Path: utzoo!attcan!uunet!olivea!apple!bbn.com!landheim
From: landheim@bbn.com (Greg Landheim)
Newsgroups: comp.graphics
Subject: Re: X=525120,Y=893580 map coordinates
Message-ID: <61037@bbn.BBN.COM>
Date: 21 Nov 90 14:55:28 GMT
References: <1990Nov20.142756.1109@vax5.cit.cornell.edu> <36117@cup.portal.com>
Sender: news@bbn.com
Reply-To: landheim@spcwsa.bbn.com (Greg Landheim)
Organization: Bolt Beranek and Newman Inc., Cambridge MA
Lines: 23

In article <36117@cup.portal.com> truett@cup.portal.com (Truett Lee Smith) writes:
>If those coordinates are from a map like I had to generate some years ago,
>they are in meters from a reference longitude and the equator for a trans-
>verse Mercator projection, which is what the metric military maps use.  So
>you have to know the reference longitude, whether or not the equator or some
>other crossing latitude is the zero in that direction, and the reference
>geoid to do the calculations.  Turns out to involve elliptic integrals of
>standard form which can be found in the tables.  Look in a book on the 
>subject of "geodesy" for the details.
>
>Truett Smith, Sunnyvale, CA
>truett@cup.portal.com  OR  truett@tdd.sj.nec.com

I sent a direct email response to the originator of this question and
suggested they were probably State Plane coordinates.  I forgot that
there is the system you are referring to.  If the coordinates are in
feet, they are probably State Plane.  If meters, then they are probably
in the system you are referring to.  In the first case, any standard
surveying book will give the equations and tables.  In the second case,
a geodesy text will probably have the answer.  In either case, USGS
can provide the information.

Greg