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<div class="moz-cite-prefix">Le 12/08/2024 à 18:44, Laura, Jason R
via PROJ a écrit :<br>
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cite="mid:CO6PR09MB8775D4794D70AC1C7DA5F244B9852@CO6PR09MB8775.namprd09.prod.outlook.com">
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List, </div>
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I have a set of body-centered body-fixed coordinates that were
computed with an ellipsoid of +a=3396190 +b=3376200. I am
attempting to reproject these into a spherical datum
(+R=3396190) using the pipeline syntax. For example, </div>
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+proj=pipeline +units=m</div>
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+step +proj=cart +a=3396190 +b=3376200</div>
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+step +proj=cart +R=3396190 </div>
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Which is failing with a unit warning. I suspect I am missing
something basic.</div>
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You need to add +inv in the last step to go from ECEF to lon-lat
coordinate space<br>
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cite="mid:CO6PR09MB8775D4794D70AC1C7DA5F244B9852@CO6PR09MB8775.namprd09.prod.outlook.com">
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I have looked at the geodesic -> Helmert -> geodesic
transformation tutorial, but I am clearly misunderstanding
something (<a
href="https://proj.org/en/9.3/tutorials/EUREF2019/exercises/pipelines.html#geodetic-helmert-geodetic"
id="LPlnk336899" moz-do-not-send="true"
class="moz-txt-link-freetext">https://proj.org/en/9.3/tutorials/EUREF2019/exercises/pipelines.html#geodetic-helmert-geodetic</a>)</div>
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Looking at these docs, I tried:</div>
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+proj=pipeline</div>
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+step +proj=cart +a=3396190 +b=3376200</div>
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+step +proj=helmert +z=19990 +convention=position_vector</div>
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+step +inv +proj=cart +R=3396190</div>
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But I get an invalid latitude error (which I believe means I am
misspecifying the input system).</div>
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Works for me. The input coordinate order is longitude, latitude, Z.<br>
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Any suggestions appreciated, </div>
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Jay</div>
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