[postgis-users] Finding highest cell value in raster using ST_Value

[Bborie Park]

Too many columns.  I was thinking that this is better served in a
separate function as that value could be repeated.  I'm adding a ticket
for that separate function.

On 06/25/2012 01:36 PM, Pierre Racine wrote:
> Good find Bborie!
> 
> I would add that we should fill a ticket like "ST_Summary should report the x and y raster coordinates of the max and the min". So four new columns...
> 
> Pierre
> 
>> -----Original Message-----
>> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
>> bounces at postgis.refractions.net] On Behalf Of Bborie Park
>> Sent: Monday, June 25, 2012 4:32 PM
>> To: postgis-users at postgis.refractions.net
>> Subject: Re: [postgis-users] Finding highest cell value in raster using ST_Value
>>
>> Egge-Jan,
>>
>> That is an intriguing question with no clean/simple solution.  The
>> fastest approach may be to call ST_Reclass() to create a 1BB mask based
>> upon that value and the pass the resulting raster to
>> ST_PixelAsPolygons() which will give you what you want.
>>
>> Yes, the above is a round-about way to do this.  This is something I'll
>> (ST_PixelofValue?) see about adding for PostGIS 2.1.
>>
>> -bborie
>>
>> On 06/25/2012 01:16 PM, e.j.h.polle wrote:
>>> Hi,
>>>
>>> OK - with ST_SummaryStats it is easy to retrieve the highest value in the
>>> raster, but then I only have this value. Now I want to retrieve
>>> (information about) the cell/pixel having this value, to be able to
>>> visualize the highest point on the map. My original query (see first post)
>>> does give me this information (after 45 seconds...).
>>>
>>> How would I go about to get hold of the pixel with the highest value,
>>> knowing this value?
>>>
>>> Cheers,
>>>
>>> Egge-Jan
>>>
>>> On Sunday, June 24, 2012 8:47:58 PM UTC+1, DavidRA wrote:
>>>>
>>>> Why don't you use ST_SummaryStats instead ST_Value? That way you can get
>>>> easily any basic stat, included the maximum value of the raster. It would
>>>> be
>>>> something like:
>>>>
>>>> SELECT (ST_SummaryStats(rast)).max FROM raster_table;
>>>>
>>>> --
>>>> View this message in context:
>>>> http://postgis.17.n6.nabble.com/Finding-highest-cell-value-in-raster-using-
>> ST-Value-tp4998545p4998554.html
>>>> Sent from the PostGIS - User mailing list archive at Nabble.com.
>>>> _______________________________________________
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>>>>
>>>
>>> On Sunday, June 24, 2012 8:47:58 PM UTC+1, DavidRA wrote:
>>>>
>>>> Why don't you use ST_SummaryStats instead ST_Value? That way you can get
>>>> easily any basic stat, included the maximum value of the raster. It would
>>>> be
>>>> something like:
>>>>
>>>> SELECT (ST_SummaryStats(rast)).max FROM raster_table;
>>>>
>>>> --
>>>> View this message in context:
>>>> http://postgis.17.n6.nabble.com/Finding-highest-cell-value-in-raster-using-
>> ST-Value-tp4998545p4998554.html
>>>> Sent from the PostGIS - User mailing list archive at Nabble.com.
>>>> _______________________________________________
>>>> postgis-users mailing list
>>>> postgis-users at postgis.refractions.net
>>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>>
>>>
>>> On Sunday, June 24, 2012 8:47:58 PM UTC+1, DavidRA wrote:
>>>>
>>>> Why don't you use ST_SummaryStats instead ST_Value? That way you can get
>>>> easily any basic stat, included the maximum value of the raster. It would
>>>> be
>>>> something like:
>>>>
>>>> SELECT (ST_SummaryStats(rast)).max FROM raster_table;
>>>>
>>>> --
>>>> View this message in context:
>>>> http://postgis.17.n6.nabble.com/Finding-highest-cell-value-in-raster-using-
>> ST-Value-tp4998545p4998554.html
>>>> Sent from the PostGIS - User mailing list archive at Nabble.com.
>>>> _______________________________________________
>>>> postgis-users mailing list
>>>> postgis-users at postgis.refractions.net
>>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>>
>>>
>>>
>>>
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>>
>> --
>> Bborie Park
>> Programmer
>> Center for Vectorborne Diseases
>> UC Davis
>> 530-752-8380
>> bkpark at ucdavis.edu
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-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu