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Apples and oranges. ECEF to ENU is a purely geometric transformation. Earth Gravity Models have no relationship in such a transformation.</div>
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<p><font face="Copperplate Gothic Bold">Clifford J. Mugnier, c.p., c.m.s.</font></p>
<p><font face="Copperplate Gothic Bold">Chief of Geodesy, <i>Emeritus</i></font></p>
<p><font face="Copperplate Gothic Bold">LSU Center for GeoInformatics (ERAD 266)</font></p>
<p><font face="Copperplate Gothic Bold">Dept. of Civil Engineering </font></p>
<p><font face="Copperplate Gothic Bold"><b>LOUISIANA STATE UNIVERSITY</b></font></p>
<p><font face="Copperplate Gothic Bold">Baton Rouge, LA 70803</font></p>
<p><font face="Copperplate Gothic Bold">Research: (225) 578-4578</font></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> PROJ <proj-bounces@lists.osgeo.org> on behalf of Andrew Kelley <akelley2500@gmail.com><br>
<b>Sent:</b> Monday, January 10, 2022 3:54 PM<br>
<b>To:</b> proj@lists.osgeo.org <proj@lists.osgeo.org><br>
<b>Subject:</b> [PROJ] Does WGS84 automatically use EssGM96 in PROJ?</font>
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<div dir="ltr"><font color="#000000">Hello,</font>
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<font color="#000000">My team is using PROJ to convert ECEF coordinates to ENU coordinates (relative to a fixed point on the surface of the Earth). When we use WGS84 for this, does that automatically use EGM96? What makes me think EGM96 is used is that <a href="http://wiki.gis.com/wiki/index.php/WGS84" target="_blank">one
website I found</a> says, "Presently WGS 84 uses the 1996 Earth Gravitational Model (EGM96) geoid, revised in 2004." But I found out <a href="https://en.wikipedia.org/wiki/Earth_Gravitational_Model" target="_blank">elsewhere online</a> that there is an EGM84,
EGM96, and an EGM2008.</font></div>
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<font color="#000000">Note: We are currently using proj-strings, though we would be happy to use object codes (ie. EPSG:XXXX) if we knew how to specify the origin of the ENU coordinates when using an object code.</font></div>
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<font color="#000000">Thank you for your time,</font></div>
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<font color="#000000">Andrew Kelley</font></div>
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