Re: [Mapbuilder-proj] Google Map projection and EPSG codes

[Craig B. <cs...@cu...>]

"Kralidis,Tom [Burlington]" <Tom...@ec...> wrote:

> Question: has there been any definition of an EPSG code as applied to
> the way Google Maps displays their data (I'm not exactly sure what the
> projection params, but I did find one def from the postgis-users mailin=
g
> list [see:
> http://postgis.refractions.net/pipermail/postgis-users/2005-November/00=
9
> 920.html])? =20
>
> I'm not sure if CubeWerx has defined one in the 42xxx series of
> 'defacto' EPSG codes, or whether it's defined already, for that matter.

The closest match we have found is a simple Mercator projection.  One is
defined in the OGC 41xxx space as:

EPSG:41001:

PROJCS["WGS84 / Simple Mercator",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS_1984",6378137,298.257223563]],
        PRIMEM["Greenwich",0],
        UNIT["Decimal_Degree",0.0174532925199433]],
    PROJECTION["Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",0],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["Meter",1]]

This doesn't appear to be an exact match, however, as the mismatch grows
from the equator from zero to a few kilometers.  There might be a scale
factor/secant involved.

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---
Dr. Craig S. Bruce        | Ph 819-771-8303 x205 |             CubeWerx I=
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