[OSRS-PROJ] proj4 parameter question regarding UTM

[Ed McNierney]

Peter -

If that's what you're looking for, you got the right answer.

You concluded that it was wrong because you compared it to the zone 7
northing and easting, not the pseudo-zone 10 values.

While you can mathematically do what you're intending, you will get
severe distortion in your data.  Using "tmerc instead" won't help - UTM
is simply a particular form of tmerc, and using tmerc for such a large
extent will produce a comparable degree of distortion.

Depending on your application, that distortion might be acceptable.  The
reason UTM zones are 6 degrees wide is based on a desire to limit the
extent of that distortion.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com
-----Original Message-----
From: pw [mailto:p.willis at telus.net] 
Sent: Friday, February 06, 2004 7:17 PM
To: osrs-proj at remotesensing.org
Subject: Re: [OSRS-PROJ] proj4 parameter question regarding UTM

Hello,

Yes, I want pseudo values in UTM zone 10 projection.
I guess I could make a table of meridians and use tmerc instead.

Peter

> That lat, long is in zone 7.  You are trying to get a psuedo-zone 
> value, 3
zones away.
>


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