Bill, the coordinates should in fact change. An object at a specific
location will have different lat/long coordinates in NAD27 and NAD83. It
turned out that Pete's problem here was that the initial table was in
lat/long unprojected. When you use Save Copy As on an unprojected table it
simply writes the projection to the .tab file without changing the
coordinates. If you know your coordinates are actually in NAD27, you need to
do 2 Save Copy As commands, the first to NAD27 and the second to NAD83.
_____________________________
Tim Warman
Geologist & GIS Specialist
Richard C. Slade & Associates
North Hollywood, CA
(818) 506-0418
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Bill Thoen
Sent: Friday, April 14, 2000 2:00 PM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: MI NAD27 to NAD83
What changes is the objects' actual positions on the earth, not
their coordinates. In other words (-105, 40) in NAD 83 is about
150 feet east of (-105, 40) in NAD 27. If you create a point at
this location and save it in a table with a NAD83 projection, and
then save it to another table with a NAD 27 projection, and open
both of these on the same mapper, the one that has the coordinate
at (-105, 40) will be the from your FIRST layer in your mapper.
The other gets a coordinate slightly different because it's being
displayed in a coordinate system different from its native one.
Open a new mapper with the layers reversed and the other point is
"correct". (This is because the mapper gets its coordsys from the
first map layer displayed in a mapper.)
- Bill Thoen
[EMAIL PROTECTED] wrote:
>
> All,
> I have a map in NAD27. When I "Save Copy As..." the map to another file,
> changing the projection to NAD83, all the features in the new map have the
> exact same lat,long values. I was under the impression that a feature's
> specific location in NAD27 would change a little bit in NAD83. ex: NAD27
77.5
> w, 39.0 n = NAD83 -77.4899 w, 38.889 n. Any answers?
> Thanks,
> Pete
> [EMAIL PROTECTED]
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