[Proj] cs2cs: Gauss-Krüger to WGS84

[Hermann Peifer]

On 2012-12-10 12:28, Martin Trautmann wrote:
>
> Hm, I thought I got the latest release Rel. 4.8.0, 6 March 2012
> - but mine does show
> # DHDN / 3-degree Gauss-Kruger zone 4
> <31468> +proj=tmerc +lat_0=0 +lon_0=12 +k=1 +x_0=4500000 +y_0=0
> +datum=potsdam +units=m +no_defs  <>
>

Just to mention that PROJ Rel. 4.8.0, 6 March 2012 expands datum=potsdam 
to ellps=bessel and towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7

IIRC: in earlier PROJ versions, the towgs84 values for datum=potsdam 
were different. In order to be on the safe (and slightly more accurate) 
side, I prefer to use:

+ellps=bessel +nadgrids=path/to/BETA2007.gsb  [1]

Hermann

[1] http://crs.bkg.bund.de/crseu/crs/descrtrans/BeTA/de_dhdn2etrs_beta.php