Google Maps / Virtual Earth map projection in MapServer

[Ei Fujioka]

Hi Dave,

As long as Goolge Maps goes, I use the following mapfile (excerpt).
I'm not sure if UNITS and EXTENT should be in Mercator meters but in 
reality this works excellent.
GM's tile layer overlays served from Mapserver line up well with Google 
Maps' satellite images.

MAP
   NAME "YOUR MAPPER NAME"
   SIZE 256 256
   STATUS ON
   IMAGETYPE png

EXTENT -180 -90 180 83.6236
PROJECTION
   # Google Maps uses Mercator
   "init=epsg:54004"
END
UNITS DD
TRANSPARENT ON

Ei


Dave Weaver wrote:
> I'm trying to get my map in the same projection that's used by Google Maps &
> Virtual Earth.
> 
> According to this article:
> 
> http://www.sharpgis.net/2007/05/05/SpatialReferencesCoordinateSystemsProjectionsDatumsEllipsoidsConfusing.aspx
> 
> the SRS string for the projection used is:
> 
> PROJCS["Mercator Spheric", GEOGCS["WGS84based_GCS",
> DATUM["WGS84based_Datum", SPHEROID["WGS84based_Sphere", 6378137, 0],
> TOWGS84[0, 0, 0, 0, 0, 0, 0]], PRIMEM["Greenwich", 0, AUTHORITY["EPSG",
> "8901"]], UNIT["degree", 0.0174532925199433, AUTHORITY["EPSG", "9102"]],
> AXIS["E", EAST], AXIS["N", NORTH]], PROJECTION["Mercator_1SP"],
> PARAMETER["False_Easting", 0], PARAMETER["False_Northing", 0],
> PARAMETER["Central_Meridian", 0], PARAMETER["Latitude_of_origin", 0],
> UNIT["metre", 1, AUTHORITY["EPSG", "9001"]], AXIS["East", EAST],
> AXIS["North", NORTH]]
> 
> How can I use this information in my map file to specify the output
> projection of my map? (projections aren't my strong point!)
> 
> Thanks,
> Dave.
> 

-- 
======================
   Ei Fujioka
   Research Associate
   Duke University

   (919) 613-8021
   efujioka at duke.edu
======================