[Qgis-user] Identifying / Digitising small surface features automatically

[Stefan Giese (WhereGroup)]

Hi,

yes that is possible to automate this process. The main idea is to use 
an blur-filter on your DSM - a normalized 2D gauss kernel array for 
convolutions - where the size of the kernel determines the wide of the 
features that will be extracted. The second step is to build the 
difference between DSM and DSM_blured. So the small features will 
remain. for more theory see: 
https://www.isprs.org/proceedings/xxxvi/8-w2/SITTLER.pdf

Some years ago - in my former ArcGIS job - I've wrote a small python 
routine for ArcGis using numpy to do the job. The ArcGis script could be 
found here: https://files.wheregroup.com/s/qMdZB8TH8FWWboQ and can be 
adapted to QGIS.

Best regards

Stefan

Am 05.02.2024 um 20:45 schrieb Steve Research via QGIS-User:
> Does anyone know how to locate small features on a digital surface model (dsm) in qgis and get their coordinates?
>
> I have a field surface with distributed molehills they show up in the dsm but is there a tool that will mark them as objects to digitise their locations?
>
> I have Qgis + Saga etc. but don’t know if there is a process to mark these without having to do it by hand (I have lots of fields to do!).
>
>
>
> Sent from my iPhone
>
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-- 
Mit freundlichen Grüßen
Stefan Giese
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