[postgis-users] st_union(rast) returning null because of non alignment,

Pierre Racine Pierre.Racine at sbf.ulaval.ca
Wed Nov 7 14:40:40 PST 2012

Hi Rhys,

Both rasters must also have their upperlefx and upperlefty on the same grid. 

Could you do:

SELECT ST_AsText(ST_ConvexHull(rast))

on both rasters and post the result here?



> -----Original Message-----
> From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-
> bounces at lists.osgeo.org] On Behalf Of Rhys A.D. Stewart
> Sent: Wednesday, November 07, 2012 5:33 PM
> To: PostGIS Users Discussion
> Subject: [postgis-users] st_union(rast) returning null because of non alignment,
> Greetings,
> according to the trusty docs online two rasters are aligned when they share the
> same skew, scale and srid. Created a raster using st_asraster  and according to
> st_metadata scale, skew and srid are all equal. Howvere st_unon complains
> saying that 'The two rasters provided do not have the same alignment.
> Returning NULL'
> I noticed that  ticket #1336 as possibly relating to my issue, but I'm not entirely
> sure. My posgis version is:
> POSTGIS="2.0.0 r9605" GEOS="3.3.3-CAPI-1.7.4" PROJ="Rel. 4.8.0, 6 March
> 2012" GDAL="GDAL 1.9.0, released 2011/12/29" LIBXML="2.7.8"
> What am I missing or doing incorrectly?
> Regards,
> Rhys

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