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 <[EMAIL PROTECTED]> 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
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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: [EMAIL PROTECTED]
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