[sac-forum] Re: Format of GPS Input Values

Thanks Robert.  I am well aware of the UTM coordinate system, as that is
what we used in the military for plotting bomb drops.

Thomas Hilton

-----Original Message-----
From: sac-forum-bounce@xxxxxxxxxxxxx [mailto:sac-forum-bounce@xxxxxxxxxxxxx]
On Behalf Of Robert Parks
Sent: Tuesday, November 14, 2006 10:57 AM
To: sac-forum@xxxxxxxxxxxxx
Subject: [sac-forum] Re: Format of GPS Input Values
Importance: High

Tom
I am using 6.0.1.  You have to be careful and know your zones if looking for
anything other than Geographic coordinates. Maricopa County is in UTM zone
12, AZ State Plane Central, up to the west side of Maricopa County.  Then it
is AZ State Plane West to the CA border. UTM goes by longitude in 6 degree
segments, UTM Zone 12 is -108 to -114 Zone 11 is -114 to -120.

If you stick to Geographic, use NAD 83,  leave the NADCON VERTCON GEOID to
defaults. NADCON converts between old & new horizontal coordinates systems,
Vertcon converts old & new elevation systems,& the Geoid is useful & should
be set to 02 or 03, the newer the better, it projects the ellipsoid GPS
height to closer to the ground. Depending on where you are, the ellipsoid
could be above or below the ground.

Thanks,

Robert G. Parks
Vice President
Aerial Mapping Company, Inc.

602-263-5728 voice
602-263-0165 fax

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