[OSM-talk] Tile data server

OJ W ojwlists at googlemail.com
Sat May 31 21:16:12 BST 2008

Hi.  I've been looking at the tile data server idea[1]. It's like a
cacheable way of getting OSM data, without having to spend the whole
day downloading and processing planet.osm or similar.

It only has the most basic implementation running [2] so far, but
might be enough for some research projects to use.

- UK only
- query at zoom-15 only
- 2008-05-21 data only
- no way-simplifying as you request lower zoom levels

so you can request a z15 map tile, and get back OSM data, but with
useful stuff added

- ways containing all their tags, as normal
- position of each node is within the way itself, so you don't need to
do topological -> topographical conversion or store a huge list of
node positions
- still contains node IDs, so you can locate connections (unlike
postGIS linestrings)
- positions already projected into slippy-map tile coordinates [3], to
make tile-rendering faster

obviously the big push for this type of server is to do on-demand
rendering (where you don't need to specify new map layers a year in
advance, or need one server per map layer) e.g. see pyrender idea

but another use might be the routing, where you just keep loading new
tiles as your route moves between areas, rather than needing to load
everything at the beginning.

I'd appreciate some help writing/running servers for this type of API,
if anyone thinks it might be generally useful.

[1] http://wiki.openstreetmap.org/index.php/Tile_data_server

[2] http://wiki.openstreetmap.org/index.php/OJW%27s_tile_data_server

[3] http://wiki.openstreetmap.org/index.php/Slippy_map_tilenames

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