# [Proj] Re: Newbie Polar stereographic question

starjohn starjohn at hotmail.com
Wed Jul 12 14:22:36 EDT 2006

```Hello Gerald!

Thanks a lot for the reply!

As far as I know, the projection plane is on latitude 60 and parallel to the
equator (this is the meaning of true latitude).

There is a ray from the center of earth to this plane. The center of the
projection
is the point on this plane where the ray from the center of earth goes
through the center
point and "meets" the plane.. this is the center of the projection. Makes a
sense ?

There is a drawing on mathworld to see this in better detail on
http://mathworld.wolfram.com/StereographicProjection.html

Thanks again and all the best
John

> On Tuesday 11 July 2006 2:29 pm, starjohn wrote:
>> Hello!
>>
>> I got image from a korean customer which is polar stereographic with
>> center
>> Longitude=127, and center latitude = 35
>> The true latitude is 60. How do I use polar stereographic in this case ?
>> Is
>> it possible to specify true lat other than
>> 90 or -90 ?
>
> "Polar" Stereographic may be a bit of a misnomer.  I suspect simple
> Steregraphic is  what is meant with the point of tangency at 127E? and
> 35N?.
> In proj4 terms: +lat_0=127E +lat_0=35N.
>
> I cannot imagine anyone using truly polar stereographic at a latitude of
> 35
> degrees.
>
> --
> Jerry and the low-riders: Daisy Mae and Joshua
> "Cogito cogito ergo cogito sum"
>   Ambrose Bierce, The Devil's Dictionary
>
```