[postgis-users] ST_Clip
Pierre Racine
Pierre.Racine at sbf.ulaval.ca
Thu Jul 26 10:39:45 PDT 2012
What happen if do a query like this:
SELECT (gv).geom, (gv).val
FROM (SELECT ST_PixelAsPolygons(ST_AsRaster(ST_Buffer(ST_Centroid(ST_Envelope(rast)), 0.5000), rast, ST_BandPixelType(rast, 1), 1, -1)) gv
FROM hdr
WHERE rid = 4
) foo
and display the resulting geometries labelled with the values?
This is the first step of the clipping: creating a rasterized version of the buffer geometry aligned on the raster.
Pierre
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> bounces at postgis.refractions.net] On Behalf Of Paolo Cavallini
> Sent: Thursday, July 26, 2012 10:53 AM
> To: postgis-users at postgis.refractions.net
> Subject: Re: [postgis-users] ST_Clip
>
> Il 26/07/2012 16:33, Pierre Racine ha scritto:
> > So the big square, in your image, is a whole 64x64 tile?
> not; I tried with a smaller buffer, I obtained a smaller square.
> > I gave a try to the same kind of query here and everything is fine. Are you sure
> the circle is the same geometry used to clip?
> it should be: I relaunched the same command, just removing the ST_Clip
> > What about SELECT ST_PostGIS_Full_Version()
> SELECT ST_PostGIS_Full_Version();
> ERROR: function st_postgis_full_version() does not exist
>
> SELECT PostGIS_Full_Version();
> POSTGIS="2.0.1 r9979" GEOS="3.3.3-CAPI-1.7.4" PROJ="Rel. 4.7.1, 23
> September 2009" GDAL="GDAL 1.9.0, released 2011/12/29" LIBXML="2.8.0"
> RASTER
>
> Thanks a lot.
>
> --
> Paolo Cavallini - Faunalia
> www.faunalia.eu
> Full contact details at www.faunalia.eu/pc
> Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario
>
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