[GRASS-user] Import CH1903 Referenced Geodata

Massimiliano Cannata massimiliano.cannata at supsi.ch
Fri Nov 14 05:27:29 EST 2008


Answer to the first question...

1) The parameters given are for CH1903+ which is apparently different 
from CH1903 - I have no idea how much or if the differences are big 
enough to be relevant.

The difference is relevant, because the CH1903 and CH1903+ are actually 
two different reference systems.

The Geodetic office (SwissTopo) says:
"The local reference system CH1903+ with its reference frame LV95 
(Landesvermessung 1995) is derived from CHTRS95. In defining CH1903+, it 
was important that it remains as close as possible to the old reference 
system CH1903. The parameters defining the system were transferred from 
the old fundamental station (old observatory of Bern, which does not 
exist any more) to the new fundamental station in Zimmerwald. The 
reference frames LV03 and LV95 show differences of up to 1.6 metres 
because of the local distortions of LV03. These local distortions are 
modelled with a local affine transformation (program FINELTRA)"

So, I would say that the differences are relevant (at least for 
precision applications: cadaster, monitoring, etc..)

Massimiliano


Markus Neteler wrote:
> On Thu, Nov 13, 2008 at 11:15 PM, Tom Russo <russo at bogodyn.org> wrote:
>   
>> As Helmut points out, the e00 files say instead that the data is in an oblique
>> projection in meters, and looking at the shapefile data it does not look like
>> they are in CH1903/EPSG:4149 coordinates, despite the metadata saying they're
>> in CH1903.
>>     
>
> Please also note
> http://trac.osgeo.org/grass/ticket/35
> Verify and uncomment Swiss datum parameters
>
> I dunno if it related but it waits for a volunteer.
>
> Markus
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
>   


-- 
-----------------------------------------------------
Dr. Massimiliano Cannata
Environmental & Geomatic Engineer

Institute of Earth Sciences - SUPSI
Trevano, C.P. 72, CH-6952 Canobbio, SWITZERLAND

Tel:    +41 (0)58 / 666 62 14  
Fax:    +41 (0)58 / 666 62 09
E-mail: massimiliano.cannata at supsi.ch

Web: 
http://www.ist.supsi.ch
http://istgis.ist.supsi.ch:8001/geomatica/
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