Hello Hugh,
Thank you for the explanation. It confirms my observations. With
extended functionality in the next release, do you mean that the actual
haystack shape will be used instead of its bounding box, like its says
in the documentation of the function st_within?
And can we assume that similar functions like st_intersects and
st_contains also only operate on bounding boxes of geometries at the moment?
Regards,
Frans
On 2014-03-21 2:59, Hugh Williams wrote:
Hi Frans,
The "st_within" geometry function checks whether a haystack_shape contains the
needle_shape. If proximity is specified, it is treated as an extra wide border around
haystack_shape. In currnet version, only a combination of bounding box and a point is
supported, this functionality will be extended in the next release.
I hope this answers your question. Genarally, if you can provide some sample
data and the queries being run it would help in understanding of the issue
being reported ...
Best Regards
Hugh Williams
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On 20 Mar 2014, at 13:12, Frans Knibbe | Geodan <frans.kni...@geodan.nl> wrote:
Hello,
I have loaded some spatial data in Virtuoso Open Source 7.1. The geometries are
polygons and multipolygons. The geometries are adjacent to each other, they do
not overlap. However, when I tried a SPARQL query with a FILTER bif:st_within,
to get the polygon that contains a certain point that I specify in the query,
the first test I performed returned two geometries. I do not use the tolerance
parameter of st_within, so that should be 0.
The geometries are exported from PostGIS and I can draw the original geometries
in a map. Doing that gives me a visual confirmation that the query should only
return one geometry.
Based on my simple test, I get the impression that st_within works with the
bounding box of a geometry, not the geometry itself. Can this be confirmed or
denied?
Regards,
Frans
Frans Knibbe
Geodan
President Kennedylaan 1
1079 MB Amsterdam (NL)
T +31 (0)20 - 5711 347
E frans.kni...@geodan.nl
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Geodan
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