subject:"\[Qgis\-user\] convex and concave areas"

Re: [Qgis-user] convex and concave areas

2021-05-05 Thread Azzurra Lentini

Hi Stefan and Sebastian, thanks a lot for your suggestions.
Azzurra

Il mer 5 mag 2021, 15:30 Sebastian Gutwein  ha scritto:

> In the QGIS toolbox there is a Saga algorithm called Terrain Surface
> Convexity that does calculate convexity or concavity. I have never used it.
> http://www.saga-gis.org/saga_tool_doc/2.2.3/ta_morphometry_21.html
> https://sourceforge.net/p/saga-gis/discussion/354013/thread/3fadd3e7/
>
> On Wed, May 5, 2021 at 4:14 AM Stefan Giese (WhereGroup) <
> stefan.gi...@wheregroup.com> wrote:
>
>> one process could be:
>>
>>- 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
>>- substract the filtered from the original
>>- select values > or < your cutoff
>>- convert this into polygons
>>
>> see
>> 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
>> for further reading
>>
>> Hope this helps
>>
>> Stefan
>> Am 05.05.2021 um 10:02 schrieb Azzurra Lentini:
>>
>> Hi list,
>> I need to find the convex and concave areas from a dtm raster file. Do
>> you have any suggestions?
>> Thanks
>>
>> --
>> Adjunct Professor University "Roma Tre"
>> Gis Applied for Environmental studies
>> Risk modelling & Hydrogeology
>> Consultant DFID-UK, United Nations, EU projects
>> AZZURRA LENTINI
>> ++
>> Italy Mobile Tel.: **(39) 338 24 40 676
>> ++
>> SKYPE azzurrahydro
>> ++
>>
>> *azzurralent...@gmail.com *
>>
>> *azzurra.lent...@uniroma3.it  *
>> ++
>> *Par respect pour l'environnement,*
>>
>> *n'imprimez ce mail qu'en cas d'absolue nécessité*
>>
>>
>>
>>
>>
>>
>> ___
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>>
>> --
>> Mit freundlichen Grüßen
>> Stefan Giese
>> Projektleiter/Consultant
>> 
>> Aufwind durch Wissen!
>> Web-Seminare und Online-Schulungen
>> bei der www.foss-academy.com
>> 
>> WhereGroup GmbH
>> Schwimmbadstr. 2
>> 79100 Freiburg
>> Germany
>>
>> Fon: +49 (0)761 / 519 102 - 61
>> Fax: +49 (0)761 / 519 102 - 11
>> stefan.gi...@wheregroup.comwww.wheregroup.com
>> Geschäftsführer:
>> Olaf Knopp, Peter Stamm
>> Amtsgericht Bonn, HRB 9885
>>
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Re: [Qgis-user] convex and concave areas

2021-05-05 Thread Sebastian Gutwein

In the QGIS toolbox there is a Saga algorithm called Terrain Surface
Convexity that does calculate convexity or concavity. I have never used it.
http://www.saga-gis.org/saga_tool_doc/2.2.3/ta_morphometry_21.html
https://sourceforge.net/p/saga-gis/discussion/354013/thread/3fadd3e7/

On Wed, May 5, 2021 at 4:14 AM Stefan Giese (WhereGroup) <
stefan.gi...@wheregroup.com> wrote:

> one process could be:
>
>- 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
>- substract the filtered from the original
>- select values > or < your cutoff
>- convert this into polygons
>
> see
> 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
> for further reading
>
> Hope this helps
>
> Stefan
> Am 05.05.2021 um 10:02 schrieb Azzurra Lentini:
>
> Hi list,
> I need to find the convex and concave areas from a dtm raster file. Do you
> have any suggestions?
> Thanks
>
> --
> Adjunct Professor University "Roma Tre"
> Gis Applied for Environmental studies
> Risk modelling & Hydrogeology
> Consultant DFID-UK, United Nations, EU projects
> AZZURRA LENTINI
> ++
> Italy Mobile Tel.: **(39) 338 24 40 676
> ++
> SKYPE azzurrahydro
> ++
>
> *azzurralent...@gmail.com *
>
> *azzurra.lent...@uniroma3.it  *
> ++
> *Par respect pour l'environnement,*
>
> *n'imprimez ce mail qu'en cas d'absolue nécessité*
>
>
>
>
>
>
> ___
> Qgis-user mailing listqgis-u...@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>
> --
> Mit freundlichen Grüßen
> Stefan Giese
> Projektleiter/Consultant
> 
> Aufwind durch Wissen!
> Web-Seminare und Online-Schulungen
> bei der www.foss-academy.com
> 
> WhereGroup GmbH
> Schwimmbadstr. 2
> 79100 Freiburg
> Germany
>
> Fon: +49 (0)761 / 519 102 - 61
> Fax: +49 (0)761 / 519 102 - 11
> stefan.gi...@wheregroup.comwww.wheregroup.com
> Geschäftsführer:
> Olaf Knopp, Peter Stamm
> Amtsgericht Bonn, HRB 9885
>
> ___
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Re: [Qgis-user] convex and concave areas

2021-05-05 Thread Stefan Giese (WhereGroup)


one process could be:

 * 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
 * substract the filtered from the original
 * select values > or < your cutoff
 * convert this into polygons

see 
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 
for further reading


Hope this helps

Stefan

Am 05.05.2021 um 10:02 schrieb Azzurra Lentini:

Hi list,
I need to find the convex and concave areas from a dtm raster file. Do 
you have any suggestions?

Thanks

--
Adjunct Professor University "Roma Tre"
Gis Applied for Environmental studies
Risk modelling & Hydrogeology
Consultant DFID-UK, United Nations, EU projects
AZZURRA LENTINI
++
Italy Mobile Tel.: **(39) 338 24 40 676
++
SKYPE azzurrahydro
++

*_azzurralent...@gmail.com _*

*_azzurra.lent...@uniroma3.it  _**__*

++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*






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--
Mit freundlichen Grüßen
Stefan Giese
Projektleiter/Consultant

Aufwind durch Wissen!
Web-Seminare und Online-Schulungen
bei der www.foss-academy.com

WhereGroup GmbH
Schwimmbadstr. 2
79100 Freiburg
Germany

Fon: +49 (0)761 / 519 102 - 61
Fax: +49 (0)761 / 519 102 - 11

stefan.gi...@wheregroup.com
www.wheregroup.com
Geschäftsführer:
Olaf Knopp, Peter Stamm
Amtsgericht Bonn, HRB 9885

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[Qgis-user] convex and concave areas

2021-05-05 Thread Azzurra Lentini

Hi list,
I need to find the convex and concave areas from a dtm raster file. Do you
have any suggestions?
Thanks

-- 
Adjunct Professor University "Roma Tre"
Gis Applied for Environmental studies
Risk modelling & Hydrogeology
Consultant DFID-UK, United Nations, EU projects
AZZURRA LENTINI
++
Italy Mobile Tel.: **(39) 338 24 40 676
++
SKYPE azzurrahydro
++

*azzurralent...@gmail.com *

*azzurra.lent...@uniroma3.it  *
++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*
___
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Re: [Qgis-user] convex and concave areas

Re: [Qgis-user] convex and concave areas

Re: [Qgis-user] convex and concave areas

[Qgis-user] convex and concave areas

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