[Proj] Google Mercator Projection
jagoncal at gmail.com
Thu Aug 4 04:55:52 EST 2011
The formula for "Google Mercator" Y coordinate is:
6378137 * LN ( TAN ( PI / 4.0 + LAT / 2.0 ) )
For LAT=52.4827802220782 you get 6887893.49, which is what you are obtaining
The other value is some 30 km smaller. May be it was calculated with the
actual Mercator projection of the ellipsoid.
2011/8/4 zagot <maurelio at live.it>
> Hi to All,
> this is an oldie, but i cannot seem to find a solution.
> When i want to do a transform on a wgs84 to google/bing the y coordinate
> I have read this variuos post and this official note:
> ...so I tried adding +nadgrids=@null like i read, but with this example:
> from ..."+proj=latlong +datum=WGS84";
> to... "+proj=merc +a=6378137 +b=6378137 +lat_t1=0.0 +lon_0=0.0 +x_0=0.0
> +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs"
> i have this result -626172.1357121646, 6887893.4928337997
> in the result y differ from correct value:6853955.508199729 (with Proj.NET
> the result is correct)
> ..seems adding +nadgrids=@null have no effect
> what's I wrong?
> thanks in advance
> sorry for my english
> View this message in context:
> Sent from the PROJ.4 mailing list archive at Nabble.com.
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