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On 03/17/2012 01:57 AM, Rich Shepard wrote:
<blockquote
cite="mid:alpine.LNX.2.00.1203161650250.2789@salmo.appl-ecosys.com"
type="cite"> Two source DEMs each cover half the project
analytical area. I want to
<br>
join the two into a single raster DEM. Tried using 'r.mapcalc
dem_proj =
<br>
dem2 + dem3' but that did not produce anything visible. From
reading
<br>
</blockquote>
<br>
I think that the '+'operator honors NULL cells, so anywhere that is
NULL in either raster will be null in the result. That's not what
you want in this case.<br>
<br>
<blockquote
cite="mid:alpine.LNX.2.00.1203161650250.2789@salmo.appl-ecosys.com"
type="cite">mapcalc.pdf and mapcalc-algebra.pdf I know the module
is designed for
<br>
combining multiple raster maps cell-by-cell. I've not found how to
<br>
edge-match and join two rasters that do not have overlapping
coverage.
<br>
<br>
Please pass me a pointer to the appropriate module to use for
this
<br>
operation.
<br>
<br>
</blockquote>
<br>
r.patch does this.<br>
As per the man page, be sure to set the region to *all* input
rasters in advance:<br>
g.region rast=dem2,dem3<br>
<br>
<blockquote
cite="mid:alpine.LNX.2.00.1203161650250.2789@salmo.appl-ecosys.com"
type="cite">TIA,
<br>
<br>
Rich
<br>
<br>
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</blockquote>
<p><br>
</p>
<br>
<pre class="moz-signature" cols="72">--
Micha Silver
GIS Consultant, Arava Development Co.
<a class="moz-txt-link-freetext" href="http://www.surfaces.co.il">http://www.surfaces.co.il</a></pre>
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