[josm-dev] projection Mercator, set EPSG 3785 instead of EPSG 3857

[Tobias Wendorff]

Am 08.03.2011 13:39, schrieb Josh Doe:
 > Thus the inverse flattening that Martin mentions refers
 > to the WGS 84 datum, not the EPSG:3857 projection from
 > that datum.

Yeah, but change in this datum has big outcome on the
projection. The formular used is much more complex now.

On a sphere, you can use Pi and spherical geometry to
calculate the x/y-coordinates. On a ellipsoid, you need
"expensive" expansion in series.

Right now, OSM puts both datums on the same level, which
is wrong in geodetic use, but the error is okay for non
critical applications (1/298,257223563 = 0,0033528106 unity).