Hi Andrea; looks like you worked out the details with Martin. Would it
be a lot of trouble to list "Google" as the authority on this one? We
can add a static final for them to Citations if needed.
Or does this definition exactly line up to EPSG:100003 ?
Cheers,
Jody
Andrea Aime wrote:
> Hi,
> I'm here to ask if I can commit a "Google Projection" class to
> Geotools. The projection used for Google Maps is basically
> a modified EPSG:41001 ("WGS84 / Simple Mercator"), but coordinates
> have to be transformed assuming a sphere instead of an ellipsoid.
> Using the major axis as radius seems to work, thought it would
> be probably more correct to use the one of the equivalent
> authalic sphere... hard to tell since this is all reverse engineering,
> in proj they get the same effect by using these params:
> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0
> +y_0=0 +k=1.0 +units=m [EMAIL PROTECTED] +wktext +no_defs.
>
> I get a good result by using the attached class plus the following
> wkt definiton:
> 100003=PROJCS["WGS84 / Simple Mercator / Google", GEOGCS["WGS 84",
> DATUM["WGS_1984", SPHEROID["WGS_1984", 6378137.0, 298.257223563]],
> PRIMEM["Greenwich", 0.0], UNIT["degree", 0.017453292519943295],
> AXIS["Longitude", EAST], AXIS["Latitude", NORTH]],
> PROJECTION["Mercator_1SP_Google"], PARAMETER["latitude_of_origin",
> 0.0], PARAMETER["central_meridian", 0.0], PARAMETER["scale_factor",
> 1.0], PARAMETER["false_easting", 0.0], PARAMETER["false_northing",
> 0.0], UNIT["m", 1.0], AXIS["x", EAST], AXIS["y", NORTH],
> AUTHORITY["EPSG","100003"]]
>
> The attached class seems to do the trick, thought it would
> be probably much more compact if Mercator1SP could be extended
> and had a param to force the sphere version of the transform.
>
> Martin, what do you think? Just give me some hints, I'll do the
> work.
>
> Cheers
> Andrea
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