[GRASSLIST:6210] reprojection query

Roy Sanderson R.A.Sanderson at newcastle.ac.uk
Fri Mar 18 10:02:35 EST 2005


Hello Grass-people

I'm having a few problems reprojecting from lat-lon into Lambert Azimuth
Equal area using r.proj (or s.proj).  The reprojected lat-lon maps look
correct in terms of the shapes of the countries (various maps of Europe),
but are offset by about 1000km from where I would have expected.  I'll
admit that I don't know a lot about map projection systems, so I may have
incorrectly configured the PROJ_INFO files.  r.proj seems to work normally,
giving no strange error messages.  Using grass5.4, the g.projinfo gives the
following:

For the lat-lon:
-----------------------------------------------------------
PROJ_INFO file:	
name:	 Latitude-Longitude
datum:	 etrs89
towgs84:	 0.000,0.000,0.000
proj:	 ll
ellps:	 grs80
a:	 6378137.00000
es:	 0.0066943800
f:	 298.2572221010
-----------------------------------------------------------
PROJ_UNITS file:	
unit:	 degree
units:	 degrees
meters:	 1.0
-----------------------------------------------------------

and the Lambert AEA
-----------------------------------------------------------
PROJ_INFO file:	
name:	 Lambert Azimuthal Equal Area
datum:	 etrs89
towgs84:	 0.000,0.000,0.000
proj:	 laea
ellps:	 grs80
a:	 6378137.0000000000
es:	 0.0066943800
f:	 298.2572221010
lat_0:	 55.0000000000
lon_0:	 20.0000000000
-----------------------------------------------------------
PROJ_UNITS file:	
unit:	 meter
units:	 meters
meters:	 1.0
-----------------------------------------------------------

Any suggestions would be very helpful.
Many thanks
Roy




More information about the grass-user mailing list