<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p><br>
</p>
<div class="moz-cite-prefix">Le 18/10/2023 à 17:57, Javier Jimenez
Shaw via PROJ a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CADRrdKt0u=Vd4uzmOGDmk5rRbo6zh5vE9S2D-N+s43W0QXGvig@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div>Hi</div>
<div><br>
</div>
<div>What is the difference between PJ_TYPE_GEODETIC_CRS and
PJ_TYPE_GEOCENTRIC_CRS?</div>
</div>
</blockquote>
<p>Geocentric is a specialization of Geodetic (not in the standard,
but so common that we have a subtype for it)</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:CADRrdKt0u=Vd4uzmOGDmk5rRbo6zh5vE9S2D-N+s43W0QXGvig@mail.gmail.com">
<div dir="ltr">
<div>In <a href="http://crs-explorer.proj.org"
moz-do-not-send="true">crs-explorer.proj.org</a> you can
easily see how there are no Geodetic systems in EPSG and there
are no Geocentric systems in IAU_2015...</div>
</div>
</blockquote>
<p>Geodetic CRS in EPSG are geographic 2D, geographic 3D or
geocentric. No weird/unusual geodetic ones</p>
<p><br>
</p>
<p>In IAU_2015, there's indeed no geocentric CRS definition. You may
get PJ_TYPE_GEODETIC_CRS for CRS like IAU:19902 "Mercury (2015) /
Ocentric" whose coordinate system is spherical with planetocentric
latitude and longitude. This is close to a geographic CRS, except
that you use -ocentric latitude (angle between the equatorial
plane and the point on the ellipsoid) instead of a -ographic
latitude (the angle between the equatorial plane and the normal to
the ellipsoid at the point of interest).</p>
<span style="white-space: pre-wrap">
</span>
<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-freetext" href="http://www.spatialys.com">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
</body>
</html>