Oh the joys of mailing lists!!!<div><br></div><div>Thanks Pierre, exactly what was required.</div><div>All the best,</div><div><br></div><div>Rhys</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Nov 8, 2012 at 11:44 AM, Pierre Racine <span dir="ltr"><<a href="mailto:Pierre.Racine@sbf.ulaval.ca" target="_blank">Pierre.Racine@sbf.ulaval.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">So displaying the two extents it is clear that the two rasters are not aligned on the same grid. You will have to ST_SnapToGrid() one raster to the other before ST_Union()ing them.<br>
<div class="im HOEnZb"><br>
Pierre<br>
<br>
> -----Original Message-----<br>
> From: <a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:postgis-users-">postgis-users-</a><br>
> <a href="mailto:bounces@lists.osgeo.org">bounces@lists.osgeo.org</a>] On Behalf Of Rhys A.D. Stewart<br>
</div><div class="im HOEnZb">> Sent: Thursday, November 08, 2012 6:50 AM<br>
> To: PostGIS Users Discussion<br>
> Subject: Re: [postgis-users] st_union(rast) returning null because of non<br>
> alignment,<br>
><br>
</div><div class="HOEnZb"><div class="h5">> So given that st_union is not the solution, how would I go about merging two<br>
> adjacent raster tiles?<br>
><br>
><br>
> On Wed, Nov 7, 2012 at 6:12 PM, Rhys A.D. Stewart <<a href="mailto:rhys.stewart@gmail.com">rhys.stewart@gmail.com</a>><br>
> wrote:<br>
><br>
><br>
> ok, well that may be the issue, I was trying to union a rasterised table of<br>
> adjacent polygons. So will the corners may touch I doubt they overlap, but here<br>
> is the output of st_metadata for two of the polygons that are adjacent:<br>
><br>
> Clarendon 698486.043582936 617384.893096908 153 229 250 250 0 0<br>
> 3448 4<br>
> Manchester 683177.872077352 632613.85425893 117 182 250 250 0 0<br>
> 3448 4<br>
><br>
><br>
><br>
> On Wed, Nov 7, 2012 at 6:01 PM, Pierre Racine<br>
> <<a href="mailto:Pierre.Racine@sbf.ulaval.ca">Pierre.Racine@sbf.ulaval.ca</a>> wrote:<br>
><br>
><br>
> By "on the same grid" I mean " at least one of any of the four<br>
> corners of any pixel of one raster falls on any corner of the grid of the other<br>
> raster" as stated in the ST_SameAlignment() doc.<br>
><br>
> What is (are) the pixel size?<br>
><br>
><br>
> > -----Original Message-----<br>
> > From: <a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:postgis-">postgis-</a><br>
> users-<br>
> > <a href="mailto:bounces@lists.osgeo.org">bounces@lists.osgeo.org</a>] On Behalf Of Rhys A.D. Stewart<br>
><br>
> > Sent: Wednesday, November 07, 2012 5:51 PM<br>
> > To: PostGIS Users Discussion<br>
><br>
> > Subject: Re: [postgis-users] st_union(rast) returning null<br>
> because of non<br>
> > alignment,<br>
> ><br>
> > Pierre,<br>
> ><br>
> > If by on the same grid you mean equal, then no hey are not.<br>
> Here they are.<br>
> ><br>
> ><br>
> > 1: POLYGON((766242.610093044<br>
> 641994.463110607,779742.610093044<br>
> > 641994.463110607,779742.610093044<br>
> 648494.463110607,766242.610093044<br>
> > 648494.463110607,766242.610093044 641994.463110607))<br>
> > 2:POLYGON((698486.043582936<br>
> 617384.893096908,736736.043582936<br>
> > 617384.893096908,736736.043582936<br>
> 674634.893096908,698486.043582936<br>
> > 674634.893096908,698486.043582936 617384.893096908))<br>
> ><br>
> > Thanks,<br>
> ><br>
> > Rhys<br>
> ><br>
> ><br>
> > On Wed, Nov 7, 2012 at 5:40 PM, Pierre Racine<br>
> <<a href="mailto:Pierre.Racine@sbf.ulaval.ca">Pierre.Racine@sbf.ulaval.ca</a>><br>
> > wrote:<br>
> ><br>
> ><br>
> > Hi Rhys,<br>
> ><br>
> > Both rasters must also have their upperlefx and upperlefty<br>
> on the same<br>
> > grid.<br>
> ><br>
> > Could you do:<br>
> ><br>
> > SELECT ST_AsText(ST_ConvexHull(rast))<br>
> ><br>
> > on both rasters and post the result here?<br>
> ><br>
> > Thanks,<br>
> ><br>
> > Pierre<br>
> ><br>
> ><br>
> > > -----Original Message-----<br>
> > > From: <a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a><br>
> [mailto:<a href="mailto:postgis-users-">postgis-users-</a><br>
> > > <a href="mailto:bounces@lists.osgeo.org">bounces@lists.osgeo.org</a>] On Behalf Of Rhys A.D.<br>
> Stewart<br>
> > > Sent: Wednesday, November 07, 2012 5:33 PM<br>
> > > To: PostGIS Users Discussion<br>
> > > Subject: [postgis-users] st_union(rast) returning null<br>
> because of non<br>
> > alignment,<br>
> > ><br>
> > > Greetings,<br>
> > ><br>
> > > according to the trusty docs online two rasters are<br>
> aligned when they<br>
> > share the<br>
> > > same skew, scale and srid. Created a raster using<br>
> st_asraster and<br>
> > according to<br>
> > > st_metadata scale, skew and srid are all equal. Howvere<br>
> st_unon<br>
> > complains<br>
> > > saying that 'The two rasters provided do not have the<br>
> same alignment.<br>
> > > Returning NULL'<br>
> > ><br>
> > > I noticed that ticket #1336 as possibly relating to my<br>
> issue, but I'm not<br>
> > entirely<br>
> > > sure. My posgis version is:<br>
> > > POSTGIS="2.0.0 r9605" GEOS="3.3.3-CAPI-1.7.4"<br>
> PROJ="Rel. 4.8.0, 6<br>
> > March<br>
> > > 2012" GDAL="GDAL 1.9.0, released 2011/12/29"<br>
> LIBXML="2.7.8"<br>
> > > LIBJSON="UNKNOWN" TOPOLOGY RASTER<br>
> > ><br>
> > ><br>
> > > What am I missing or doing incorrectly?<br>
> > ><br>
> > > Regards,<br>
> > ><br>
> > > Rhys<br>
> ><br>
> > _______________________________________________<br>
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> ><br>
> ><br>
><br>
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