[postgis-users] Inconsistency between St_Value and ST_DumpAsPolygons

[Jean Marchal]

I am using GDAL 1.9.2, yep ST_PixelAsPolygons() works fine,

Jean

2013/6/6 dustymugs <dustymugs at gmail.com>

> What version of GDAL are you using? ST_DumpAsPolygons() uses GDAL for
> processing. I notice that ST_PixelAsPolygons() works correctly...
>
> -bborie
>
> On 06/06/2013 01:04 PM, Jean Marchal wrote:
> > Bborie,
> >
> > I used ST_Value to prove that the value for pixel with coordinates (8,2)
> > does exist. I did not mention it but adjacent pixels contains different
> > values (see reproducible example).
> >
> > Jean
> >
> > 2013/6/6 Bborie Park <dustymugs at gmail.com>
> >
> >> ST_Value and ST_DumpAsPolygons do very different things. ST_Value gets a
> >> value for a specific pixel while ST_DumpAsPolygons() dumps values by
> >> merging pixels with same value in an area.
> >>
> >> -bborie
> >>
> >>
> >> On Thu, Jun 6, 2013 at 12:38 PM, Jean Marchal <jean.d.marchal at gmail.com
> >wrote:
> >>
> >>> Dear List,
> >>>
> >>> value's number 4 in this raster come out with ST_Value:
> >>>
> >>> SELECT ST_Value(rast, 1, 8, 2), ST_BandnoDataValue(rast),
> >>> ST_BandPixelType(rast)
> >>> FROM (SELECT '
> >>>
> 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'::raster
> >>> rast) foo
> >>>
> >>> but not with ST_DumpAsPolygons:
> >>>
> >>> SELECT (ST_DumpAsPolygons(rast)).val
> >>> FROM (SELECT
> >>>
> '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'::raster
> >>> rast) foo
> >>>
> >>> Is this a bug or I am doing something wrong ?
> >>>
> >>> Thanks,
> >>>
> >>> Jean
> >>>
> >>> --
> >>> Jean Marchal
> >>>
> >>> Etudiant au doctorat / PHD student
> >>> Université Laval - Pavillon Abitibi-Price
> >>> Faculté de foresterie, de géographie et de géomatique
> >>> 2405, rue de la Terrasse
> >>> Québec (Québec) G1V 0A6
> >>>
> >>> _______________________________________________
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> >>>
> >>>
> >>
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> >>
> >>
> >
> >
> >
> >
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-- 
Jean Marchal

Etudiant au doctorat / PHD student
Université Laval - Pavillon Abitibi-Price
Faculté de foresterie, de géographie et de géomatique
2405, rue de la Terrasse
Québec (Québec) G1V 0A6
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