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<p class="MsoNormal">Good afternoon,<o:p></o:p></p>
<p class="MsoNormal">Thanks so much for your usefull reply. <o:p></o:p></p>
<p class="MsoNormal">I'm taking the liberty to ask a little aditionnal question. <o:p>
</o:p></p>
<p class="MsoNormal">Still for segmentation needs, i plan to set for the input data, not only the multi spectral data (B,G,R,PIR) but also
<o:p></o:p></p>
<p class="MsoNormal">ndvi, texture, DEM...And before to stack all these variables (and before to plan to run a PCA for reduce the information), could you confirm to that i need to rescale all the variables ? For example, for the NDVI (default Values from -1
to 1), i need to rescale its from 0 to 255 (if my multi spectral data is encoded on 8 bits unsigned). And i have to the same rescaling for others variables?
<o:p></o:p></p>
<p class="MsoNormal">Thank so much.<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">De :</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Veronica Andreo <veroandreo@gmail.com>
<br>
<b>Envoyé :</b> mardi 4 mars 2025 23:33<br>
<b>À :</b> Laurent CELATI <lcelati@biotope.fr><br>
<b>Cc :</b> grass-user@lists.osgeo.org<br>
<b>Objet :</b> Re: [GRASS-user] Segmentation : how to add texture criterion ? (not only colour/spectral variable)<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hello Laurent, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">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. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">hth, <o:p></o:p></p>
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<p class="MsoNormal">Vero<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[0] <a href="https://grass.osgeo.org/grass-stable/manuals/i.segment.html" target="_blank">https://grass.osgeo.org/grass-stable/manuals/i.segment.html</a><o:p></o:p></p>
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<p class="MsoNormal">[1] <a href="https://grass.osgeo.org/grass-stable/manuals/addons/i.segment.uspo.html" target="_blank">https://grass.osgeo.org/grass-stable/manuals/addons/i.segment.uspo.html</a><o:p></o:p></p>
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<p class="MsoNormal">[2] <a href="https://doi.org/10.3390/rs9040358" target="_blank">https://doi.org/10.3390/rs9040358</a><o:p></o:p></p>
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<p class="MsoNormal">[3] <a href="https://doi.org/10.3390/rs10091440" target="_blank">https://doi.org/10.3390/rs10091440</a><o:p></o:p></p>
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<p class="MsoNormal">[4] <a href="https://grass.osgeo.org/grass-stable/manuals/r.texture.html" target="_blank">https://grass.osgeo.org/grass-stable/manuals/r.texture.html</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">El mar, 4 mar 2025 a las 12:20, Laurent CELATI via grass-user (<<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>>) escribió:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello.<br>
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 :
<a href="https://www.orfeo-toolbox.org/CookBook-7.0/Applications/app_GenericRegionMerging.html" target="_blank">
GenericRegionMerging — Orfeo ToolBox 7.0.0 documentation</a> with those folowing settings<o:p></o:p></p>
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<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
input image : spot 6/7 satelite image (band blue, green, red, near infrared)<br>
or Aerial french mapping agency images (50 cms bd ortho with green, red and near infrared).<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Homogenity criterion to use : Baatz & Schape<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Threshold for the criterion : 500<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Number of iterations`: 0<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Weight for the spectral homogeneity : 0.1<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Weight for the spatial homogeneity : 0.1<o:p></o:p></li></ul>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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.<br>
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?<br>
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?<br>
Thanks so much for your guidances.<o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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<a href="https://lists.osgeo.org/mailman/listinfo/grass-user" target="_blank">https://lists.osgeo.org/mailman/listinfo/grass-user</a><o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span class="gmailsignatureprefix">-- </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Dra. Verónica Andreo<br>
Investigadora Adjunta de CONICET</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Instituto Gulich (CONAE - UNC)</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Centro Espacial Teófilo Tabanera (CETT)</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Falda del Cañete - Córdoba, Argentina</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">+54 3547 400000 int. 1153</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888"><a href="https://eu01.z.antigena.com/l/ZU13wcvQ5667aVP9D4sxjNbhD6LbbftuuvORk3hL1tmpYxTPazkeg7p8G7sk-5CKnXF9kYTehe~Nff-Aao4OI18GgOQYVTFxlORVAIcSAxYI5PHLGQvJof4iQL2HlI-Pr_tx6mvuLVnNWU6dzTfmI83H3Xkfer_-3N7VC44PmiVWmzKTfHs-DXUSN1x" target="_blank">https://eu01.z.antigena.com/l/ZU13wcvQ5667aVP9D4sxjNbhD6LbbftuuvORk3hL1tmpYxTPazkeg7p8G7sk-5CKnXF9kYTehe~Nff-Aao4OI18GgOQYVTFxlORVAIcSAxYI5PHLGQvJof4iQL2HlI-Pr_tx6mvuLVnNWU6dzTfmI83H3Xkfer_-3N7VC44PmiVWmzKTfHs-DXUSN1x
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