<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Hell again:<div><br></div><div>Thanks for the help I followed youre recommendations and use base layer for openstreet map and edited for my needs. None the less I will keep trying to develop this in spatial analysis due that Im working with drone collected data and a lot of areas (whole municipalities) to develop infrastructure maps. </div><div><br></div><div>I will keep posted on progress. Thanks for the help.</div><div><br><div id="AppleMailSignature" dir="ltr"><div style="direction: inherit;">Elvin Roldán</div></div><div dir="ltr"><br>On Apr 18, 2019, at 12:04 PM, Kirk Schmidt <<a href="mailto:kirk@nortekresources.com">kirk@nortekresources.com</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hallo Elvin:</p>
<p>This would be a bit tricky as roads are not created equal. A
paved road and associate paint is very different from a
cobblestone or gravel road. Add shadows from trees, buildings and
rock cuts and the complexity increases. If you used a supervised
classification you would end up with clusters of pixel polygons or
pixel points that would not be very consistent. The level of work
required to edit and simplify these would be very time
consuming. It is for these reasons that original line features
such as roads where digitized as simple vectors. As bernd suggest
below, existing vector data is available for most areas and it is
simply a matter of locating and accessing these sources. <br>
</p>
<p>Kirk <br>
</p>
<div class="moz-cite-prefix">On 4/18/2019 12:10 PM, Bernd
Vogelgesang wrote:<br>
</div>
<blockquote type="cite" cite="mid:93ed973c-3136-28bf-aa4f-0229284e3c3d@gmx.de">
<p>Hi Elvin,</p>
<p>I do not know of any trick how to extract a road network from
images besides a trained image classification model. But may the
question be allowed why you can't just use the OpenStreetMap
data directly?</p>
<p>Cheers,<br>
Bernd<br>
</p>
<div class="moz-cite-prefix">Am 18.04.19 um 15:12 schrieb Elvin
Roldan:<br>
</div>
<blockquote type="cite" cite="mid:000e01d4f5e8$563cccf0$02b666d0$@gmail.com">
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medium)">
<div class="WordSection1">
<p class="MsoNormal">Hello:</p>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal">I’m writing because I’ve been a long
time user QGIS and really appreciate all the work that has
been put to it and all the initiatives to continue to
evolve and maintain it as an important open source GIS
system.</p>
<p class="MsoNormal">My question is aim does anybody know
how to extract a road network using spatial analysis tools
within QGIS. I want to extract all roads from aerial
images to convert to vectors (polylines or polygons) to do
various analysis involving the existing road network.</p>
<p class="MsoNormal">If anybody can point me in the right
direction I would appreciated. </p>
<p class="MsoNormal">Thanks.</p>
<div id="AppleMailSignature">
<div>
<p class="MsoNormal">Elvin Roldán</p>
</div>
</div>
</div>
</div>
<br>
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<pre class="moz-signature" cols="72">--
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: <a class="moz-txt-link-abbreviated" href="mailto:kirk@nortekresources.com">kirk@nortekresources.com</a>
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