[OSRS-PROJ] gauss-krueger/transverse mercator

[Markus Neteler]

Hi Andreas,

maybe not an answer for your question, but of general
(European) interest: I convert with following calls:

Rechtswert Hochwert -> Lat Long

proj -I +proj=tmerc +a=6377397.1550000003 +es=0.0066743720\
  +lat_0=0.0000000000 +lon_0=$bezug +k=1.0000000000 +x_0=$ans +unfact=1.0000000000

where $bezug=meridian (degree, example: 9)
and   $ans= False Easting (example: 3500000)

Example:
In:  3560000 5700000
Out: 9d51'46.414"E   51d25'57.97"N

-------------------------------
Reverse transformation:
Lat Long -> Hochwert Rechtswert (y x)

proj +proj=tmerc +a=6377397.1550000003 +es=0.0066743720 +lat_0=0.0000000000\
     +lon_0=$bezug +k=1.0000000000 +x_0=$ans +unfact=1.0000000000

where $bezug=meridian (degree, example: 9)
and   $ans= False Easting (example: 3500000)

Example:

In:  9d51'46.414"E   51d25'57.97"N
Out: 3560000.01      5699999.99

Using your example I get (note: reverse order):
10.5W 29.27N
1585979.82      3402162.10

I am not shure if it is defined in southern hemisphere (but why
not, at least numerically)?

Best wishes
   Markus

On Mon, Jun 12, 2000 at 01:43:19PM +0200, Andreas Lange wrote:
> Hi,
> 
> i have a problem with the transverse mercator projection (Gauss-Kruger
> Projection) only indirectly connected to proj4.
> 
> I am writing a program for data exchange with garmin gps receivers,
> which give the position always in lat/lon wgs84, even if the receiver
> itself displays position and waypoints in 'german grid' coordinates
> (transverse mercator projection). I know that german grid here for
> germany uses 3 degree wide meridian stripes (0d, 3d E, 6d E etc.), adds
> a false easting of 500000 and prefixes the zone (0, 1, 2, 3, etc). 
> 
> But what on the southern hemisphere? Is there a constant false northing
> of 10000 m added as with UTM? The receiver displays only "----", so that
> i assume it is not defined for southern hemisphere. 
> 
> What with western longitudes? What with two-digit zones?
> 
> The receiver gives me the following readings:
> lat    lon     easting/northing
> 29.27N 10.5W   5436500/5815100 (??)
> 29.27N 10.5E   4354200/3240000 (ok)
> 29.27N 18.83E  5579200/1675000 (??)
> 29.27N 18.83W  5923300/9718000 (??)
> 85.44N 18.83E  5009100/0035000 (??)
> 85.44N 18.83W  5923000/9718000 (??)
> 
> Are those values (??) only an internal overflow of the receiver?
> 
> Thank you in advance for any hints,
> 
> Andreas Lange
> 
> -- 
> Andreas Lange, 65187 Wiesbaden, Germany, Tel. +49 611 807850
> Andreas.Lange at Rhein-Main.de, A.C.Lange at GMX.net
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