On Jan 5, 2008 7:06 PM, Sebastian Spaeth <[EMAIL PROTECTED]> wrote: > > - When the server has the list of blank tiles to insert, it could run > > one pass over the list to see if it's mostly sea of mostly land and > > whatever it is, insert a blank tile with that type at zoom-12 and then > > only insert the other types. > > Yes it could do that. My idea was to not take that hit at each insert, > but rather run a cleanup script periodically that does these kinds of > optimizations with lower priority. Once a z12 tile is marked as blank > land/sea by such a script subsequent blankness entries at higher zoom > levels become noop's.
Sure, but it also cuts the number of insert to be done in the first place, which produces a measurable speed improvement. > Yes, the script only performs some optimizations, namely removing all > redundant entries (that is those which have the same blankness > information at a lower zoom level). I planned to add -but never got to > it- a "bubbling up" of blankness information which would remove many > entries. I actually have a script which grabs all the data for a given set of zoom levels and actually calculates the minimum number of blank-tile entries needed to represent that. It produces rather spectacular results (>90% removal of entries). It's just complex enough that I've left it for a few days so I when I look at it again I can recheck the assumptions, but I'm pretty sure it works. The way it's setup is a sort of daemon that monitors for newly uploaded tilesets and optimises them straight away. It's quite quick so eventually I'll probably run it over the entire DB and see how it goes. If you're interested I can check it into SVN, maybe you can check it for bugs... Have a nice day, -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ _______________________________________________ Tilesathome mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/tilesathome
