> captionless is only z12 We discussed this recently and came to the conclusion that the captionless layer should exist for more levels than just z12, so that we could do things like support labels in other languages. See:
http://lists.openstreetmap.org/pipermail/tilesathome/2008-June/002315.html > But then I plan to not store empty z12 tilesets at > all, but have a "blank tileset db" for that (which only has entries for > completely empty tilesets). But given that we currently waste tons of > diskspace for the millions and millions of files and thousands of > directories (which all use up an unknown minimum filesize), I would think > that we waste still much less space than we currently do. The blank tile database will be the biggest savings in space of anything we can do, particulary if it is fully recursive. There are 16 million tiles at z12, and 13 million of those are sea. If we support recursive blankness (such as one z3 blank entry instead of 262144 z12s), all of the blank sea can be stored in a few hundred thousand tile entries. Here is a recursive breakdown of the oceantiles data: Count Zoom Type 21 3 sea 4 4 land 29 4 sea 44 5 land 137 5 sea 157 6 land 353 6 sea 510 7 land 923 7 sea 1503 8 land 2225 8 sea 4547 9 land 5200 9 sea 13332 10 land 12142 10 sea 34945 11 land 27812 11 sea 86587 12 land 64455 12 sea Nearly all of the sea will be blank. Much of the land won't be blank, but with our Mercator projection, there are a lot of blank land tiles in the North. If we can't do full recursion, then hopefully we can at least do z6 to eliminate 4096 blank z12s. In addition to the ocean, there is quite a bit of Yukon, Greenland, and Siberia that can be stored in blank z6 entries. - Alan _______________________________________________ Tilesathome mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/tilesathome
