[Proj] Google Mercator Projection

Frank Warmerdam warmerdam at pobox.com
Mon Oct 15 19:24:51 EDT 2007

Christopher Barker wrote:
> Hi,
> Craig Bruce wrote:
>> I am having a problem converting coordinate values from WGS84 
>> Geographic to
>> the Mercator projection that Google Maps uses. 
> There was a fair bit of talk about this at the FOSS4G conference, I only 
> caught bits of it. This may help:
> http://crschmidt.net/blog/archives/238/understanding-googles-projection-slightly-anyway/ 
> There was talk of a new EPSG code for the google Mercator projection:
> http://crschmidt.net/blog/archives/243/google-projection-900913/


You should also read the final FAQ at:


It talks about how to stop pj_transform() from doing a big shift to get
from Mercator spherical coordinates to WGS84 ellipical coordinates.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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