[Qgis-user] Inflection point of a terrain

[Jonathan Aguero Valverde]

Dear Patrick,

If you have Qgis with GRASS you can use r.geomorphon.

https://grass.osgeo.org/grass76/manuals/addons/r.geomorphon.html

I just ran a test in a DEM in QGIS 3.10 and GRASS 7.6 and it worked 
perfectly.

The image presents the geomorphons estimated:

source: grass 7.6 manual.

The resulting maps looks like this:


Hope this helps.

Jonathan.


El 31/10/2019 a las 02:52, Patrick Marx escribió:
> Hi all,
> I would like to find the contour line in a dem at the inflection point 
> of the slope. I mean, I would like to know at which height the terrain 
> is changing from convex to concave. I found plugins which calculate if 
> a specific cell is convex or concave in relation to its neighbours in 
> a 3 x 3 raster. But I would like to know it for a specific terrain.
> Does anyone has an idea?
> Regards Patrick
>
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-- 
Ing. Jonathan Agüero Valverde, Ph.D.
Profesor e Investigador
Programa de Investigación en Desarrollo Urbano Sostenible  (ProDUS)
Escuela de Ingeniería Civil
Universidad de Costa Rica
Tel: (506) 2511-2787, 2511-2777
jonathan.aguero at ucr.ac.cr

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