On Sun, 2011-01-16 at 03:25 +0100, Frederik Ramm wrote: > Maybe we should start some sort of general metatile utility, or > collection of utilities. Tirex already has at least one such thing, a > metatile viewer, that has nothing to do with Tirex itself - it is > useful > for everyone working with metatiles, as would your tool. > > The way I see it, the concept of metatiles is a general concept used > by > (currently) at least three different components - mod_tile, renderd, > and > Tirex. Ideally of course there would be a library that does all the > metatile stuff (computing paths and so on) used by everyone, but > that's > maybe too hard because it would have to be usable from so many > different > places. > > I would be interested to hear Jon's opinion about this. >
Splitting the meta tile handling code out into a library could be useful. We already have implementations in C, Perl and Python so we ought be able to extract a set of typical APIs: - x/y/z to filename - filename to x/y/z - reading a specific tile, or all meta tiles at x/y/z - writing a tile specific tile, or all meta tiles at x/y/z - metadata about a tile: timestamp, x & y bounding box - is x/y/z a valid tile co-ordinate The code for the above is fairly standard and should be applicable for any application wanting to use mata tiles. I would be less certain of including the next layer of code which would likely come above this: - lat/lon to tile (and reverse) - lat/lon bounding box to list of tiles - scanning the filesystem and returning what tiles are found I think it should initially be limited to the current OSM/900913 tile layout but perhaps in the longer term it could also implement a different tile layout for EPSG:4326. Other possible enhancements: - Configurable tile size: 64 pixel etc - Embed the mime-type in the meta tile, allowing JPG tiles etc - Support a different directory layout supporting higher zoom levels Jon _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
