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<p>Javier,</p>
<p>I suspect you might be able to apply the azimuth by using the
infamous +proj=ob_tran. The tricky part will be to find on which
parameter(s) of ob_tran (o_lat_p, o_lon_p, lon_0) to map it.</p>
<p>Possibly relevant, there's at least 2 different code
implementations attempting at reproducing the Spilhaus from Esri,
which include a azimuth parameter:<br>
</p>
<p>- cf
<a class="moz-txt-link-freetext" href="https://github.com/OSGeo/PROJ/issues/1851#issuecomment-943138537">https://github.com/OSGeo/PROJ/issues/1851#issuecomment-943138537</a></p>
<p>- or
<a class="moz-txt-link-freetext" href="https://github.com/neocarto/bertin/blob/main/src/projections/spilhaus.js">https://github.com/neocarto/bertin/blob/main/src/projections/spilhaus.js</a>
+ <a class="moz-txt-link-freetext" href="https://github.com/d3/d3-geo/blob/main/src/rotation.js">https://github.com/d3/d3-geo/blob/main/src/rotation.js</a></p>
<p>The maths ressemble those of proj=ob_tran</p>
<p>Even<br>
</p>
<div class="moz-cite-prefix">Le 31/05/2023 à 00:24, Javier Jimenez
Shaw a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CADRrdKuAJU=4XN-7F4LttWrPZwk0OHdAq386VsB8r4-=rdSNig@mail.gmail.com">
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<div>Hi</div>
<div><br>
</div>
<div>Some use cases of Esri "local" projection are arriving to
my desk. This projection works in Esri software, but not in
PROJ (obviously also not in QGIS)<br>
</div>
<br>
<div>One example is this WKT1_ESRI<br>
</div>
<br>
PROJCS["Hycroft001",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Local"],PARAMETER["False_Easting",13264.924],PARAMETER["False_Northing",46473.418],PARAMETER["Scale_Factor",1.00025],PARAMETER["Azimuth",15.786],PARAMETER["Longitude_Of_Center",-116.7048269],PARAMETER["Latitude_Of_Center",42.88212865],UNIT["Foot_US",0.3048006096012192]]<br>
<div>
<div><br>
</div>
<div>Looking at their documentation, it seems to be this one:<br>
</div>
<div><a
href="https://desktop.arcgis.com/en/arcmap/latest/map/projections/local.htm"
moz-do-not-send="true" class="moz-txt-link-freetext">https://desktop.arcgis.com/en/arcmap/latest/map/projections/local.htm</a></div>
<div><br>
</div>
<div>The biggest difference I see with the Orthographic from
PROJ is the Azimut parameter. I have the impression that the
azimut is just a rotation of the axes, but it is not clear
to me in the Snyder book (page 145. If you do not have it,
it is available at <a
href="https://pubs.er.usgs.gov/publication/pp1395"
moz-do-not-send="true" class="moz-txt-link-freetext">https://pubs.er.usgs.gov/publication/pp1395</a>
)</div>
<div><br>
</div>
<div>Is there are alternative in PROJ?</div>
<div>Does it make sense to add this transformation?</div>
<div><br>
</div>
<div>Thanks<br>
</div>
<div>Javier<br>
</div>
</div>
<div>
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<div>.___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ...
.... ._ .__</div>
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<br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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</blockquote>
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My software is free, but my time generally not.</pre>
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