[OSRS-PROJ] Polar Stereographic Projection

[Ray Bryan E 2Lt 314 OSS/OSW]

I have a quick question I hope to get some advise on.


I am trying to retrace the outline of the US that is on a weather satellite
image.  The image is in the form of a polar stereographic projection (so
I've been told).

I have created a routine that reads map coastal data for the US (lat/lon
values) and run the values through proj.4 and get output x,y coordinates.  I
have successfully drawn a map of the US, but the drawn map doesn't match the
image map close enough.  It seems that the northern portion of the map
(Maine to Washington state) needs to be narrower, and the southern portion
needs to be wider.  This discrepancy is only by a few longitude degrees, but
still not as close as I would like.

Ok, here are my questions...

1.  Could the problem be in the wrong ellps that I use?  (I have tried
several, with not much change)?

2.  Is there any way I can adjust the input values to modify the map the way
I want it?

I am very new to cartography type stuff, and still in the learning process,
so any suggestions will be greatly appreciated.

This is what I'm using for input values to get the US map.

 +proj=stere +lat_ts=90 +lat_0=110 +lon_0=100d40E 
        +k=1 +ellps=sphere

Another point, the +lat_0=110 seems to be very odd, but this is the value
that I had to input to get the map to somewhat line up.


Thank you

Bryan Ray

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