# [Proj] Polish Uklad 1965 proper definition

Maciek Sieczka werchowyna at epf.pl
Mon Oct 24 17:22:44 EDT 2005

```I compared all the benchmarks done by me and Oscar van Vlijmen for 8
input points mentioned on
http://bugzilla.remotesensing.org/show_bug.cgi?id=818 and results are
following.

Compared to Transpol, official GUGiK (Polish geodesy and cartography
service) software:

[1]
PROJ.4 stere:
mean northing difference: 4,86306 m
mean easting difference:  2,57497 m

[2]
PROJ.4 sterea:
mean northing difference: 0,00065 m
mean easting difference:  0,00137 m

[3]
Oscar's implementation of
http://www.atomnet.pl/~geodeta/2000/59text1.htm with his corrections to
the algorithm:
mean northing difference: 0,00001 m
mean easting difference:  0,00000 m

[4]
Oscar's implementation of rouss:
mean northing difference: 0,00121 m
mean easting difference:  0,00189 m

Summarizing:
1. By now, best would be to use Oscar's [3].
2. Or at least replace stere with stere, as proven by [1] and [2].

What are the chances either solution would be applied to PROJ.4 and libproj?

The other thing is the empirical correction on top of the proper Uklad
1965 mathematical formulae.

Gerald Evendeen wrote:
> Is the "correction" polynomial (PASCAL code) a datum shift or a
> correction to a projection???

I *guess* it is the correction to a projection.
http://www.geonet.net.pl/gfx/pliki/kod_korekta65.txt says, roughly:
" 1. Tranformation between a mathematical grid 1965 and and it's real
equivalent (empirical, catalogue) xyz65(teor) <=> xyz65(empir) are
accomplished by algebraic polynomials of 12th degree in the zone 5 and
of 16th degree in zones 1,2,3,4. Parameters of the polynomials were
estimated based sets of several dozens of thousands of control points -
groundwork of I + II class.."

(I hope my translation explains something)

Maciek

--------------------
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http://katalog.epf.pl/

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