[postgis-users] Center of Points

[Jens Werdin]

This is my version:
POSTGIS="1.1.0" GEOS="2.2.1-CAPI-1.0.1" PROJ="Rel. 4.4.9, 29 Oct 2004" 
USE_STATS




Am Donnerstag, 9. März 2006 14:42 schrieb Gustavo Henrique Sberze Ribas:
> Hallo,
>
> > I'm using postgis 1.1.0 on a postgres 8.1.2.
> > if i'm using your query as it is, i'm getting POINT(nan nan) too.
>
>   Well, I've forgot to include commas to separate the points. This
> wasn't an issue with PostGIS 0.9 but version 1.0 complained about it.
> Anyway, I've tested it against the versions I had available:
>
> POSTGIS="1.0.1" GEOS="2.1.1" PROJ="Rel. 4.4.9, 29 Oct 2004" USE_STATS
> DBPROC="0.3.0" RELPROC="0.3.0" PostgreSQL 8.0.3
> and
> POSTGIS="0.9.0" GEOS="2.0.1" PROJ="Rel. 4.4.8, 3 May 2004" USE_STATS
> DBPROC="0.0.1" RELPROC="0.0.1" PostgreSQL 8.0.0
>
> both worked. Perhaps there's something wrong with your installation?
>
> > if i'm adding a convexhull on the geomcoll I get a POINT, but
> > i think it is the center of the hull and not the center of the points.
>
>  You're right. Just in case you're curious (I was) the green point in the
> attached picture shows the convex hull's centroid. The numeric results
> are
>   pointscentroid = POINT(-47.3229673751195 -22.7344596651925)
>   convexhullcentroid  = POINT(-47.3570658875554 -22.6784457605688)
> the query I used is attached below.
>
> Servus,
> Gustavo
>
> --
>
> select asText(centroid(geomCollFromText('GEOMETRYCOLLECTION(
> POINT(-47.2412222222222 -22.7405833333333),
> POINT(-47.3199166666667 -22.7333333333333),
> POINT(-47.3545555555556 -22.7443055555556),
> POINT(-47.3008346557617 -22.7133331298828),
> POINT(-47.3302764892578 -22.731388092041),
> POINT(-47.3406111111111 -22.76525),
> POINT(-47.29525 -22.7161388888889),
> POINT(-47.3481666666667 -22.7247222222222),
> POINT(-47.3160277777778 -22.7383888888889),
> POINT(-47.3275 -22.7459722222222),
> POINT(-47.34025 -22.7523333333333),
> POINT(-47.3368988037109 -22.7385997772217),
> POINT(-47.3527793884277 -22.7352771759033),
> POINT(-47.3476388888889 -22.7324444444444),
> POINT(-47.3481666666667 -22.7247222222222),
> POINT(-47.2624722222222 -22.7496944444444),
> POINT(-47.34025 -22.7523333333333),
> POINT(-47.3160277777778 -22.7383888888889),
> POINT(-47.3406111111111 -22.76525),
> POINT(-47.3275 -22.7459722222222),
> POINT(-47.3001944444444 -22.7144444444444),
> POINT(-47.3520555555556 -22.7320277777778),
> POINT(-47.2952222222222 -22.7311111111111),
> POINT(-47.3071944444444 -22.7513888888889),
> POINT(-47.2978611111111 -22.7079722222222),
> POINT(-47.3025833333333 -22.7260555555556),
> POINT(-47.3317777777778 -22.7485),
> POINT(-47.2861111111111 -22.7694444444444),
> POINT(-47.2861111111111 -22.7722222222222),
> POINT(-47.2944444444444 -22.775),
> POINT(-47.2861111111111 -22.7805555555556),
> POINT(-47.5083333333333 -22.5055555555556))',4326))) as PointsCentroid
> ,asText(centroid(convexhull(geomCollFromText('GEOMETRYCOLLECTION(
> POINT(-47.2412222222222 -22.7405833333333),
> POINT(-47.3199166666667 -22.7333333333333),
> POINT(-47.3545555555556 -22.7443055555556),
> POINT(-47.3008346557617 -22.7133331298828),
> POINT(-47.3302764892578 -22.731388092041),
> POINT(-47.3406111111111 -22.76525),
> POINT(-47.29525 -22.7161388888889),
> POINT(-47.3481666666667 -22.7247222222222),
> POINT(-47.3160277777778 -22.7383888888889),
> POINT(-47.3275 -22.7459722222222),
> POINT(-47.34025 -22.7523333333333),
> POINT(-47.3368988037109 -22.7385997772217),
> POINT(-47.3527793884277 -22.7352771759033),
> POINT(-47.3476388888889 -22.7324444444444),
> POINT(-47.3481666666667 -22.7247222222222),
> POINT(-47.2624722222222 -22.7496944444444),
> POINT(-47.34025 -22.7523333333333),
> POINT(-47.3160277777778 -22.7383888888889),
> POINT(-47.3406111111111 -22.76525),
> POINT(-47.3275 -22.7459722222222),
> POINT(-47.3001944444444 -22.7144444444444),
> POINT(-47.3520555555556 -22.7320277777778),
> POINT(-47.2952222222222 -22.7311111111111),
> POINT(-47.3071944444444 -22.7513888888889),
> POINT(-47.2978611111111 -22.7079722222222),
> POINT(-47.3025833333333 -22.7260555555556),
> POINT(-47.3317777777778 -22.7485),
> POINT(-47.2861111111111 -22.7694444444444),
> POINT(-47.2861111111111 -22.7722222222222),
> POINT(-47.2944444444444 -22.775),
> POINT(-47.2861111111111 -22.7805555555556),
> POINT(-47.5083333333333 -22.5055555555556))',4326)))) as ConvexHullCentroid

-- 
Jens Werdin
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