[GRASSLIST:325] Re: GRASS and the Norwegian coordinate systems (NGO48)

[Roger Bivand]

On Mon, 9 Jun 2003, Lars Forseth wrote:

> Hello list!
> 
> Can any of you answer me on this: Is it possible to use data in the Norwegian 
> coordinat system NGO48 (national grid for Norwegian maps, scale 1:1000 > 
> 1:5000 in GRASS 5.x. (Maps from 1:50.000 and greater are normaly in UTM and 
> either Ed50 or WGS84/Euref89 - so no problem with those)). The system is 
> based on a Gauss-Krueger (Transversal Mercator) projection with a datum at 
> Oslo, based on a modified Bessel ellipsoid. Coordinates are x,y and z. X is 
> north-south (always positive), Y is positive towards east along the 58 
> degrees (latitude?), so we have negative cordinates West of Oslo. The system 
> operates with 8 axes (I-VIII).
> 

If you look in the PROJ4 documentation, and look for a file for either 
ESRI or EPSG, and search for Oslo, you get some references that look 
familiar:

# NGO 1948 (Oslo)
<4817> +proj=longlat +a=6377492.018 +b=6356173.508712696 
+towgs84=278.3,93,474.5,7.889,0.05,-6.61,6.21 +pm=oslo +no_defs  no_defs 
<>

for the longlat, 

# NGO 1948 (Oslo) / NGO zone I
<27391> +proj=tmerc +lat_0=58 +lon_0=6.056250000000003 +k=1.000000 +x_0=0 
+y_0=0 +a=6377492.018 +b=6356173.508712696 
+towgs84=278.3,93,474.5,7.889,0.05,-6.61,6.21 +pm=oslo +units=m +no_defs  
no_defs <>

and so on for the other zones. I don't know if this is precise enough, 
though.

Roger

>  
> -----------------------------------------------
> Lars Forseth
> Nord-Trøndelag Fylkeskommune
> County Council of N-Troendelag
> http://folk.uio.no/forseth
> ------------------------------------------------
> 
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no