[Proj] google KML API advice sought

Jan Hartmann j.l.h.hartmann at uva.nl
Fri Nov 28 06:06:54 EST 2008

Roger Oberholtzer wrote:
 > what might be a good choice for the generic projection to use that >
 > would do this best in proj (I am still using 4.4.9...)?

Hi Roger,

Just an aside, if possible, upgrade to the latest version of PROJ 
(4.6..) or you'll come to grief over datum shifts. Can't you use the 
projection Google uses itself for its maps (+proj=merc +a=6378137 
+b=6378137  +lat_ts=0 +lon_0=0 +k=1.000000 +x_0=0 +y_0=0 +units=m 
no_defs +nadgrids=@null)? This is a spherical Mercator projection based 
on the WGS84 Datum. You need to apply a correction to compute real 
distances, as Mercator maps get distorted towards the North/South Poles, 
but that is a very simple formula I believe.


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