FILTER ( bif:st_within( bif:st_point(-3.02588, 43.206889), ?wktm ) ) 
}

Then I've obtained again a false positive:

muni
--
http://prueba.es/municipality/01042
http://prueba.es/municipality/48045

In conclusion, the functioning of functions bif:st_within and bif:st_contains looks buggy to me. I hope it can be fixed.

pruebageo.txt

map.pdf

[HughWilliams]

We are looking into this issue ...