[Tilecache] TileCache with Google Maps ?

[Christopher Schmidt]

On Mon, Apr 28, 2008 at 05:23:36PM -0600, Gregor Mosheh wrote:
> >>Am I wrong, that the tileUrlTemplate method you're using could only work 
> >>if the cache were already seeded and accessible to the web?
> >Yes, you are wrong. This works through the TileCache TMS frontend, which
> >has nothing to do with the backend diskcache.
> 
> Hm; so the /1.0.0/layername/ part of the URL signifies a TMS request? 
> Pardon me if I'm a bit lost; I'm used to OpenLayers and TileCache, and 
> Google Maps and WMS, but not Google Maps and TileCache-TMS.

Yes. 

> 
> >>I also note that Google Maps' WMS requests use EPSG:54004 and not 
> >>EPSG:900913  I'm fine with listing them both in wms_srs but perhaps you 
> >>could clarify which one is used for what occassions?
> > * Google doesn't use WMS at all internally.
> > * The TileCache example I posted in that entry doesn't use EPSG:54004
> >   for anything.
> 
> Right. The WMS-for-GoogleMaps stuff I've seen all uses EPSG:54004 and 
> not EPSG:900913, and I have the access logs to prove it. Hopefully once 
> I get your example working, some of this will make more sense.

Note that these are different. When you're basing your tile origin based
on where you are in the map, it doesn't matter: over a couple thousand
pixels, it's no big deal. But when you're looking at a tile grid over
the *entire planet*, the minor differences between the two projections
end up with a significant difference.  

Regards,
-- 
Christopher Schmidt
MetaCarta