[GRASS5] GRASS 5.3/5.7, GDAL and southern hemisphere

[Hamish]

> > To summarise: this inconsistency could be fixed either in r.in.gdal
> > or g.setproj and I'm not sure which would be more appropriate as I
> > don't understand the significancy of being in the southern
> > hemisphere for the UTM projection. Maybe somebody could explain
> > this.
> 
> Maybe Hamish can help?

The difference is that UTM quadrants in the Southern Hemisphere have a
false northing of 10,000,000. This is to prevent the possibility of
negative map coordinates.



Hamish

p.s.-
If it is any use, the following Matlab (or gpl'd Octave) script 
will tell you what UTM zone you are in for a given [lat lon].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% utm_zone.m    Calc UTM zone from Lat/Lon position.
%%  Hamish Bowman, mid 2002 sometime
%
% UTM is based on a Transverse Mercator (conformal, cylindrical) projection.
% 60 zones. Width 6deg lon, numbered 1 to 60, starting at 180deg lon (West).
%  8deg lat strips, C to X northwards, omitting I and O, beginning at 80deg
%  South.
%
% Panama: Clark1866, NAD27
% Zone: 

% West is negative, south is negative
if (exist('LatLon') ~= 1)
        LatLon = [7.871289533  -81.6107378 ]
end

Strips = [ 'C' 'D' 'E' 'F' 'G' 'H' 'J' 'K' 'L' 'M' ...
                   'N' 'P' 'Q' 'R' 'S' 'T' 'U' 'V' 'W' 'X'];

Zone = ceil((LatLon(2)+180)/6)
Strip = Strips(ceil((LatLon(1)+80)/8))