I have a shell script that converts Gauß-Krüger coordinates (which
are still used by some Germand botanists) to WGS 84. It looks
roughly like this:
# RW and HW contain the "Rechtswert" and "Hochwert" in GK (Potsdam
# datum)
# Figure out the source coordinate system, depending on the first digit
# of the "Rechtswert", i. e. the "Meridianstreifen":
case "$RW" in
(2*) CS="epsg:31466" ;;
(3*) CS="epsg:31467" ;;
(4*) CS="epsg:31468" ;;
(5*) CS="epsg:31469" ;;
(**) CS="epsg:31467" ;;
esac
# convert to WGS 84
echo "$RW" "$HW" |
cs2cs +init="$CS" +to +init=epsg:4326 |
read LON LAT JUNK
Now I need to do the reverse transformation. There is no obvious
way to guess the right destination coordinate system. Is there a
simpler way than just trying all four and see which one yields the
correct result?
for CS in epsg:31466 epsg:31467 epsg:31468 epsg:31469; do
echo "$LAT" "$LON" |
cs2cs +init=epsg:4326 +to +init="$CS" |
read RW HW JUNK
# if RW and HW are good, return them, otherwise try next CS
done
Ciao
Dominik ^_^ ^_^
--
Dominik Vogt
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