<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>I think that this could also be done as post-processing step:
collapsing lines that are really close-by a discontinuity on the
discontinuity (snap).</p>
<p>I was thinking about using the borders I introduced to close
contours (no data zones and raster edges) to handle those
discontinuities, but I don't think it will look good.</p>
<p>Another think I'd like to explore is contour simplification to
avoid the huge number of points caused by the marching squares.
I'm well aware of the complexity of the problem, but it's an
interesting one ;-)<br>
</p>
<br>
<div class="moz-cite-prefix">Le 22/10/2017 à 15:06, Roberto Ribeiro
a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CANTZQ+x84PGWW8xjimjQo8X5QpamMSq-tOUxTbHJM8mA6S07=A@mail.gmail.com">
<div dir="ltr">In cases of cliffs and such (i.e. sudden drops in
altitude), traditional photogrammetric softwares like PCI and
Erdas work with break lines, as in, you literally draw a line
along edges you want computed discontinuously. That is not
really practical to do in command-line GDAL, though you could
import a previously created line vector and tell the algorithm
to process with those in mind. <br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2017-10-20 16:18 GMT-02:00 Andrew C
Aitchison <span dir="ltr"><<a
href="mailto:andrew@aitchison.me.uk" target="_blank"
moz-do-not-send="true">andrew@aitchison.me.uk</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">On Fri, 20
Oct 2017, Vincent Mora wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
I'll also try the gdal_polygonize approach, but I don't
think it's the<br>
same thingl: with raster-classif + gdal_polygonize, if you
have 3<br>
classes 1,2,3 polygons from 1 can touch a polygon from 3,
with contour<br>
lines there will always be a polygon of class 2 in
between.<br>
<br>
Or am I missing something.<br>
<br>
If someone believes I'm doing something useless and/or
stupid (that also<br>
happens), please do tell.<br>
</blockquote>
<br>
Can you polygonize contours across a vertical cliff ?<br>
If so, 2 may be "between" 1 and 3, but at some points they
may all touch.<br>
<br>
On some maps, contours become discontinuous around cliffs
and quarries.<span class="HOEnZb"><font color="#888888"><br>
<br>
-- <br>
Andrew C Aitchison</font></span>
<div class="HOEnZb">
<div class="h5"><br>
<br>
______________________________<wbr>_________________<br>
gdal-dev mailing list<br>
<a href="mailto:gdal-dev@lists.osgeo.org"
target="_blank" moz-do-not-send="true">gdal-dev@lists.osgeo.org</a><br>
<a
href="https://lists.osgeo.org/mailman/listinfo/gdal-dev"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://lists.osgeo.org/mailma<wbr>n/listinfo/gdal-dev</a></div>
</div>
</blockquote>
</div>
<br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
gdal-dev mailing list
<a class="moz-txt-link-abbreviated" href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a>
<a class="moz-txt-link-freetext" href="https://lists.osgeo.org/mailman/listinfo/gdal-dev">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a></pre>
</blockquote>
<br>
</body>
</html>