ToWGS84 for Germany, NRW?

[Bytechanger]

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 ??

Greetings

Byte

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[Milo van der Linden-2]

Byte,

Do you have the proj string or the EPSG code for the projection you use
natively in Germany? I think it is needed to see what ellipsoid/spheroid
is native to you to determine the +towgs84 transformation.

Bytechanger schreef:

> 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 ??
>
> Greetings
>
> Byte
>
> _______________________________________________
> Proj mailing list
> [hidden email]
> http://lists.maptools.org/mailman/listinfo/proj
>
>  

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[Kristian Thy]

On Thu, Oct 15, Milo van der Linden wrote:
> Bytechanger schreef:
> > I want to convert 4326 to 31466....
>
> Do you have the proj string or the EPSG code for the projection you use
> natively in Germany? I think it is needed to see what ellipsoid/spheroid
> is native to you to determine the +towgs84 transformation.

I would hazard a guess that he's trying to convert from EPSG:4326 to
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

\\kristian
--
... et nemo ex vobis interrogat me: »Quo vadis?«
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[Schmitz, Uwe]

Byte,
>
> 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 ??
>
for this area you can try:
+towgs84=631,23,451

which you can find documented here:
http://www.bezreg-koeln.nrw.de/brk_internet/organisation/abteilung07_produkte/raumbezug/bezugssystem_uebergaenge/index.html

May be you have to fiddle around with the signs.

Also you can try to use the BeTA2007 NTv2-Grid
with +nadgrids which you can download here:
http://www.crs-geo.eu/nn_124226/crseu/EN/CRS__Description/crs-national__node.html?__nnn=true

Hope that helps.

Regards,
Uwe
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[Jean-Claude Repetto]

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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[OvV_HN]

----- Original Message -----
From: "Bytechanger" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, October 15, 2009 3:30 PM
Subject: [Proj] ToWGS84 for Germany, NRW?


> 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 ??
>

If in doubt about parameters, one could consult:
Bezirksregierung Köln, GEObasis.nrw
For instance, the page:
http://www.lverma.nrw.de/produkte/raumbezug/koordinatentransformation/Koordinatentransformation.htm
Scroll down to perhaps:
"Die für Nordrhein-Westfalen durchschnittlichen Shiftparameter sind in den
folgenden Tabellen aufgelistet: <Datumshiftparameter>"



Oscar van Vlijmen



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