[PROJ] Does WGS84 automatically use EGM96 in PROJ?

[Clifford J Mugnier]

Apples and oranges.  ECEF to ENU is a purely geometric transformation.  Earth Gravity Models have no relationship in such a transformation.


Clifford J. Mugnier, c.p., c.m.s.

Chief of Geodesy, Emeritus

LSU Center for GeoInformatics (ERAD 266)

Dept. of Civil Engineering

LOUISIANA STATE UNIVERSITY

Baton Rouge, LA  70803

Research:   (225) 578-4578

Cell:           (225) 328-8975

honorary lifetime member, lsps

fellow emeritus, asprs

member, apsg

________________________________
From: PROJ <proj-bounces at lists.osgeo.org> on behalf of Andrew Kelley <akelley2500 at gmail.com>
Sent: Monday, January 10, 2022 3:54 PM
To: proj at lists.osgeo.org <proj at lists.osgeo.org>
Subject: [PROJ] Does WGS84 automatically use EssGM96 in PROJ?

Hello,

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 one website I found<http://wiki.gis.com/wiki/index.php/WGS84> says, "Presently WGS 84 uses the 1996 Earth Gravitational Model (EGM96) geoid, revised in 2004."  But I found out elsewhere online<https://en.wikipedia.org/wiki/Earth_Gravitational_Model> that there is an EGM84, EGM96, and an EGM2008.

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.

Thank you for your time,
Andrew Kelley
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20220110/88e2d6fa/attachment.html>