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List: postgis-users
Subject: Re: [postgis-users] Raster calculation on 3d raster (stack)
From: Pierre Racine <Pierre.Racine () sbf ! ulaval ! ca>
Date: 2015-11-20 13:23:43
Message-ID: e910072b38bb4fd79e6ba264c5737cc9 () ul-exc-pr-mbx13 ! ulaval ! ca
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Doesn't the second example (One raster, several bands) similar to your case in the \
doc?
http://postgis.net/docs/RT_ST_MapAlgebra.html
Pierre
From: postgis-users [mailto:postgis-users-bounces@lists.osgeo.org] On Behalf Of David \
Haynes
Sent: Tuesday, November 17, 2015 9:48 AM
To: postgis-users@lists.osgeo.org
Subject: [postgis-users] Raster calculation on 3d raster (stack)
Hello,
I have a mulibanded raster and I am wondering if I can apply any of the raster \
processing functions (min, max, mean, stdev) to multibanded rasters. Specifically, I \
am wondering if these functions will be able to applied to the z-axis.
Here is an example, I have worked up in python starting with two 2d arrays.
x = [[1,4,5,6], [3,5,6,2]]
z = [[2,7,8,9], [8,3,5,9]]
convert to np.array
y = np.dstack((np.array(x), np.array(z)))
> > > y.sum(2)
array([[ 3, 11, 13, 15],
[11, 8, 11, 11]])
I want to apply the raster processing functions to the z-axis and I am wondering if I \
can do it in PostGIS? It seems like the mapalgebra call back functions could do this, \
but I am having difficulty finding an example.
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<p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Doesn't \
the second example (One raster, several bands) similar to your case in the \
doc?<o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><a \
href="http://postgis.net/docs/RT_ST_MapAlgebra.html">http://postgis.net/docs/RT_ST_MapAlgebra.html</a><o:p></o:p></span></p>
<p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Pierre<o:p></o:p></span></p>
<p class="MsoNormal"><span \
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<p class="MsoNormal"><b><span \
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span \
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> \
postgis-users [mailto:postgis-users-bounces@lists.osgeo.org] <b>On Behalf Of \
</b>David Haynes<br> <b>Sent:</b> Tuesday, November 17, 2015 9:48 AM<br>
<b>To:</b> postgis-users@lists.osgeo.org<br>
<b>Subject:</b> [postgis-users] Raster calculation on 3d raster \
(stack)<o:p></o:p></span></p> </div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Hello,<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I have a mulibanded raster and I am wondering if I can apply any \
of the raster processing functions (min, max, mean, stdev) to multibanded rasters. \
Specifically, I am wondering if these functions will be able to applied to the \
z-axis. <o:p></o:p></p> </div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Here is an example, I have worked up in python starting with two \
2d arrays.<o:p></o:p></p> </div>
<div>
<p class="MsoNormal">x = [[1,4,5,6], [3,5,6,2]]<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">z = [[2,7,8,9], [8,3,5,9]]<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">convert to np.array<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">y = np.dstack((np.array(x), np.array(z)))<o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal">>>> y.sum(2)<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">array([[ 3, 11, 13, 15],<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> [11, 8, 11, \
11]])<o:p></o:p></p> </div>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I want to apply the raster processing functions to the z-axis \
and I am wondering if I can do it in PostGIS? It seems like the mapalgebra call back \
functions could do this, but I am having difficulty finding an \
example.<o:p></o:p></p> </div>
</div>
</div>
</div>
</body>
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