[Proj] Accuracy Cassini Solder -> lat lon 200m?!
schubert.seb at googlemail.com
Mon Jul 6 05:27:09 EST 2009
* On Friday 03 July 2009, 11:39:31, Jean-Claude Repetto wrote:
> Sebastian Schubert a écrit :
> > I want to convert from Solder system used in the city of Berlin
> > (EPSG:3068) to the standard lat lon system.
> What do you mean "standard lat lon system" ? If you mean WGS84, you
> should try :
> cs2cs -v +init=epsg:3068 +to +init=epsg:4326
I would like to understand this a bit more. I know this is probably not
the perfect place to ask but I do not know where to ask. I would be
also very happy to be given a hint where to find the solution myself.
As far as I understand, the standard settings, I applied before:
schubert at linux-8ubn:~> cs2cs -v +init=epsg:3068
# ---- To Coordinate System ----
#Lat/long (Geodetic alias)
# +proj=latlong +datum=potsdam +ellps=bessel +towgs84=606.0,23.0,413.0
refer to the EPSG::6314 Deutsches Hauptdreiecksnetz. The not vanishing
values of towgs84 show that this is not wgs84. This gives the same
results as the formulas found in the epsg guide
when using the parameters for the ellipsoid given in the epsg database
for EPSG::6314 Deutsches Hauptdreiecksnetz.
However, I thought that when I replace these parameters with the ones of
wgs84, I should actually get wgs84 coordinates. This does not seem to
be true. Does this mean that eg the ellipsiod has another centre? So
the formulas given in the guide are only applicable for exactly one
Base Geodetic CRS (in this case DHDN)? So proj does a two step
conversion when I want to convert to wgs84: convert to Base Geodatic
system, then convert to wgs84? Are the formulas for the latter given
Thanks a lot!
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