[postgis-users] Inconsistency between St_Value and ST_DumpAsPolygons

[dustymugs]

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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