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<div dir="ltr" data-setdir="false">I don't know of a way to do it in QGIS, but you can use the ST_ApproximateMedialAxis function in PostGIS. Note your PostGIS needs to be compiled with the SFCGAL library. Note that not all PostGIS installers will include SFCGAL. </div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Also you may still need to clean up the data further, my understanding is that this is a very difficult problem and an area of research in computer science. </div><div dir="ltr" data-setdir="false"><br></div><div><a href="https://postgis.net/docs/ST_ApproximateMedialAxis.html" rel="nofollow" target="_blank">https://postgis.net/docs/ST_ApproximateMedialAxis.html</a><br></div><div><br></div><div dir="ltr" data-setdir="false">-Thayer</div><div dir="ltr" data-setdir="false"><br></div><div><br></div>
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On Tuesday, October 12, 2021, 05:46:01 AM EDT, qgis-user-request@lists.osgeo.org <qgis-user-request@lists.osgeo.org> wrote:</div><div><div dir="ltr">------------------------------<br></div><div dir="ltr"><br></div><div dir="ltr">Message: 3<br></div><div dir="ltr">Date: Mon, 11 Oct 2021 18:49:23 -0600<br></div><div dir="ltr">From: Allan L?pez <<a href="mailto:allosa01@gmail.com" rel="nofollow" target="_blank">allosa01@gmail.com</a>><br></div><div dir="ltr">To: <a href="mailto:Qgis-user@lists.osgeo.org" rel="nofollow" target="_blank">Qgis-user@lists.osgeo.org</a><br></div><div dir="ltr">Subject: [Qgis-user] Middle line of a river basin<br></div><div dir="ltr">Message-ID:<br></div><div dir="ltr"> <CABOeUQ-jaGXtfoZZsN=<a href="mailto:44nn8xTFVXixF_jgxwvndQ3J6_fJnFg@mail.gmail.com" rel="nofollow" target="_blank">44nn8xTFVXixF_jgxwvndQ3J6_fJnFg@mail.gmail.com</a>><br></div><div dir="ltr">Content-Type: text/plain; charset="utf-8"<br></div><div dir="ltr"><br></div><div dir="ltr">Dear All,<br></div><div dir="ltr"><br></div><div dir="ltr">I need to automatically delineate the middle line of a river basin/valley<br></div><div dir="ltr">bounded by a Shp and then to construct lines perpendicular to it spaced at<br></div><div dir="ltr">will. All this to get the<br></div><div dir="ltr">Transverse topographic symmetry factor (T).<br></div><div dir="ltr"><br></div><div dir="ltr">My appreciation in advance,<br></div><div dir="ltr"><br></div><div dir="ltr">Allan L?pez<br></div><div dir="ltr">-------------- next part --------------<br></div><div dir="ltr">An HTML attachment was scrubbed...<br></div><div dir="ltr">URL: <<a href="http://lists.osgeo.org/pipermail/qgis-user/attachments/20211011/28e65c52/attachment-0001.html" rel="nofollow" target="_blank">http://lists.osgeo.org/pipermail/qgis-user/attachments/20211011/28e65c52/attachment-0001.html</a>><br></div><div dir="ltr">------------------------------<br></div><div dir="ltr"><br></div></div>
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