[PROJ] Danish_System_34_Sjaelland

[Javier Jimenez Shaw]

Thanks!

On Tue, 15 Aug 2023 at 04:46, Thomas Knudsen <knudsen.thomas at gmail.com>
wrote:

> That definition definitely looks odd. The correct EPSG id for System 34
> Sjælland
> is 10250 (and its companion for the western part of Denmark, "System 34
> Jylland"
> is EPSG:10160).
>
> For historical reasons, those systems are utterly odd: They originated as
> cadastral
> systems, and the cadastre did not really care about the absolute
> orientation of
> the systems, hence ignoring (at that time, i.e. 1930-ish), existing
> astro-geodetic
> observations, to the effect that what was specified as a transverse
> cylinder
> projection actually ended up as oblique.
>
> Which also means, as noted by Mikael Rittri a decade ago on this mailing
> list, that System 34 can be approximated at the metre level by an oblique
> mercator
> (proj=omerc).
>
> The reconstructions we recently submitted to the EPSG, are based on
> transverse
> mercator, but use grid based datum shifts to correct for the
> mis-orientation and
> network tensions.
>
>
> Den tirs. 15. aug. 2023 kl. 00.18 skrev Javier Jimenez Shaw <
> j1 at jimenezshaw.com>:
>
>> Hi
>>
>> I got this wkt, which projection "Transverse Mercator Sjaelland" is not
>> supported by PROJ
>>
>> PROJCS["Danish_System_34_Sjaelland", GEOGCS["GCS_European 1950",
>> DATUM["D_European 1950",
>> SPHEROID["International_1924",6378388.000000,297.000000]],
>> PRIMEM["Greenwich",0.000000], UNIT["Degree",0.017453292519943295]],
>> PROJECTION["Transverse Mercator Sjaelland"],
>> PARAMETER["Scale_Factor",0.999600],
>> PARAMETER["Central_Meridian",9.000000],
>> PARAMETER["False_Easting",500000.000000], UNIT["Meter",1.000000000000]]
>>
>> Seems to be something very Danish specific, and quite old. Do you know
>> any equivalent wkt that may work in PROJ? There were some Danish grid files
>> added recently for S34
>>
>> Thanks
>> Javier
>> .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
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>
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