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<p>one process could be:</p>
<ul>
<li>smooth the DTM by a neigbourhood analysis. The width depends
on the size of your convex and concave areas. you can use a mean
filter or lowpass for example</li>
<li>substract the filtered from the original<br>
</li>
<li>select values > or < your cutoff</li>
<li>convert this into polygons</li>
</ul>
<p>see
<a class="moz-txt-link-freetext" href="https://www.researchgate.net/profile/Hazen-Russell/publication/277324326_A_semi-automated_esker_detection_method_EDM_for_improved_quantification_of_glaciated_landscapes/links/5567b6ca08aeab77721eac23/A-semi-automated-esker-detection-method-EDM-for-improved-quantification-of-glaciated-landscapes.pdf">https://www.researchgate.net/profile/Hazen-Russell/publication/277324326_A_semi-automated_esker_detection_method_EDM_for_improved_quantification_of_glaciated_landscapes/links/5567b6ca08aeab77721eac23/A-semi-automated-esker-detection-method-EDM-for-improved-quantification-of-glaciated-landscapes.pdf</a>
for further reading</p>
<p>Hope this helps</p>
<p>Stefan<br>
</p>
<div class="moz-cite-prefix">Am 05.05.2021 um 10:02 schrieb Azzurra
Lentini:<br>
</div>
<blockquote type="cite"
cite="mid:CAJ3Zhxpr3_-kuLzsvmUU_FZwvmH-3oa-6gzDk0cK=yXZfzwfhQ@mail.gmail.com">
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<div class="gmail_default" style="font-family:tahoma,sans-serif">Hi
list,</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">I
need to find the convex and concave areas from a dtm raster
file. Do you have any suggestions? </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Thanks </div>
<div><br>
</div>
-- <br>
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<div dir="ltr">Adjunct Professor University "Roma
Tre"<br>
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<div>Gis Applied for Environmental studies</div>
<div>Risk modelling & Hydrogeology</div>
<div>Consultant DFID-UK, United Nations, EU
projects </div>
<div dir="ltr">AZZURRA LENTINI </div>
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