[GRASS-dev] Re: [GRASS GIS] #1536: add EPSG:900913 to location wizard

[GRASS GIS]

#1536: add EPSG:900913 to location wizard
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 Reporter:  timmie                   |       Owner:  grass-dev@…              
     Type:  enhancement              |      Status:  new                      
 Priority:  normal                   |   Milestone:  6.4.2                    
Component:  Projections/Datums       |     Version:  6.4.2 RCs                
 Keywords:  google projection, epsg  |    Platform:  All                      
      Cpu:  Unspecified              |  
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Changes (by neteler):

  * platform:  MSWindows XP => All


Comment:

 I would note that it is not the official code:
 {{{
 tail -3 /usr/share/proj/esri.extra
 #  Chris' funny epsgish code for the google mercator
 #
 <900913> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0
 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext  +no_defs <>
 }}}

 The fact that 900913 exists is AFAIK historically: to get +nadgrids=@null
 into a code. For subsequent history, see Hamish's comment above.

 See also:

 http://trac.osgeo.org/openlayers/wiki/SphericalMercator
 "SphericalMercator and EPSG aliases

 The SphericalMercator projection in OpenLayers uses code epsg:900913. When
 Google started to use the SphericalMercator projection, a corresponding
 EPSG
 code did not yet exist, so a temporary code '900913' (notice the
 resemblance
 to the word 'google') was invented. Many other services, such as
 OpenStreetMap,
 Bing and Yahoo are now also using the same projection, but are not
 necessarily
 supporting the use of code EPSG:900913. Other codes, such as EPSG:3857 and
 EPSG:102113 were invented. Today, there is an officially registered EPSG
 code
 3857 whose projection is identical to EPSG:900913.
 (http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::3857)."

 I would suggest to support the official code rather than the inofficial
 one
 which may disappear since superceeded.

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/1536#comment:2>
GRASS GIS <http://grass.osgeo.org>