<div dir="ltr">Thank you very much Micha. I only seldom use GRASS, but maybe is the only way.<div>Bye</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Jul 27, 2013 at 10:12 PM, Micha Silver <span dir="ltr"><<a href="mailto:micha@arava.co.il" target="_blank">micha@arava.co.il</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="direction:ltr" bgcolor="#FFFFFF" text="#000000"><div class="im">
<div>On 07/27/2013 10:10 PM, Giacomo
Fontanelli wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Hello everybody
<div><br>
</div>
<div>I would like lo extract the value of each pixel of a raster
below some polygons (of a vector layer).</div>
<div>Better if I could save the result in a text file.</div>
<div>
<br>
</div>
</div>
</blockquote>
<br></div>
You can do this using GRASS. First import both the vector polygons,
and the raster into GRASS:<br>
v.in.ogr <vector polygon.shp> out=polys type=area<br>
r.in.gdal <your raster> out=raster_map<br>
and set the GRASS region to the raster <br>
g.region -p raster_map<br>
THen convert polygons to a raster, and declare it a MASK:<br>
v.to.rast polys out=MASK type=area use=val value=1<br>
<br>
Now run r.out.xyz<br>
r.out.xyz raster_map out=raster_pixels.csv fs=","<br>
<br>
The module r.out.xyz honors the mask, so only those pixels covered
by the mask will be in the output file.<br>
<br>
<br>
<blockquote type="cite"><div class="im">
<div dir="ltr">
<div>The plugin "zonal statistics" does something similar, but
doesn't provide the list of the value of the pixels.</div>
<div><br>
</div>
<div>Does another plugin exist or do I have to make a new one
using python (very hard job for me).</div>
<div><br>
</div>
<div>Thank you very much</div>
</div>
<br></div>
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<br>
<br>
<pre cols="72">--
Micha Silver
GIS Consultant, Arava Development Co.
<a href="http://www.surfaces.co.il" target="_blank">http://www.surfaces.co.il</a></pre>
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