[Proj] Using EPSG codes with cs2cs (the one who asked: Amro_rt_rps)

[Mohammad Amro]

That's brilliant Mikael ... Thanks for your support all the way.

As per your advice, after communicating withGeobasisinformation
und Vermessung Sachsen(GeoSN), they informed me that "The TRANS_SN_Light-Tool only converts coordinates from RD83_3GK (projected Gauss Krüger-coordinates) to ETRS89_UTM (projected UTM-coordinates)". As you thought :)

They guided me to an easy Java based online tool at http://gdz.bkg.bund.de/web_koordtrans/start.html. 

This service is provided by Bundesamt für Kartographie und Geodäsie (http://www.bkg.bund.de/DE/Home/homepage__node.html__nnn=true).

This tool gave same results as Proj.4 and run online. A data file can be processed too.

Best regards,
Mohammad
 

________________________________
 Von: Mikael Rittri <Mikael.Rittri at carmenta.com>
An: Mohammad Amro <ec_eng01 at yahoo.com>; PROJ.4 and general Projections Discussions <proj at lists.maptools.org> 
Gesendet: 12:18 Dienstag, 15.Mai 2012
Betreff: RE: [Proj] Using EPSG codes with cs2cs (the one who asked: Amro_rt_rps)
 

 
Mohammad, 
 
I’m starting to think that the long/lat of your
black-box tool is not WGS84 long/lat, but DHDN long/lat. 
 
The DHDN long/lat has EPSG code 4314, and DHDN /
3-degree Gauss-Kruger zone 4 
has EPSG code 31468, and I get:
 
> cs2cs +init=epsg:4314
+to +init=epsg:31468
 
13.755944 51.0545555
 
4623099.53      5659041.38
0.00
 
Here, the default datum shift that Proj.4 uses for
DHDN is not important, since both
the source and target uses the DHDN datum. The result is only 1.46 m from your
tool result. Close, but no cigar. At least you can use a smaller Finagle’s
constant ;-) 
(“That quantity which, when multiplied by,
divided by, added to, or subtracted from the 
answer which you got, yields the answer you should
have gotten.”) 
 
I don’t know if DHDN long/lat is often used for
German GIS data. The analogous thing
in Sweden 
would be RT90 long/lat, a format that you never see for GIS data, at least not
from the Swedish
 Land Survey. But the practice in
 Germany may be
different, of course.
 
> … until as you said the 2012 new modifications come to
Proj.4.
 
I don’t think they will help you. I think they are identical
to the current definitions, except
in the axis order and axis abbreviations. This is important in certain GIS
standards from
OGC for transmitting coordinates on the web, but not for you. (Since your
problem is not
that you have confused northing with easting.) 
 
> One last question to all, how do I revers the conversion from
X/Y Cartesian to Long/Lat Geographical?
 
When you use cs2cs on the command line, the “left hand side”
is everything
between cs2cs and +to, while the “right hand side” is everything
after +to. 
Just exchange the left and right hand sides to reverse the
direction. 
 
Best regards,
 
Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com
 

________________________________
 
From:proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Mohammad Amro
Sent: Wednesday, May 09, 2012 2:06
PM
To: proj at lists.maptools.org
Subject: Re: [Proj] Using EPSG
codes with cs2cs (the one who asked: Amro_rt_rps)
 
Hi all,
 
[ - text
deleted - ]
 
… may be there is no better way to do it than
offsetting the different and be happy with that. May be the tool I am using
(closed box) is following different methods for conversion?!    
 
e.g., Long: 13.755944, Lat: 51.0545555
 
Tools coordinates:
4623100   
5659040
 
7-parameters (X is shifted: 118 m, and Y is shifted 140 m)::
4623218.84   
5659181.12
 
BETA2007 Datum shifts (X is shifted: 120 m, and Y is shifted 140 m):
4623220.44    5659181.52

Anyway, I think, as I am doing this conversion on a small scale area, then a
linear offset (-118m, -140m) would result in <±2
meters which is the best I can go with until as you said the 2012 new
modifications come to Proj.4.

One last question to all, how do I revers the
conversion from X/Y Cartesian to Long/Lat Geographical?

A huge thanks you,
Mohammad Amro
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