[OSRS-PROJ] Oblique Stereographic

[Administrator]

Hey Frank,

If you have the equations for this projhection, I'm willing to give it a
go.

John Novak
Novacell Technologies
www.novacell.com

-----Original Message-----
From: Frank Warmerdam [mailto:warmerdam at pobox.com] 
Sent: Friday, February 14, 2003 12:01 AM
To: PROJ.4 Discussion
Subject: [OSRS-PROJ] Oblique Stereographic 


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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