[PROJ] Calculating DTK25 from WGS84

[Dominik Vogt]

Hi folks,

I have little knowledge of map projections and really need some
help with a coordinate transformation.

The source data is a long list of latitude/longitude pairs in
WGS84 (epsg:4326).  The goal is to calculate the corresponding
DTK25 map sheet.

DTK25 is a four digit number XXYY where

  XX = [(56 - lat) * 10]
  YY = [(lon - 5.66666666) * 6]

*But* DTK25 is based on the bessel ellipsoid.

What I cannot figure out is how to transform the latitude and
longitude from the wgs84 ellipsoid form to the bessel ellipsoid
form.  I've tried something like this:

  echo 49.12345 8.55555 |
  cs2cs +proj=latlon +ellps=WGS84 +to +proj=latlon +ellps=bessel -f "%.12f"

But it actually does nothing; output coordinates are unchanged.
Maybe I just don't understand how cs2cs works.

Ciao

Dominik ^_^  ^_^

--

Dominik Vogt