[GRASS-user] m.proj transformation to EPSG3785 / KML

["Peter Löwe"]

Hi Markus, hi Hamish,

thank you for your feedback and advice. The 900913-projection is a "strange beast", indeed. But it's good that GRASS allows to communicate with communities which willfully avoid everything else.

Peter 

-------- Original-Nachricht --------
> Datum: Mon, 20 Jul 2009 20:50:57 +0200
> Von: Markus Neteler <neteler at osgeo.org>
> An: Hamish <hamish_b at yahoo.com>
> CC: grass-user at lists.osgeo.org, peter.loewe at gmx.de
> Betreff: Re: [GRASS-user] m.proj transformation to EPSG3785 / KML

> On Mon, Jul 20, 2009 at 8:16 PM, Hamish<hamish_b at yahoo.com> wrote:
> ...
> > FWIW & AFAIK, KML takes coordinates as wgs84 LL, and the "Google
> > projection" is a highly dubious beast that should be avoided if
> > at all possible.
> 
> Yes!
> See also comment here:
> http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::3857
> "<remarks>
> Uses spherical development of ellipsoidal coordinates. Relative to an
> ellipsoidal development errors of up to 800 metres in position and 0.7
> percent in scale may arise. It is not a recognised geodetic system:
> see WGS 84 / World Mercator (CRS code 3395).
> </remarks>
> "
> 
> The error is significant for many GIS applications.
> 
> Markus

-- 
Dr. Peter Löwe
<peter.loewe at gmx.de>





Neu: GMX Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate
für nur 19,99 Euro/mtl.!* http://portal.gmx.net/de/go/dsl02