[OSM-talk] Mapnik+OSM and TileCache

[Christopher Schmidt]

After a heck of a lot of hacking last night, I finally got OSM rendering
via mapnik. After some more playing, I added a mapnik layer to
TileCache[1].

The upshot?

http://labs.metacarta.com/wms-c/demo.html?lat=51.51777&lon=-0.10979&zoom=9&layers=00B00000F

Just-in-time (cache as you drag) OSM, based on the 11-20-06 planet.

Questions that I have been asked:
 * Can it do mercator? Yes, absolutely. It only doesn't because the
   existing caches for the other 7 layers are not Mercator.
 * Is it WMS? TileCache can take requests in either TMS or WMS formats,
   but it simply parses these requests down to the appropriate TileID. 
 * Does it have any additional dependancies? Nope. Once you have Mapnik
   installed, the only additional dependancy is TileCache, which is
   pure-python BSD licensed code.
 * How are the tiles stored on disk? Because of the limitations of the
   ext3 filesystem, tiles are split up into multiple subdirectories, but
   these directories are regular, and very similar to the 'GoogleLike'
   file structure:
     ./14/000/016/352/000/012/853.png
       (zoom) (x0, x1, x2) (y0, y1, y2)  
   It's also possible (simple) to write your own file caching plugin,
   that (for example) stores tiles on multiple servers, or use the
   memcached memory caching plugin for faster access and distributed
   caching.  

The Mapnik layer should be in the next release of TileCache, sometime in
the next two weeks.

[1] http://labs.metacarta.com/wms-c/

Regards,
-- 
Christopher Schmidt
MetaCarta