[Proj] ToWGS84 for Germany, NRW?
Jean-Claude REPETTO
jrepetto at free.fr
Thu Oct 15 07:26:05 PDT 2009
Bytechanger a écrit :
> Hi,
>
> I want to convert 4326 to 31466....
> But there is a difference of 50m !!
>
> I think I need right +towgs84 for Germany , NRW, Rhein-Erft-Kreis ??
>
Hello,
PROJ.4 already contains the +towgs84 parameter :
cs2cs -v +init=epsg:31466
# ---- From Coordinate System ----
#Transverse Mercator
# Cyl, Sph&Ell
# +init=epsg:31466 +proj=tmerc +lat_0=0 +lon_0=6 +k=1 +x_0=2500000 +y_0=0
# +ellps=bessel +datum=potsdam +units=m +no_defs +towgs84=606.0,23.0,413.0
#--- following specified but NOT used
# +ellps=bessel
# ---- To Coordinate System ----
#Lat/long (Geodetic alias)
#
# +proj=latlong +datum=potsdam +ellps=bessel +towgs84=606.0,23.0,413.0
If it is not correct, you can find other ones in the EPSG database :
http://www.epsg-registry.org/
For my ttMaps software, I have used:
+towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.70
BTW, when you ask such a question, it is always better to give an
example (input coords, output coords, expected coords).
Jean-Claude
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