[Proj] old german topo
werchowyna at pf.pl
Fri Jul 23 19:20:13 EDT 2004
From: "John Smart" <john.smart at caris.com>
> Here are the results of a couple of test runs of the proj program, using
> Gauss-Krueger projection and Bessel ellipsoid, zone 5:
> Looks like pretty reasonable correspondence to what's on your map.
> Gauss-Krueger zone 5, central meridian 15 east, false easting 5500000,
> scale factor = 1.
Thanks! I tried it and appears allright. I registered the Mestichblatter map
using Grass 5.3 into the projection above with all the grid crossings (121
points), exported into tiff/tfw, reprojected into the Polish "System 92"
(tmerc on GRS80) using gdalwarp and imported it into Grass mapset with a
"System 92" 1:10000 topo.When the Mestichblatter is displayed over the
"System 92" map it looks quite in sync but there are differences of about
3-15m in the location of even churches and few other buildings which I
don't suppose to have moved. I can't see a clear tendency in these
they are in different directions. Do you think the projection used may not
be the proper one? Or maybe I expect too much? I mean the map was prepared
in '30s and it's only 1:25000 so it can't be any more accurate propably (?).
As to the datums I tried 3 different ones and I'm not sure which one is
really suitable here. I believe I had a best result with the first of the
mentioned below. Though the reprojection result was very similar in each
case (max 1-2 m difference) I would like to know which one is right if
somebody can tell me.
taken from the
DE_DHDN / GK_3 -> Transf. -> DE_DHDN (Middle) to ETRS89
2. +towgs84: 597.1,71.4,412.1,0.894,0.068,-1.563,7.58
GRASS 5.3, datum: potsdam
GDAL 1.2.0, potsdam bessel, Potsdam Rauenberg 1950 DHDN
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