[GRASS-user] Segmentation : how to add texture criterion ? (not only colour/spectral variable)

[Veronica Andreo]

Hello Laurent,

You might want to check i.segment [0] within the core tools of GRASS and
i.segment.uspo [1] for unsupervised parameter optimization within GRASS
extensions. Also, there are  nice papers by Grippa et al [2] and Georganos
et al [3] that show the segmentation/OBIA workflow within GRASS.

To include texture rasters within segmentation, have a look at
r.texture [4] tool in GRASS. What I usually do is to estimate textures from
a panchromatic higher res band.

hth,
Vero

[0] https://grass.osgeo.org/grass-stable/manuals/i.segment.html
[1] https://grass.osgeo.org/grass-stable/manuals/addons/i.segment.uspo.html
[2] https://doi.org/10.3390/rs9040358
[3] https://doi.org/10.3390/rs10091440
[4] https://grass.osgeo.org/grass-stable/manuals/r.texture.html

El mar, 4 mar 2025 a las 12:20, Laurent CELATI via grass-user (<
grass-user at lists.osgeo.org>) escribió:

>
>
> Hello.
> My goal is to generate a relevant segmentation that would delimit the main
> physiopnomic units (homogenous areas). Up to now, I have done several tests
> with qgis and orfeotoolbox 9 with the OTB Generic Region merging module : GenericRegionMerging
> — Orfeo ToolBox 7.0.0 documentation
> <https://www.orfeo-toolbox.org/CookBook-7.0/Applications/app_GenericRegionMerging.html>
> with those folowing settings
>
>    - input image : spot 6/7 satelite image (band blue, green, red, near
>    infrared)
>    or Aerial french mapping agency images (50 cms bd ortho with green,
>    red and near infrared).
>    - Homogenity criterion to use : Baatz & Schape
>    - Threshold for the criterion : 500
>    - Number of iterations`: 0
>    - Weight for the spectral homogeneity : 0.1
>    - Weight for the spatial homogeneity : 0.1
>
> The result is rather interesting for certain areas, in particular crops
> areas, without too much vegetation. on the other hand, the method does not
> seems optimal, in particular for forest areas.
>
> Perhaps for these forest areas, the color/spectral criterion is not
> relevant. It would be better to generate / integrate texture information?
> As far as i understood, this GRM OTB module is based only on
> spectral/colour criterion but not take into consideration texture
> information.
> Are there other qgis/grass/ orfeotoolbox or whatever other segmentation
> module that takes into account not only the color criterion (spectral) but
> also texture information?
> If this is not the case, should i create some kind of new raster (add a
> band to my existing color infrared raster) dedicated to texture and/or ndvi
> information?
> Thanks so much for your guidances.
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>


-- 
Dra. Verónica Andreo
Investigadora Adjunta de CONICET
Instituto Gulich (CONAE - UNC)
Centro Espacial Teófilo Tabanera (CETT)
Falda del Cañete - Córdoba, Argentina
+54 3547 400000 int. 1153
https://veroandreo.gitlab.io/
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