[OSM-talk] Projections

[Christopher Schmidt]

On Fri, Jan 19, 2007 at 03:37:19PM +0000, SteveC wrote:
> * @ 19/01/07 03:30:15 PM andrew.rowbottom at gmail.com wrote:
> > >Are you trying to say that there is a standard for tiling in Mercator
> > >projection written down somewhere, and we are breaking it?
> > 
> > The big issue here is that the program used to display the tiles must
> > know the projection used if it wants to convert pixel coordinates (or
> > tile names) to lat/long. The current implementation assumes a
> > particular conversion that is not the same for all the different sets
> > of tiles.
> 
> The current (top two layers) tiles can be dropped in to google maps -
> it's a pretty compelling reason to stick with it.

Unless you're using a different definition than I am, I don't think
that's true... maybe I'm misunderstanding something though. Google, in
my experience, uses a simple mercator projection, and OSM isn't creating
tiles that match that...

Regards,
-- 
Christopher Schmidt
MetaCarta