[OSRS-PROJ] PROJ.4 "proj=latlong ellps=GRS80" functionality?

Frank Warmerdam warmerdam at pobox.com
Tue Aug 7 09:40:10 EDT 2001

Ed McNierney wrote:
> I'm having a hard time understanding how this functionality is supposed
> to work.  I've built PROJ 4.4.3 with no troubles (Windows 2000,
> Microsoft VC++) and everything seems to be working.
> I don't understand the results I'm getting from "proj=latlong
> ellps=GRS80", however.  I'm ultimately trying to use this in MapServer,
> where I have several input data layers in NAD83 decimal degrees that I'm
> trying to project to UTM.
> Here's the simple example I don't understand:
> C:\>proj -v +proj=latlong +ellps=GRS80
> #Lat/long (Geodetic)
> #
> # +proj=latlong +ellps=GRS80
> -71 43
> -1.24   0.75
> That is, my input coordinate (-71, 43) is transformed to (-1.24, 0.75).
> What does this mean?  I would expect the output results to be either
> identical to my input (if the input data is presumed to be in the output
> ellipsoid or if GRS80 or WGS84 is the default) or I would expect them to
> be very slightly different (if the input ellipsoid is something else).


As suggested the coordinates are being returned in radians; however, this
isn't the desired behaviour.  It should just returned them, reformatted,
in DMS or decimal degrees without any change to the value.  I have submitted
a bug in bugzilla on this issues. 

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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