2009/5/31 Frederik Ramm <[email protected]>: > Hi, > > Tels wrote: >> Well, one could fetch the data at z17, see it is below some >> $ARBITRARY_THRESHOLD, zoom out to z16m, fetch again, and if still below >> $THRESHOLD, repeat it until either there is too much data (display >> message) or the user-requested zoomlevel was reached. > > I think the ti...@home folks already keep a database that says how > complex each level-12 tile is. So if we were not so busy telling them > how they're technologically backwards and how their whole project is > rubbish, they might just give us that.
Each t...@h user uploads a tileset at z12, which is indeed a pretty good indicator of the complexity of the area, see this heatmap rendering of the world at z12 from the t...@h data: http://u.nix.is/~avar/osm-heatmap-black.png I made if after requesting the z12 tileset sizes on the t...@h list: http://lists.openstreetmap.org/pipermail/tilesathome/2009-May/005859.html The code to generate it is under applications/rendering/tah-heatmap in SVN: http://trac.openstreetmap.org/browser/applications/rendering/tah-heatmap/README In particular the parse-filesize.pl script in that directory converts ls -R format provided by spaetz to an easy-to-use CSV format, e.g.: 0000,1042 158211 0000,1043 203915 0000,1055 172469 0000,1056 80728 t...@h currently has around a million z12 tiles, or ~5.6% of potential z12 tiles: $ wc -l tile-sizes.dat 937254 tile-sizes.dat It would be easy to make a web service which kept these tile sizes in a hash table and told e.g. Potlatch whether or not the z13 tile it's requesting is part of a z12 area that's say 10 times bigger than the median z12 tile. Which should cover the yellow/read areas on the above heatmap. _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
