[OSRS-PROJ] Roussilhe Oblique Stereographic

[Gerald Evenden]

Two of Snyder's coauthored books include some information on
this projection for the forward case (geographic->cartesian) but
no information on the inverse.  Each description of the Roussilhe
is sufficiently different to make thing confusing.  Going
to the original article may be difficult for two reasons: language
and obscurity.

Snyder has his own oblique stereographic and EPSG lists another
flavor.  At the moment, libproj4 only supports Snyder's version.

As for latitude of true scale, this is usually only used in the polar
version.  k_0 is more appropriate for oblique and equatorial.

If precision is not a criteria, then I suggest using Snyder's
Stereographic (in all versions of PROJ and probably in GRASS'.
(I use precision in the sense of matching Roussilhe and not in
terms of Snyder's method).

I did find a site that looks Interesting:

http://www.atomnet.pl/~geodeta/2000/59text1.htm

BUT I can't read Polish.

Incidentally, some tables in above list k_0 factors.

On Mar 9, 2004, at 5:36 PM, <werchowyna at pf.pl> wrote:

> Hello everyone! This my first post to this list. My name is Maciek.
>
> I'm using Grass 5.03.
>
> I need to make a mapset in a projection called Roussilhe Oblique
> Stereographic (alias
> Quasi-Stereographic).
>
> The system name is "Uklad 1965" (eng. "System 1965"). It's an old, the 
> most
> popular and widely used system in Poland. The ellipsoid is Krassovsky, 
> datum
> Pulkovo 1942 modified for Poland.
>
> Issue - there is no projection called like Roussilhe or 
> Quasi-Stereographic
> in Grass.
>
> At http://crs.ifag.de they suggest to use Stereographic. Is it right? 
> If so,
> then WHAT SHOULD I INPUT FOR "LATITUDE OF TRUE SCALE". No such info is
> provided in any literature regarding the "System 1965".
>
> Any suggestions welcome!
>
> Maciek Sieczka
>
>
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