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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | RE: GISList: Projections for a specific area |
| Date: |
11/09/2002 09:21:36 PM |
| From: |
Dimitri Rotow |
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>
> Aaaahh projections. Something of a sticky subject to most.
>
> I'm looking for a projection to use to represent an area, roughly 800 to a
> 1000km. I was thinking of something like Albers or Lambert. They need to
> get good area representation with this projection. The current
> datum is WGS
> 84 and they're using Transverse Mercator, which I know is wrong as it
> squashes the data.
>
How about that? Two postings back to back asking about equal area
projections! To (mostly) repeat my answer to an adjacent thread...
I'd recommend the Lambert Azimuthal Equal Area (LAEA) projection centered on
the region of interest. As its name indicates, the LAEA is a true equal
area projection.
For a useful guide to choosing projections, see the relevant topics in the
online version of the Manifold 5.00 user manual at
http://exchange.manifold.net/manifold/manuals/5_userman/mfd50General_Project
ions_Concepts.htm
and
http://exchange.manifold.net/manifold/manuals/5_userman/mfd50Guide_to_Select
ing_Map_Projectio.htm
The above material includes some passages taken literally word for word from
"Map Projections Used by the U.S. Geological Survey," Geological Survey
Bulletin 1532, Second Edition, John P. Snyder, 1982, and also from "An Album
of Map Projections," U.S. Geological Survey Professional Paper 1453, by John
P. Snyder. These books are in print at USGS, are cheap, and should be in
the library of everyone working with projections. The first is a bit on the
mathematical side while the second one is more popular and has great
illustrations.
Cheers,
Dimitri
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