[OSRS-PROJ] Oblique Stereographic

[Frank Warmerdam]

Folks,

I understand that there are (at least) two common forms of the Oblique
Stereographic projection.  In the Mentor Software system they are referred
to as the "International" version and the "Snyder" version.  It appears that
the "proj=stere" used like this "+proj=stere +lat_0=34.2 +lon_0=39.15
+k=0.999534 +x_0=0 +y_0=0 +a=6378249.2 +b=6356515 +units=m" implements the
Snyder version.   I am wondering if there is a version of the "international"
equations in PROJ.4 already?

The differences are on the order for 1 arcsecond for my test case ... pretty
substantial.

PS. I believe I am assuming that coordinate systems such as "Deir ez Zor /
Levant Stereographic" listed in the EPSG database with method code 9809 are
the so the called International version.  The EPSG database gives the
equations for it's method, and notes that Snyder discussed a different
formulation that produces different results.

PPS. Anyone interested in implementing the EPSG equations if they haven't
already been incorporated into PROJ.4 under another name?

Best regards,

-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent


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