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<div class="moz-cite-prefix">On 28/02/2020 2:12, ming han wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAD+uAWh7av3nbaoyH75TzG5Sg=DFoVK-T31ZBaR+KnrZZGLnCg@mail.gmail.com">
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<div dir="ltr">Hi all
<div> </div>
<div> Is qgis has a function like "stream link" in Arcgis
which can convert the stream raster to feature. </div>
<div> I tried with raster to vector function in grass and
qgis. it has following errors. </div>
<div><br>
</div>
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</blockquote>
<p>Using GRASS, the way to do this involves two steps: <br>
</p>
<p>first you want to "thin" the raster streams using the module
"r.thin". This insures that there will not be adjacent pixels. <br>
</p>
<p>Then, when you convert to stream lines, specify the type as line
feature.</p>
<p>So here are the commands (if you have a raster stream network
called "streams"):</p>
<p><br>
</p>
<p><font size="+1"><tt>r.thin streams output=streams_thin</tt></font></p>
<p><font size="+1"><tt>r.to.vect streams_thin output=streams_vector
type=line</tt></font></p>
<p><br>
</p>
<p>In addition, I should mention that GRASS offers a set of plugins
for hydrology: r.stream.*. Among them is the module <font
size="+1"><tt>r.stream.order</tt></font>.<tt> </tt>Using this
plugin you can create a stream vector directly from the flow
direction and flow accumulation grids, and you get the stream
order and upstream flow accumulation area "for free".</p>
<p><br>
</p>
<p>HTH</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:CAD+uAWh7av3nbaoyH75TzG5Sg=DFoVK-T31ZBaR+KnrZZGLnCg@mail.gmail.com">
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<div>Cheers</div>
<div>Ming</div>
<div><br>
</div>
<div>
<div><img src="cid:part1.4BCFB068.6FC67549@gmail.com"
alt="image.png" class="" width="463" height="300"><br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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<pre class="moz-signature" cols="72">--
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
<a class="moz-txt-link-freetext" href="https://orcid.org/0000-0002-1128-1325">https://orcid.org/0000-0002-1128-1325</a></pre>
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