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Re: Amazingly accurate UTM <-> Lat/Lon transformations [message #85920 is a reply to message #85914]

Wed, 18 September 2013 06:19

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Fabien writes:

> I forwarded Tom's post to my colleagues, because many of them are not
> aware of these problems and Tom nicely showed the huge discrepancies
> that can occur when using UTM. Having said this, I am also concerned
> that even if the LonLat->EastingsNothings->LonLat transforms work better
> with Tom's code, it might still not be a good idea to use UTM for large
> maps.
>

The UTM projection is surely one of the most abused map projections in
history. Perhaps scientists should be made to take a quick course on it
in additional the the mandatory typing classes I've been advocating
forever.

> Regarding the map projections in IDL, it seems that IDL is far behind
> many other GIS softwares (correct me if I'm wrong):
> - the panel of "out of the box" projections is small
> - there is no datum shift transformation tool (!)
> - the accuracy, as shown by Tom, could be higher
>
> I believe this is due to the fact that Exelis wants to sell ENVI to IDL
> users in need for more complete/accurate projection engines...

Now, now, Fabien, I'm not dead yet. Please don't be usurping my role of
cynic on this newsgroup. ;-)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		Amazingly accurate UTM <-> Lat/Lon transformations By: tom.grydeland on Tue, 17 September 2013 01:50
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: David Fanning on Tue, 17 September 2013 11:16
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: Fabzi on Wed, 18 September 2013 02:13
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: David Fanning on Wed, 18 September 2013 06:19
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: Andy Sayer on Wed, 18 September 2013 07:20
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: tom.grydeland on Wed, 18 September 2013 02:15
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: David Fanning on Wed, 18 September 2013 06:04
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: tom.grydeland on Thu, 19 September 2013 05:40
		Re: Amazingly accurate UTM <-> Lat/Lon transformations By: David Fanning on Thu, 19 September 2013 05:47

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