How we get raster values

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How we get raster values

orkun
 Hello,

How can we get raster values of a map that intersects with certian part of a polygon map ?

 regards

--
Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem  Dairesi Başkanlığı-CBS Grubu


________________________

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency

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Re: How we get raster values

TomvanTilburg
Hi Ahmet,

It depends on how you would like to have the values returned.
If it's an average (or some other kind of statistics) I think you need a two step approach:

1) Clip the raster where it intersects with the polygon:
    http://postgis.net/docs/RT_ST_Clip.html

2) Do you stats on the resulting clipped image:
    http://postgis.net/docs/RT_ST_SummaryStats.html

Hope this helps,
    Tom

On 7/27/2015 4:16 PM, Ahmet Temiz wrote:
 Hello,

How can we get raster values of a map that intersects with certian part of a polygon map ?

 regards

--
Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem  Dairesi Başkanlığı-CBS Grubu


________________________

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency


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Re: How we get raster values

Kishore raju
I am trying to get pixels intersected in raster layer with polygons in vector layer. can you please help me in designing the query.

On Wed, Jul 29, 2015 at 5:26 PM, Tom van Tilburg <[hidden email]> wrote:
Hi Ahmet,

It depends on how you would like to have the values returned.
If it's an average (or some other kind of statistics) I think you need a two step approach:

1) Clip the raster where it intersects with the polygon:
    http://postgis.net/docs/RT_ST_Clip.html

2) Do you stats on the resulting clipped image:
    http://postgis.net/docs/RT_ST_SummaryStats.html

Hope this helps,
    Tom


On 7/27/2015 4:16 PM, Ahmet Temiz wrote:
 Hello,

How can we get raster values of a map that intersects with certian part of a polygon map ?

 regards

--
Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem  Dairesi Başkanlığı-CBS Grubu


________________________

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency


_______________________________________________
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[hidden email]
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--
with regards

K. Kishore Raju
                BE, ME,M.Tech,(Ph.D).
Asst. Professor IT Dept,
S.R.K.R Engg. College,
Bhimavaram, W.G.Dt
AP,India-534202
Contact No: 09949844004

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Re: How we get raster values

TomvanTilburg
Ahmet,

I think it is about the same question as I earlier answered for Juli. I'm copy pasting it here, hope it helps:
You have to adapt it to your own circumstances ofcourse, but at the same time I'd encourage you to read the documentation because it has samples included.
---------------
Try to split your functionality with the help of 'WITH' statements and see if you can do the grouping in that way in a subselect.
Something like:

WITH clips AS (
    SELECT p.ecoregion_cod, ST_Union(ST_Clip(r.rast,1, p.geom, true)) AS rast
    FROM gis_wd.wd_ecoregiones AS p, rastertmp.prova AS r
    WHERE ST_Intersects(r.rast, p.geom)
    GROUP BY ecoregion_cod --now you don't have to group by the raster result itself
)
SELECT p.ecoregion_co, (ST_SummaryStats(rast, 1)).* FROM clips --this should give you the stats per ecoregion_co

---------------------------

Best,
 Tom

On 7/31/2015 6:35 PM, Kishore raju wrote:
I am trying to get pixels intersected in raster layer with polygons in vector layer. can you please help me in designing the query.

On Wed, Jul 29, 2015 at 5:26 PM, Tom van Tilburg <[hidden email]> wrote:
Hi Ahmet,

It depends on how you would like to have the values returned.
If it's an average (or some other kind of statistics) I think you need a two step approach:

1) Clip the raster where it intersects with the polygon:
    http://postgis.net/docs/RT_ST_Clip.html

2) Do you stats on the resulting clipped image:
    http://postgis.net/docs/RT_ST_SummaryStats.html

Hope this helps,
    Tom


On 7/27/2015 4:16 PM, Ahmet Temiz wrote:
 Hello,

How can we get raster values of a map that intersects with certian part of a polygon map ?

 regards

--
Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem  Dairesi Başkanlığı-CBS Grubu


________________________

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency


_______________________________________________
postgis-users mailing list
[hidden email]
http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users


_______________________________________________
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[hidden email]
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--
with regards

K. Kishore Raju
                BE, ME,M.Tech,(Ph.D).
Asst. Professor IT Dept,
S.R.K.R Engg. College,
Bhimavaram, W.G.Dt
AP,India-534202
Contact No: 09949844004


_______________________________________________
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[hidden email]
http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users


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