[OSM-dev] South Pole at 0,0 ?

[Matthias Julius]

Martin Koppenhoefer <dieterdreist at gmail.com> writes:

> 2010/1/26 Matthias Julius <lists at julius-net.net>:
>> I have the suspicion that osm2pgsql (which is doing the conversation
>> to Mercator, right?) somehow falls back to 0,0 when it can not deal
>> with an indefinite northing value.
>
> I also came across this issue, but AFAIK mercator is not suitable for
> north- and southpole: it is not defined in these regions (don't
> remember exactly but it was like bigger/smaller than 85 Deg.
> North/South). For further reading look for Mercator-projection in the
> Web.

Of course, Mercator is not suitable for for the polar regions.  The
poles are in the infinite.  That's why I would expect Mapnik not to
put the South Pole on a Mercator map.  And now look at our Mapnik
layer:
http://www.openstreetmap.org/?lat=0&lon=0&zoom=18&layers=B000FTF

Mercator is defined right up to the poles - the scale just grows
larger and larger and at the poles it is infinite.  Our limit of about
85° comes from us wanting a square map.

Matthias