[Proj] latlong to latlong conversion

Frank Warmerdam warmerdam at pobox.com
Wed Aug 18 15:41:09 EDT 2004

Naiara S. Pinto wrote:
> Hi folks,
> I am new to proj and I am trying to convert a file that is in
> latlong(spheroid based, GRS80) into another latlong (datum based, WGS84).
> Is that possible?
> Any tips would be greatly appreciated!


This can be accomplished with the cs2cs tool which handles a "coordinate system
to coordinate system" conversion.

For example, to convert from lat/long NAD27 to lat/long WGS84 you might do:

   cs2cs +proj=latlong +datum=NAD27 +to +proj=latlong +datum=WGS84

Note that the GRS80 and WGS84 ellipsoids are not very different and a
conversion between them without any extra datum shift information provided
will not generally result in any perceptible change.

Also, the above command is essentially for conversion of a list of x,y
pairs.  If you have a vector file or raster file, additional issues
apply, and you will need to be more specific.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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