Polar Stereographic

[Tyler Mitchell]

Dominic,
Did you get this working?  I have an app that shows some lat long data
projected to stere.

Tyler

On February 18, 2005 07:47 am, Dominic Lowe wrote:
> Hi All,
>
> This query is probably more to do with map projections than with
> Mapserver, depending on where I'm going wrong...
>
> I'm trying to display Polar Stereographic maps (of Europe) in Mapserver.
> I can successfully display the maps, but something is not right as they
> don't reproject properly to other coordinate systems (eg epsg:4326) - by
> this I mean they reproject but the map will appear distorted in the
> wrong part of the lat lon world.
>
> So anyway I think that I've just created an arbitary projection and got
> them to display somehow. What I'd like to do is display them in an epsg
> compliant Polar Stereographic...
>
> I've added a line to the epsg file:
> <9810> +proj=stere +lat_ts=90 +lat_0=90 +lon_0=0 +k_0=1.0 +x_0=0 +y_0=0
>
> this is based on the information here:
> http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html
> North Pole (NatOriginLat > 0): *
>
>   +proj=stere +lat_ts=/Latitude at natural origin/
>               +lat_0=90
>               +lon_0=/Longitude at natural origin/
>               +k_0=/Scale factor at natural origin/ (normally 1.0)
>               +x_0=/False Easting/
>               +y_0=/False Northing/
>
> *So I think by setting lat_ts to 90 I've assumed that the "projected
> image" is tangential to the north pole.
>
> So then I've tried different methods for converting the lat lon
> coordinates into Eastings Northings to be used in a world file to
> accompany the image. If the 9810 definition is ok then I think this is
> where I'm going wrong - there seem to be several possible coordinate
> systems that lay claim to the name 'Polar stereographic' - (eg UPS - is
> that the same as vanilla Polar?) and I'm not sure which one relates to
> epsg:9810 that I 'think' I've defined.
>
> Anyway, I'd very much appreciated it if anyone has any experience of
> using Polar Stereographic in Mapserver and could help clarify these issues.
>
> Regards
>
> Dominic