Clifford J Mugnier
cjmce at lsu.edu
Sat Feb 26 19:07:26 EST 2005
Your conclusion is correct with regard to PROJ4; it does not support datum
shifts of any kind. Mr. Evenden is of the same philosophy as John P.
Snyder was in regard to that topic.
Clifford J. Mugnier
Chief of Geodesy and
CENTER FOR GEOINFORMATICS
Department of Civil Engineering
LOUISIANA STATE UNIVERSITY
Baton Rouge, LA 70803
Voice and Facsimile: (225) 578-8536 [Academic]
Voice and Facsimile: (225) 578-4474 [Research]
Quick first question from a newcomer exploring the capabilities of Proj.4
before attempting to compile the code.
I've read the documentation plus recent threads on this list serve that
discuss datum shifts (of the 7-parameter variety), which, apparently,
Proj.4 does not support. My question is whether Proj.4 supports
Earth-Centered Earth-Fixed (ECEF) geocentric Cartesian coordinates or not
(i.e, lat/lon/hgt => ECEF X/Y/Z). Seems it would be simple to build that
functionality into the Proj.4 code, but I gather that the documentation's
references to "cartesian coordinates" means Eastings/Northings in
projected space, and not ECEF. Non-support for geocentric datum shifting
seems to support this tentative conclusion. Can someone confirm for me?
Thanks, Noel Zinn
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