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<p class="MsoNormal"><span style="font-size:11.0pt">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">See this example on how I do that in Julia. At the bottom it’s GDAL functions that are being used.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><a href="https://www.generic-mapping-tools.org/GMTjl_doc/examples/misc/buffer/#example_2628794262856115982">https://www.generic-mapping-tools.org/GMTjl_doc/examples/misc/buffer/#example_2628794262856115982</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Joaquim<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><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">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal-dev <gdal-dev-bounces@lists.osgeo.org>
<b>On Behalf Of </b>Schumacher, Mia via gdal-dev<br>
<b>Sent:</b> Friday, June 20, 2025 11:31 AM<br>
<b>To:</b> gdal-dev@lists.osgeo.org<br>
<b>Subject:</b> Re: [gdal-dev] Buffer in geodetic space<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p><span style="font-family:"Avenir",serif">Hi Javier,</span><o:p></o:p></p>
<p><span style="font-family:"Avenir",serif">there is a QGIS plugin called 'Beeline' that measures great circle distances:
<a href="https://plugins.qgis.org/plugins/Beeline/">https://plugins.qgis.org/plugins/Beeline/</a></span><o:p></o:p></p>
<p><span style="font-family:"Avenir",serif">Hope that helps?</span><o:p></o:p></p>
<p><span style="font-family:"Avenir",serif">Cheers,<br>
Mia</span><o:p></o:p></p>
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<p class="MsoNormal">On 20.06.25 12:06, Javier Jimenez Shaw via gdal-dev wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Yesterday I read an article in a newspaper with an image showing distances from a country that was not considering that the Earth is spheric. It is not the first time; it will not be the last one. As we all (should) know, measuring large
distances (thousands of kilometers) in projected coordinates is wrong.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Is there any way to do it properly in GDAL or QGIS? What I mean is that the distance (in meters) for a buffer (or parallel line) is measured along greatest circles perpendicular to the source geometry.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If not, should we implement it somewhere? (GDAL, QGIS, somewhere else)<o:p></o:p></p>
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<p class="MsoNormal">I guess that we need PROJ for that algorithm to compute the distance along a great circle.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal">Javier<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">PS trying in QGIS, I see it uses ST_Buffer from an sqlite query. But it is not what I am talking about. That is the "wrong" solution for large distances.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>gdal-dev mailing list<o:p></o:p></pre>
<pre><a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><o:p></o:p></pre>
<pre><a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a><o:p></o:p></pre>
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