Uploaded by: http://crschmidt.net/
The commonly described 'Google Projection'. The trick here is the nadgrids=@null. Much much much help to sharpgis for his help on figuring this out:
+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 +no_defs
(The proj4 output here does not export the '+nadgrids=@null'.)
- http://spatialreference.org/ref/user/6/
- Human-Readable OGC WKT
- Proj4
- OGC WKT
- GML
- ESRI WKT
- USGS
- MapServer Mapfile
- PostGIS spatial_ref_sys INSERT statement
Comments
#2 http://crschmidt.net/ commented, on July 23, 2007 at 10:28 -05:
Okay. In more than an hour of playing around, I finally have proj4 text that actually works:
+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 +no_defs
Many, many many, many, many, many thanks for sharpgis's help on this!
#3 http://crschmidt.net/ commented, on July 24, 2007 at 10:45 -05:
Proj4 was nabbed from http://proj.maptools.org/faq.html
#4 http://therajah.myopenid.com/ commented, on July 26, 2007 at 02:05 -05:
The WKT from this projection will not work in ESRI.
Try the one at http://spatialreference.org/ref/user/16/...
(The problem is ESRI does not understand Mercator_2SP
#5 http://therajah.myopenid.com/ commented, on July 26, 2007 at 02:22 -05:
Looking at Mercator (world) projection in ArcGIS - which I am assuming maps to the correct GoogleEarth projection - b has a value of 298.257223563, whereas yours has a value of 6378137.0. Which is correct?
#6 http://openid.aol.com/sharpgis commented, on July 26, 2007 at 03:39 -05:
Google and Live Maps both use a spherical datum, so this value is correct for the projected maps. This is what you need to use if you need to create image overlays/tiles.
HOWEVER, any coordinate input you give, is expected to be in Longitude/Latitude using WGS84.
#7 http://www.nutiteq.com/ commented, on July 3, 2008 at 02:13 -05:
This coordinate system is now also referred as EPSG:600613 . This is probably unofficial.
#8 jaak@nutiteq.com commented, on July 3, 2008 at 02:21 -05:
I meant EPSG:900913 , so this is just trans-numeration of google
#1 http://crschmidt.net/ commented, on July 23, 2007 at 09:18 -05:
sharpgis offers this:
+proj=merc +latts=0 +lon0=0 +k=1.0 +x0=0 +y0=0 +a=6378137.0 +b=6378137.0 +units=m