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Re: UTM Map Projection Produces Incorrect Results [message #78171 is a reply to message #78170]

Mon, 31 October 2011 10:02

MarioIncandenza
Messages: 231
Registered: February 2005

Senior Member

David,

I am still confused. The first line of code in your article uses a
keyword to MAP_PROJ_INIT, "ELLIPSOID='wgs84'", which I can find
nowhere in the documentation of MAP_PROJ_INIT. I see a DATUM keyword
(that doesn't solve the problem described-- map parameters are still
spherical when I specify DATUM=8). Was this ELLIPSOID keyword
introduced in a recent version?

Anyway, perusing the group archive, I see that Andrew Cool in 2004
said "I suspect that there is an inherent problem in IDL's mapping
routines in the way they handle Transverse Mercator and rotation."

Might be worth updating this page with new information:
http://www.idlcoyote.com/map_tips/utm_to_ll.html

proj.4 is nice any everything, but one of the strongest points
remaining in IDL's favor is that it does not use external libraries
and thus does not have dependency troubles that plague other
solutions. In the short-term, they should just fix the bug-- I
seriously doubt that there was ever a version of the GCTP software
that couldn't handle UTM.

--Edward H.

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[Message index]

		Re: UTM Map Projection Produces Incorrect Results By: David Fanning on Mon, 31 October 2011 12:23
		Re: UTM Map Projection Produces Incorrect Results By: David Fanning on Mon, 31 October 2011 12:20
		Re: UTM Map Projection Produces Incorrect Results By: Fabzou on Mon, 31 October 2011 12:08
		Re: UTM Map Projection Produces Incorrect Results By: lecacheux.alain on Mon, 31 October 2011 11:33
		Re: UTM Map Projection Produces Incorrect Results By: David Fanning on Mon, 31 October 2011 11:21
		Re: UTM Map Projection Produces Incorrect Results By: Fabzou on Mon, 31 October 2011 11:06
		Re: UTM Map Projection Produces Incorrect Results By: David Fanning on Mon, 31 October 2011 10:42
		Re: UTM Map Projection Produces Incorrect Results By: MarioIncandenza on Mon, 31 October 2011 10:02
		Re: UTM Map Projection Produces Incorrect Results By: Andrew Cool on Thu, 03 November 2011 19:11
		Re: UTM Map Projection Produces Incorrect Results By: chris_torrence@NOSPAM on Tue, 01 November 2011 09:04

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