[OpenLayers-Users] confused about spherical mercator

[Christopher Schmidt]

On Wed, Apr 16, 2008 at 06:28:57PM +0200, G. Allegri wrote:
> Hi everyone.
> I'm a bit confused about spherical mercator property...
> 
> In the relative example from dev/examples, the SM is set for all the
> layers, except the OSM ones. Why? I thought that both OSM and Google
> use the Spherical Mercator. I think I've misunderstood it's effect,
> when both Projection and DisplayProjection options are also set in the
> map options...
> In other words: what is reprojected relatively to what?

sphericalMercator is a way of saying "This API works, natively, in
lat/lon, but uses raster images based in spherical mercator." It only
makes sense when using a commercial/third party API for which this is
true: all the 'native tile access' mechanisms don't need this flag.

OpenStreetMap data is accessed directly as tiles, so we don't need to
use the flag for it.

The configuration that matters for OSM is the map configuration options,
defined as var options = {} above. 

Regards,
-- 
Christopher Schmidt
MetaCarta