# [Proj] Rotated Polar Stereographic Projection in Proj4

Alexander Jarosch ajarosch at eos.ubc.ca
Thu Mar 5 16:58:39 EST 2009

```Gerald I. Evenden wrote:
> On Thursday 05 March 2009 2:40:53 pm Alexander Jarosch wrote:
>
>> Hello!
>>
>> I have a rather simple question, but I could not find any documentation
>> so far on how to do this with proj4. A college of mine has maps on a
>> "polar stereographic projection" with the following details:
>>
>> Pole_lat = 50.0
>> Pole_lon = -150.0
>> Central_lat = 50.0
>> Central _lon = -126.0
>>
>> These are the definitions he gave me. Now I think this is a
>> stereographic projection with a given pole lat/lon and should maybe not
>> be called polar stereographic, but that is not the problem. I want to
>> set up proj4 (or cs2cs for that matter) to this projection to transform
>> coordinates from lat/lon and I assume the same ellipsoid. My problem is
>> that I did not find any documentation on how to set up this rotated
>> stereographic projection with proj4.
>>
>> Any help would be really appreciated.
>>
>
> Appears to be a truely oblique projection and not in the tradition of
> proj=stere where the pole is on the CM.
>
> Is a spherical earth used?  In the case of a spherical earth one could use the
> combination of proj=ob_tran and stere.  Otherwise, if it is a azimuthal
> stereographic, I do not know of anyway proj or libproj could handle it
> without development.
>
> Sheeesh.  I wonder what the rational for this beast was?  Class exercise?
>
>
Nope that beast comes from a climate model ;-). Anyway, is it fairly
simple to work out the combination of +proj=ob_tran and stere for this
projection I mentioned, because it assumes a spherical earth, like
almost all climate models.

Thanks.
Alex

--
Alexander H. Jarosch
Post-Doctoral Fellow
Department of Earth and Ocean Sciences,
The University of British Columbia,