[postgis-tickets] [PostGIS] #3483: Problem with ST_Union

[PostGIS]

#3483: Problem with ST_Union
-----------------------------------------+---------------------------
 Reporter:  krzysiek                     |      Owner:  pramsey
     Type:  defect                       |     Status:  new
 Priority:  medium                       |  Milestone:  PostGIS 2.1.9
Component:  postgis                      |    Version:  2.1.x
 Keywords:  ST_Union, raster, alignment  |
-----------------------------------------+---------------------------
 I have loaded some rasters into Postgis. I did a lot of ST_XXXX (scale,
 snap to grid,resample) magic to make them aligned. After executing:

 select
 r1.rid,r2.rid
 ,ST_NotSameAlignmentReason(r1.rast,r2.rast)
 ,ST_SameAlignment(r1.rast,r2.rast)
 from
   rasters.r r1,
   rasters.r r2
 where not ST_SameAlignment(r1.rast,r2.rast)

 I got nothing, if I remove:

     where not ST_SameAlignment(r1.rast,r2.rast)

 all I got is

     "The rasters are aligned"

 Which seems ok, but when I execute:

 SELECT ST_Union(rast,'FIRST') from rasters.r

 I got:

     rt_raster_from_two_rasters: The two rasters provided do not have the
 same alignment

 Why ?

 Postgres 9.4

 "POSTGIS="2.1.8 r13780" GEOS="3.5.0-CAPI-1.9.0 r4090" PROJ="Rel. 4.8.0, 6
 March 2012" GDAL="GDAL 1.11.1, released 2014/09/24" LIBXML="2.7.8"
 LIBJSON="UNKNOWN" RASTER"

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/3483>
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