[Gvsig_english] Gvsig_internacional Digest, Vol 47, Issue 12

Sat Dec 12 19:36:03 CET 2009

Hello Juan Lucas Dominquez,

i think the coordinates in the BETA2007testdata.csv are
first class and basicly used for the grid-calculation BETA2007.gsb.

I have tried the transformation 1780 in gvSIG 1.9 again, but 
with the same bad results  ... but nobody is perfect. 

For a manual transformation from GK3 EPSG:31467 to ETRS89/UTM32N
EPSG:25832 i have found some parametersets here

   www.crs-geo.eu -> CRS Description  -> national CRS

Using the same testdata and the parameterset for the  n o r t h
of former Westgermany the errors are less 1 m. So a seven-
parameter-transformation with change of the geo-datum in gvSIG 1.9 
in general seems to work. For more details of the last test see the attachment.

By the way, what about a tool for transforming lots of shapes/rasters
in a batch-mode in future gvSIG-versions (like the batch-project tool in ArcGIS) ?  In this context a file with testdata (included in the batch stuff) is very usefull to verify the handling of the transformation. 

Greetings   

Heinz

-------- Original-Nachricht --------
> Datum: Sat, 12 Dec 2009 12:00:10 +0100
> Von: gvsig_internacional-request at listserv.gva.es
> An: gvsig_internacional at listserv.gva.es
> Betreff: Gvsig_internacional Digest, Vol 47, Issue 12

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> Today's Topics:
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>    1. Re: No problems reprojecting from GK to UTM	usingBETA2007
>       (Juan Lucas Dominguez Rubio)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Fri, 11 Dec 2009 22:47:14 +0100
> From: "Juan Lucas Dominguez Rubio" <jldominguez at prodevelop.es>
> Subject: Re: [Gvsig_english] No problems reprojecting from GK to UTM
> 	usingBETA2007
> To: "Users and Developers mailing list"
> 	<gvsig_internacional at listserv.gva.es>,
> 	<gvsig_internacional at listserv.gva.es>
> Message-ID:
> 	<E43C32BC5843E34FB4C00CDFAAAAF7D8017B4DB9 at australia.prodevelop.local>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Hello, Heinz:
>  
> I have done the test you describe and indeed the points in the CSV file
> are not a subset of the GSB grid, but the error is almost zero. If we are
> honest, we'll have to look for an explanation, no? Here is my guess: the CSV
> file was created using the GSB grid. I misunderstood the goal of that
> verification file (perhaps the Australian file too?). They are not used to check
> if the grid works fine. They are used to check that your GIS software knows
> how to deal with the grid. This is my second hypothesis :-)
>  
> As for the transformation with code 1780 available in gvSIG, I have used
> it and get the expected errors (< 5m):
>  
> 3.43 m
> 2.85 m
> 0.15 m
> etc.
>  
> Perhaps you have not chosen the right options? I have used gvSIG 1.1.2
> because I am on Windows Vista.
>  
>  
> Regards,
>  
> Juan Lucas Dom?nguez Rubio
> ---
> Prodevelop SL, Valencia (Espa?a)
> Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
> http://www.prodevelop.es <http://www.prodevelop.es/> 
> ---
> 
> ________________________________
> 
> > De: gvsig_internacional-bounces at listserv.gva.es en nombre de Heinz
> Mundhenk
> > Enviado el: jue 10/12/2009 18:07
> > Para: gvsig_internacional at listserv.gva.es
> > Asunto: Re: [Gvsig_english] No problems reprojecting from GK to UTM
> usingBETA2007
> > 
> 
> 
> > Dear list,
> > 
> > here is another working grid-based reprojektion for Germany.
> > 
> > Reprojecting from GK to ETRS89/UTM using grid BETA2007
> > 
> > In the next years coordinates from different old SRS in
> > Germany will change to the new projection ETRS89/UTM
> > with EPSG:25832 (Westgermany) and 25833 (Eastgermany).
> > 
> > Most old SRS in former Westgermany are based on the Gauss-Krueger-
> > Projektion (GK, EPSG:31466, 31467 and 31468).
> > 
> > The transition from GK to UTM can be done with the integrated
> > "transformation on the fly" in gvSIG for errors lower than 5 meters.
> > 
> > If you use the grid "BETA2007.gsb", the error is lower than 1 meter.
> > 
> > Here you can get the grid and coordinates for a tests :
> > 
> >   www.crs-geo.eu/BeTA2007
> > 
> >   files BETA2007.gsb (85 kByte)
> >         BETA2007testdaten.csv (12 kByte)
> > 
> > On this website you find lots of additional informations.
> > 
> > For a test make a dfb-file from the csv-file by selecting all records
> >   with Quell-Bezugssystem (source) = DE_DHDN_3GK3
> >   and  Ziel-Bezugssytem (target) = ETRS89_UTM32.
> > 
> > From this dbf-table create the shape (with testpoints)
> >   GK3_31467.shp using Quell-X and Quell-Y for X- and Y-coodinates.
> > 
> > How to integrate the *.gsb - file in gvSIG 1.9 ?
> > 
> > Make a view with SRS-property EPSG:25832 (ETRS89/UTM32) and add the
> > testpoint-shape with the SRS-Property EPSG:31467, using
> grid-transformation
> > (with german-program-surface/skin : NTv2 Format Raster- Datei).
> > In the next window click the button Import and select the
> > previous downloaded grid BETA2007.gsb.
> > 
> > Then Export the reprojected shape under the name UTM32_25832.shp and add
> it to
> > the view. Now you can add the fields X and Y and calculate x() and y().
> > Then calculate the difference between Ziel-X and X / Ziel-Y and y.
> > The Errors are lower 0.01 meters ! The testpoints are no grid-points !
> > 
> > Observations
> > 
> > 1. The reprojektion with the grid does not work in the reverse order
> >    from UTM to GK.
> > 
> > 2. Reprojection from GK to UTM with gvSIG using the same testpoint-shape
> >    and the integrated EPSG-transformations 1780 or 15948 result with
> >    errors between 100 and 200 meters !  Why ?
> > 
> > Greetings
> > 
> > Heinz Mundhenk
> > hmundhenk at gmx.de
> > 
> 
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-- 
Viele Grüße

Heinz Mundhenk

Tel. 05281 / 163742
e-mail hmundhenk at gmx.de

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