[Proj] Re: Oblique Parameter Question (Mike Darweesh)

Melita Kennedy mkennedy2 at earthlink.net
Tue Nov 1 22:29:56 EST 2005

Mike and Michael,

I don't know if this will help at all. o_lon_p and o_lat_p define the new pole 
for the latitude and longitude values. So the lat/lon values are converted  
to a new, rotated sphere, then projected. I assume the values you set 
for the projection should be based on the new spheroid. John Snyder 
talks about this theoretically in _Map Projections: A Working Manual_, pp 29-32. 
ASU libraries reports that there's a copy in "Hayden US Documents", I 19.16:1395.

Melita Kennedy
ESRI Product Specialist


Date: Fri, 28 Oct 2005 18:30:32 -0700
From: Mike Darweesh <mjd at surly.org>
Subject: [Proj] Oblique Parameter Question
To: proj at lists.maptools.org
Cc: Michael Weiss-Malik <gigabyte at east.mars.asu.edu>

Hi All,

Michael and I are trying to learn about the ob_tran projection in order to
facilitate use here at the Mars Space Flight Facility. We need more
information about the o_lon_p and o_lat_p parameters. Could someone give an
exact English description of how they operate or a URL to such. We
understand the notion of an oblique projection, but we're having a hard time
understanding how these parameters define the "obliqueness". We applying
these to eqc (Platte Caree) if that simplifies your answer at all.

-Mike and Michael

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