Failure on Re: [GRASS-user] Help: Converting a raster map between locations (from wgs84 lat / long to UTM)

Hamish hamish_b at yahoo.com
Sun Nov 2 05:56:02 EST 2008


Alex Mandel wrote:
> Even though the projection is not defined, the data still has some
> information it is WGS84 which has a datum/coordinate system so you do
> need to define it, the EPSG code is 4326.
> 
> You can't reproject something from nothing, it needs at least a
> coordinate system, otherwise it doesn't know what point on your current
> map should be moved and to where it should be moved.
> 
> When you configured your first location you should have specified the
> EPSG as 4326.

right,

"They are in geodetic coordinate system (not projected, i.e., 'GEOGRAPHIC'
or 'LATLONG' system). The datum is WGS84."
   -- http://www.worldclim.org/format.htm


by "projected" they mean "not a grid system", they do not mean "without
specific georeferencing".

technically speaking lat/lon is not actually "projected" onto any plane.
it is just that it has come into common language to call any SRS a
projection, even when it is lat/lon.


so Alex is right, just use plain old lat/lon WGS84  epsg:4326 and be happy
it is not like Google Maps mercator-on-perfect-sphere.


Hamish



      



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