When running 'epsg_tr.py -wkt 3857', gdal produces the WKT listed below.
I believe the projection that is stated in the WKT is incorrect though.
The combination of WGS 84 as base geogcs with Mercator_1SP as projection
means that the regular ellipsoidal Mercator projection will be used
which is not correct for web mercator.
In the EPSG database 3857 is defined as using the projection 'Popular
Visualisation Pseudo Mercator' projection which is distinct from the
regular mercator projection. It's equivalent to 'apply spherical
mercator to ellipsoidal coordinates'. To indicate this distinction in
the WKT I think the projection should be something different than
'Mercator_1SP'. Mercator_1SP_Spherical, Mercator_1SP_Google or
Popular_Visualisation_Pseudo_Mercator for instance.
Is my understanding of this correct?
Pepijn Van Eeckhoudt
PROJCS["WGS 84 / Pseudo-Mercator",
GEOGCS["WGS 84",
DATUM["WGS_1984", SPHEROID["WGS
84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4326"]],
PROJECTION["Mercator_1SP"],
PARAMETER["central_meridian",0],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["X",EAST],
AXIS["Y",NORTH],
AUTHORITY["EPSG","3857"]]
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