# [OSRS-PROJ] PROJ4 and Krovak projection (Czech Republic)?

Thomas Flemming tf at ttqv.com
Wed Apr 3 12:35:59 EST 2002

```Hi Markus,

last year I asked the same question, because we need this projection in
our GPS-Software.
I've got no answer, so I figured it out myself. It works, but I'm not
sure, if it is really correct integrated in proj.4.
For me, it is still very hard, to understand, how proj works. Anyway,
this is not my job.

If you like, I send you the c-sourcefile for the Krovak-Projection for
Proj.4.

Thomas Flemming

Markus Neteler schrieb:
>
> Hi,
>
> I am curious if it is possible to define the Krovak projection
> in PROJ4 (finally I want to do that in GRASS).
>
> The definition is:
>  http://www.ihsenergy.com/epsg/guid7.html#1.4.3
>
> Parameters:
>        Ellipsoid Bessel 1841 a = 6377397.155m 1/f = 299.15281
>          then e = 0.081696831 e2 = 0.006674372
>        Latitude of projection centre (j_c) 49° 30'00" N = 0.604756586 rad
>        Longitude of Origin 42° 30'00" East of Ferro
>        Longitude of Ferro is 17° 40'00" West of Greenwich
>        Longitude of Origin (l_c) 24° 50'00" East of Greenwich=0.433423431 rad
>        Latitude of pseudo standard parallel (j_1) 78° 30'00" N
>        Azimuth of centre line (a_c) 30° 17' 17.303"
>        Scale factor on pseudo Standard Parallel (ko) 0.99990
>        Easting at projection centre (Ec) 0.00 m
>        Northing at projection centre (Nc) 0.00 m
>
> Projection constants:
>          B = 1.000597498
>          A = 6380703.61
>          g 0 = 0.863239103
>          t0 = 1.003419164
>          n = 0.979924705
>          r0 = 1298039.005
>
> It might be also called "S-JTSK Ferro Krovak".
>
> As being only experienced a bit with Transverse Mercator, I am a bit
> lost with this Krovak projection.
>
> Thanks in advance for any hint (or a proj command line...)
>
>  Markus Neteler
>
> PS: There is also another description with all history:
>     http://www.asprs.org/asprs/resources/grids/index.html
>     -> The Czech Republic
> ----------------------------------------
> PROJ.4 Discussion List
> See http://www.remotesensing.org/proj for subscription, unsubscription
> and other information.

--

****************************************
**   Dipl.-Ing. Thomas Flemming
**      Software Development
**  thomas.flemming at touratech.de
**          tf at ttqv.com
**      http://www.ttqv.com
**
** ... und immer dem Pfeil nach!
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