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<p>Gordon,</p>
<p>urn:ogc:def:coordinateOperation:EPSG::1311 is from ED50 to WGS84,
so what you observe with gdaltransform is expected. You'd get the
correct result by just switching EPSG:4326 and EPSG:4230</p>
<p>Regarding the use of the API, it is true that this was lacking.
Adressed per <a class="moz-txt-link-freetext" href="https://github.com/OSGeo/gdal/pull/6175">https://github.com/OSGeo/gdal/pull/6175</a></p>
<p>Even<br>
</p>
<div class="moz-cite-prefix">Le 09/08/2022 à 13:16, Gordon Paterson
a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CAF9Cb5j6r1sRrVp_YgxdO-_dFmEo9jC+3FqQxVSDz769H3kzhg@mail.gmail.com">
<div dir="ltr">Hi everyone,
<div><br>
</div>
<div>GDAL 3.5.0</div>
<div><br>
</div>
<div>I have an application written in c# that takes data in
WGS84 and transforms the coordinates to the relevant local
projected CRS. </div>
<div><br>
</div>
<div>In the code I use a URN with the EPSG transformation code,
for example for ED50 data -</div>
<div><br>
</div>
<blockquote>
<div><span>urn:ogc:def:coordinateOperation:EPSG::1311</span></div>
</blockquote>
<div><span><br>
</span></div>
<div><span>to convert between EPSG:4326 and EPSG:4230 and it
works great for going from EPSG:4230 > EPSG:4326 but it
doesn't give the correct results the other way.</span></div>
<div><span><br>
</span></div>
<div><span>Checking the coordinates with gdaltransform from the
command line using the following -</span></div>
<div><span><br>
</span></div>
<blockquote>
<div>gdaltransform -s_srs EPSG:4326 -t_srs EPSG:4230 -ct
urn:ogc:def:coordinateOperation:EPSG::1311</div>
</blockquote>
<div><span><br>
</span></div>
<div><span>I get this -</span></div>
<div><span><br>
</span></div>
<blockquote>
<div><span>WGS84 (EPSG:4326)</span></div>
<div><span> </span><span>2.25661712354279 56.4136492649363</span></div>
<div><span><br>
</span></div>
<div><span>ED50 (EPSG:4230)</span></div>
<div><span>2.25511244583886 56.4129769077511</span></div>
</blockquote>
<div><span><br>
</span></div>
<div><span>which are the same coordinates I get through code,
which is not right, but with the -i switch -</span></div>
<div><span><br>
</span></div>
<blockquote>
<div>gdaltransform -s_srs EPSG:4326 -t_srs EPSG:4230 -ct
urn:ogc:def:coordinateOperation:EPSG::1311 -i</div>
</blockquote>
<div><br>
</div>
<div>I get this -</div>
<div><br>
</div>
<blockquote>
<div><span>ED50 (EPSG:4230)</span></div>
<div><span>2.25812179682132 56.414321584992</span></div>
</blockquote>
<div><span><br>
</span></div>
<div><span>which is correct.</span></div>
<div><span><br>
</span></div>
<div><span>In the gdal docs there is a bReverseCT boolean
parameter for SetCoordinateOperation that is not accessible
and is set to always be false in the SWIG interface.</span></div>
<div><span><br>
</span></div>
<div><span>I set the correct Axis mapping on the spatial
reference within code. </span><span>I'm no doubt missing
something, what am I doing wrong? </span></div>
<div><span><br>
</span></div>
<div><span>thanks very much,</span></div>
<div><span><br>
</span></div>
<div><span>-Gordon</span></div>
<div><br>
</div>
<div><span><br>
</span></div>
<div><span><br>
</span></div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
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My software is free, but my time generally not.</pre>
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