[OSM-talk] db and user statistics update

[Christopher Schmidt]

On Thu, Jan 18, 2007 at 11:13:18PM +0000, Robert (Jamie) Munro wrote:
> > * it should be complete, i.e. all tiles should be there (99% of the world
> >   does not have OSM data, so that shouldn't be too hard to do with just
> >   the continents and country borders.)
> 
> Although Mapnik WMS-C is in many senses the best layer (it generates in
> real time - so always has data), we can't use it because it uses a
> complicated strict spheroid version of the Mercator projection, rather
> than the simple sphere-based one that everything else uses. While it
> makes a difference of a few km in the UK, I see very little advantage to
> the projection in practical terms, and the maths is much harder. I think
> that either it should be changed to match the other projections, or it
> should be removed. I know the author of the WMS-C layer will probably
> say Christopher Schmidt will say "But my projection is right and yours
> is wrong", but in fact they are both wrong. In reality the earth is
> round and doesn't fit on a 2d screen. Neither projection is "right", nor
> is any other.

The WMS-C matches Google, which is the only 'right' aspect it has.
Neither it nor the map which is based on a spheroid is 'right', you're
absoltely correct.

However, matching other maps which are projected in simple mercator is
an important use case for what I use the map for, so I won't be changing
it.

I advise removing the WMS-C layer from the OSM homepage: it's confusing
and useless in that interface.

Regards,
-- 
Christopher Schmidt
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