Another free shapefile for world maps

[Huddleston, John]

Arlindo, here is a list of projections for Antartica:

$ ls Coordinate\ Systems/Geographic\ Coordinate\ Systems/Antarctica/
Australian Antarctic 1998.prj  Deception Island.prj  Pointe Geologie Perroud 1950.prj
Camp Area Astro.prj            Petrels 1972.prj

The NAD27 is North America Datum of 1927 and is, in general, not a good choice for projections of the world. The original maps that USGS created for the United States were based on NAD27 and the CLARK1866 sphere and they have been re-projected by USGS to NAD83 and the GRS80 sphere.

Projections for the world would fall into one of two categories: Geographic and Projected.

 $ ls Coordinate\ Systems/Geographic\ Coordinate\ Systems/World/
ITRF 1988.prj  ITRF 1991.prj  ITRF 1994.prj  ITRF 2000.prj  WGS 1966.prj
ITRF 1989.prj  ITRF 1992.prj  ITRF 1996.prj  ITRF 2005.prj  WGS 1972 TBE.prj
ITRF 1990.prj  ITRF 1993.prj  ITRF 1997.prj  NSWC 9Z-2.prj  WGS 1972.prj and WGS 1984.prj

and

$ ls Coordinate\ Systems/Projected\ Coordinate\ Systems/world
Aitoff (world).prj                   Flat Polar Quartic (world).prj  Sinusoidal (world).prj
Behrmann (world).prj                 Fuller (world).prj              Sphere-based
Bonne (world).prj                    Gall Stereographic (world).prj  The World from Space.prj
Craster Parabolic (world).prj        Goode Homolosine (Land).prj     Times (world).prj
Cube (world).prj                     Goode Homolosine (Ocean).prj    Van der Grinten I (world).prj
Cylindrical Equal Area (world).prj   Hammer-Aitoff (world).prj       Vertical Perspective (world).prj
Eckert I (world).prj                 Loximuthal (world).prj          WGS 1984 PDC Mercator.prj
Eckert II (world).prj                Mercator (world).prj            WGS 1984 Web Mercator (Auxiliary Sphere).prj
Eckert III (world).prj               Miller Cylindrical (world).prj  WGS 1984 Web Mercator.prj
Eckert IV (world).prj                Mollweide (world).prj           Winkel I (world).prj
Eckert V (world).prj                 Plate Carree (world).prj        Winkel II (world).prj
Eckert VI (world).prj                Polyconic (world).prj           Winkel Tripel (NGS - world).prj
Equidistant Conic (world).prj        Quartic Authalic (world).prj
Equidistant Cylindrical (world).prj  Robinson (world).prj

John

John Huddleston, PhD
Research Associate
Cooperative Institute for Research in the Atmosphere
Mail Stop 1375 @ CIRA
Colorado State University
Fort Collins, CO 80521
970-491-8602

From: arlindo.dasilva at gmail.com [mailto:arlindo.dasilva at gmail.com] On Behalf Of Arlindo da Silva
Sent: Thursday, November 12, 2009 8:36 AM
To: Huddleston, John
Cc: gradsusr
Subject: Re: Another free shapefile for world maps

On Thu, Nov 12, 2009 at 9:05 AM, Huddleston, John <Huddleston at cira.colostate.edu<mailto:Huddleston at cira.colostate.edu>> wrote:
Arlindo,

Please excuse this direct email to you, the GrADS email list does not allow me to reply or send anything to the list.

I downloaded the world.tar.bz2 file and it does not contain a PRJ file. While the three DBF, SHP, and SHX files conform exactly to the ESRI 1994 shapefile standard; the accuracy and precision of our software has increased significantly since the standard was propagated.

As such, it is important to know the projection of the world maps.

You may need to contact the data producers directly about this, it should be a simple matter to add a standard .prj file. However, on the website it says:

The data is based upon a free map published by TerraSpace, Russia<http://www.terraspace.ru/> as referenced by Geocommunity<http://data.geocomm.com/editorspicks/data_world11.html>. I added Antarctica after Curt Mills pointed out that there was a missing continent. Antartica's data came from the Digital Chart of the World and was reprojected into NAD27 to agree with the rest of the world.

I am not sure what NAD27 is, but I was assuming it was a standard projection. Let me know if you find anything.

         Arlindo

--
Arlindo da Silva
dasilva at alum.mit.edu<mailto:dasilva at alum.mit.edu>
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