<div dir="ltr">Hi there,<div><br></div><div>greetings;</div><div>I have seen and done such things, a lot,</div><div>and I would like to give you a message of caution about it.</div><div><br></div><div>One serious problem is here that it includes error inconsistencies (sheet edges vs sheet centers),</div><div>another one is about classes and patches that are incorrect to start with (all sheets; merged or not).</div><div><br></div><div>In other words,</div><div>there are several types of errors in such 'technical artefacts' aka merged forest patch maps; </div><div>they "cannot be used for navigation", to put it politely.</div><div>It's a blurr of things, and a major problem with forest maps and forest inventory maps out there.</div><div><br></div><div>I know of forest maps and regions that have accuracies of 40%, if ground-truthed.<br>So yes, they look great on the screen and in GIS but are close to random (50% accuracy)</div><div>if ever used and interpreted for applications.</div><div>Please be aware; happy to hear about a fix; beyond technical GIS ones, or rubber sheeting.</div><div><br></div><div>Keep me posted please; thanks.</div><div>Very best</div><div> Falk</div><div><br></div><div>PS There is currently no single accepted map of global forest cover;</div><div>FAO, IUFRO etc cannot really agree on such details whatsoever.</div><div>And yes, Remote Sensing products, LIDAR and air photo interpretation</div><div>can be rather poor for quality, usually they are.</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, May 6, 2020 at 2:50 PM Michael Harte <<a href="mailto:mharte@ozemail.com.au">mharte@ozemail.com.au</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
Reiko,<br>
<br>
You could try something like this:<br>
<br>
<ol>
<li>Merge all forests into a single file (if you haven't already);</li>
<li>Create a new field in the forests table called something like
"border"</li>
<li>Create lines that trace the panel boundaries, that separate
the forests you want to join;</li>
<li>Buffer each of those lines by some small distance (try 1
meter);</li>
<li>For each buffer "Select by location" all features in forests
that intersect buffer;</li>
<li>Use the field calculator in the table to enter a unique
identifier for the selected features in the "border" field;</li>
<li>Do this for each buffer;</li>
<li>Dissolve the forest layer on the border field.</li>
</ol>
<p>Feel free to get in touch.</p>
<p>Cheers,</p>
<p>Mike<br>
</p>
<br>
<br>
<br>
<pre>Message: 1
Date: Wed, 6 May 2020 14:55:30 -0400
From: RMG <a href="mailto:reikogoodwin@gmail.com" target="_blank"><reikogoodwin@gmail.com></a>
To: <a href="mailto:qgis-user@lists.osgeo.org" target="_blank">qgis-user@lists.osgeo.org</a>
Subject: [Qgis-user] combining fragmented forests
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<a href="mailto:CALwVOrJq9njBAdtvVeXLVsVT8SEjcDfp5mp=AYdoOi93w3TWxA@mail.gmail.com" target="_blank"><CALwVOrJq9njBAdtvVeXLVsVT8SEjcDfp5mp=AYdoOi93w3TWxA@mail.gmail.com></a>
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Hello,
I have five shapefiles that contain thousands of fragmented forests that I
created from a NDVI raster of a large protected area in West Africa, which
I separated into five panels. Now, how do I stitch thousands of the
fragmented forests at the borders?
Each shapefile's attributes have ID, count (number of units), area, and
perimeter, so I can visually recognize which fragments need stitching, but
because there are so many, I don't think I can do it manually.
Any help would be appreciated.
Best wishes,
Reiko Matsuda Goodwin
Comoé Monkey Project <a href="https://www.facebook.com/ComoeMonkeyProject/" target="_blank"><https://www.facebook.com/ComoeMonkeyProject/></a>
Guenon Conservation Community
<a href="http://facebook.com/GuenonConservationCommunity/" target="_blank"><http://facebook.com/GuenonConservationCommunity/></a>
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