[Proj] Ukraine towgs84

[Clifford J Mugnier]

Maciek,

There is no telling if extending Polish transformation parameters into
portions of the Ukraine will yield accuracies of 1 meter or so.  Since the
details of the Soviet triangulations are not public information, there is
no way to tell if their classical chains of quadrilaterals spanned these
satellite borders or avoided the borders.  If "System 42" was computed in a
"Helmert Blocking" technique; it's possible.  However, if each satellite
country had its classical triangulations adjusted on a country-by-country
basis; then it's unlikely that there is a smooth transition of datum shift
parameters across borders.

Whoever knows the answers to this over there probably is not allowed to
give clues to such things.

Note that this type of information and data is necessary for accurate
targeting of ICBMs.  Therefore, it's a traditional secret even though the
silos are no longer manned - I think.  :-)

MANY Years ago (35+), I saw the covers temporarily opened off of the silos
for some of those silo farms in Eastern Europe and Western Asia.
Scary-looking stuff.

Cliff Mugnier
LSU

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> Maciek,
>
> Cliff Mugnier has pretty much given a complete explanation why the EPSG
database contains no transformation parameters specifically for Ukraine.
> I work for Shell and can confirm that the secrecy of geodetic parameters
in the entire former Soviet Union is a serious issue. When working there
you need to get permission from the authorities (read Secret Service) to us
any coordinate system. E.g even though we know the parameters for all the
Gauss-Kruger projection zones we generally cannot use them there.
> For the same reason the EPSG database carries no transformation
parameters for any of the coordinate systems in China.

Thanks Roel, Clifford and Oscar!

I should have expected the obscurity of Ukrainian towgs84 would be a
matter of secret service affairs.

I hope this will change sometime soon, especially that Ukraine wants to
be in Europe it seems. The situation was pretty much the same about 10
years ago in Poland.

> By the way, good work by Oscar van Vlijmen in identifiying that
> 7-parameter transformation!

Indeed, good shot. I should have checked it myself first, sorry!

I was wondering... My area of interest is at the Polish-Ukrainian-Slovak
border, the East Carpathians MAB reserve. See:
http://www2.unesco.org/mab/br/brdir/europe-n/Polandmap.htm
We are not going to lurk into Ukraine more than about 50 km in our GIS.
What would be the accuracy if I use Polish Pulkovo->WGS84 7par shift,
which is well known and very accurate for Poland, for the Ukrainian and
Slovak MAB parts as well? I would be happy to have about 1m.

Maciek


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