[OSRS-PROJ] epsg code for swiss grid and NTF Lambert IGN

[Claude Philipona]

Franck,

> These aren't the same projection definitions as found in the EPSG tables
> (at least the EPSG 4.3 tables) which is an LCC 1SP projection with a scaling
> factor.  How did you derive your projections, and are they equivelent to
> the EPSG projections?  I am hesitant to incorporate them into the EPSG file
> without greater confidence about their relationship to the EPSG definition.

You'll find here where I found the parameters and epsg code. I waiting for your
advice on all that, but all I can says that it works quite fine (I did test quite
a few reference point; we are using extensively mapserver and proj to build an
interactive sites where peoeple will have the opportunity to georeferenced routes
for mountaineering sports in the alps, to be released soon). I know that quite a
few people were waiting for the parameters for (france, switzerland, italy,
spain, austria) for use with proj so I decided to spent a little time on it.
Don't forget to give me your advice or to propose better solution.

Tell me if you need more information

Claude

SWITZERLAND: 9814
- http://www.remotesensing.org/geotiff/proj_list/swiss_oblique_cylindrical.html
for swis oblique cylindrical where you can found the code 9814

The definitions are at the following address (in english):
http://www.swisstopo.ch/en/geo/refsys.htm

You'll find a more complete explanation "Formulas and constants for the
calculation of the Swiss conformal cylindrical projection and for the
transformation between coordinate systems" in this pdf file:
ftp://ftp.swisstopo.ch/pub/data/geo/refsyse.pdf

In these different files, they propose tu use the geocentric transformation
parameters to the european reference system ETRS89 (which is very close to
WGS84):

X(ETRS89) = X(CH1903) + 674.374 m
Y(ETRS89) = Y(CH1903) + 15.056 m
Z(ETRS89) = Z(CH1903) + 405.346 m

(without scale factor or rotations)

I tested these parameters with cs2cs, and it gave good result (usually below 1
meter)


Meilleure solution:
Prendre les parametres entre ch1903+ et CHTRS95 (qui tres proche de ETRS89 et de
WGS84)
XCH1903+ = XCHTRS95 - 674.374 m
YCH1903+ = YCHTRS95 - 15.056 m
ZCH1903+ = ZCHTRS95 - 405.346 m
which gives +towgs84=674.374,15.056,405.346

The old solution is to take the Granit Parameter (7 parameter). Granit87
parameters were used between 1987 and 1997 for the transformation between CH1903
and
WGS84. They do not recommend their use anymore:
dX = 660.077 m
dY = 13.551 m
dZ = 369.344 m
rx = 2.484 cc (centesimal seconds) = 0.804997 arcs seconds
ry = 1.783 cc (centesimal seconds) = 0.578004 arcs seconds
rz = 2.939 cc (centesimal seconds) = 0.951997 arcs seconds
s = 1.00000566 (m = 5.66 ppm)

I tried these parameters (arc seconds) with cs2cs, but it didn't give good
results. Error of up to 20 meters. I tried all the possible configuration of sign
without success.

You'll find an online pages for coordinate transformation swiss_ch1903 <-> wgs84:
http://www.swisstopo.ch/en/geo/navref.htm

FRANCE: 275xxx

Epsg number where taken from:
- http://inovagis.dcea.fct.unl.pt/giserver/epsg.asp where I found number for
france
Note that in this list there are only 27581 to 27584, with 27582 described as
NTF(Paris)/Lambert II (etendu)(etendu=extended). There is no difference between
NTF(Paris)/Lambert II (etendu)
and NTF(Paris)/Lambert II except a 2000000 shift in y_0. the "etendu" of LII
version in used to described the entire France (the digital raster map from IGN
are georeferenced in LII etendu). As I need both LII and LII etendu it seemed
more logical for me to use 27581 to 27584 for the normal zone and to add 27585
for the etendu (I don't know why there are not 2 different numberr for LII and
LII etendu).
The 27591-94 are the carto version, and represent coordinates printed on the map
(but no used for georeferencing the). It is actually the same definition as the
27581-84 execept that the number of the zone is put in front of the coordinate
written in kilometer in zone three, 254000 becomes 3254.
You'll find all the parameters describing the french system at:
http://www.ign.fr/fr/PI/activites/geodesie/coordonnees.html
(only in french, official site of the French National Geographic Institute)

You'll find also a few pdf files and software (coordinate transformation) to
download at:
http://www.ign.fr/fr/PI/activites/geodesie/rgf93/OUTILS/index.html

> Claude Philipona wrote:
> > I don't know if it might insterest somebody or if it could be
> implemented in the
> > next release of proj, but here are the epsg code for Swiss grid
> (used with swiss
> > topo map) and NTF Lambert IGN (used with IGN france topo map).
> >
> > I have tested all these configuration with reference points, and the
> result are
> > correct, with a small error below one meter for projection transform
> > (datum-shift) between swiss and france
> >
> > Claude Philipona
> >
> > # CH 1903 / Swiss Oblique Cylindrical
> > <9814> +proj=somerc +lat_0=46d57'08.66"N +lon_0=7d26'22.50"E +ellps=bessel
> > +x_0=600000 +y_0=200000 +towgs84=674.374,15.056,405.346 +units=m
> +k_0=1 +no_defs
> > <>
> >
> > # NTF (Paris) / France I
> > <27581> +proj=lcc +a=6378249.2 +b=6356515.0 +lat_0=49d30'0.0"N
> > +lon_0=2d20'14.025"E +lat_1=48d35'54.682"N +lat_2=50d23'45.282"N
> +x_0=600000.0
> > +y_0=200000.0 +towgs84=-168,-60,+320 +units=m no_defs <>
> >
> > # NTF (Paris) / France II
> > <27582> +proj=lcc +a=6378249.2 +b=6356515.0 +lat_0=46d48'0.0"N
> > +lon_0=2d20'14.025"E +lat_1=45d53'56.108"N +lat_2=47d41'45.652"N
> +x_0=600000.0





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