Hi Jonathan and Magi,
I agree with Jonathan about adding the latitude_of_projection_origin to the
polar stereographic projection. I have done that, and have added the
Lambert azimuthal equal area projection.
As this is the first time I've modified the CF document since the release
of version 1.0 I've also added a note at the top of the document about how
changes will be indicated, and a revision history section at the end. The
items in the revision history are linked to the actual changes in the
document text. Comments welcome.
Brian
On Tue, Jun 15, 2004 at 09:16:20AM +0100, Jonathan Gregory wrote:
> Dear Magi et al
>
> As far as I can tell, polar stereographic and general stereographic are the
> same operation, but perhaps the longitude doesn't play quite the same role.
> With a general stereographic projection, the longitude and latitude of the
> projection origin must be specified, and the meridian passing through the
> projection origin (along its longitude) is the central meridian of the
> projection, and appears as a vertical line in the middle of the map. For a
> polar stereographic projection, *all* meridians pass through the projection
> origin. The way to orientate the map is therefore arbitrary, so we specify
> one of the longitudes (the straight vertical longitude) to be the vertical
> line running upwards from the middle of the map.
>
> But in both cases the latitude_of_projection_origin is needed, so I think
> this ought to be added to the definition of polar_stereographic. It is
> allowed to be -90 or +90. This could be avoided by having separate projections
> of north_polar_stereographic and south_polar_stereographic but no-one does
> that apparently.
>
> I am not very well informed about map projections so if anyone else can
> correct or comment on the above that will be welcome.
>
> Cheers
>
> Jonathan
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Received on Tue Jun 15 2004 - 08:37:50 BST
