On Sun, Apr 27, 2008 at 1:34 PM, Tom Hughes <[EMAIL PROTECTED]> wrote: > > > x = (int) Math.floor((longitude + 180) * 65536 / 360); > > > y = (int) Math.floor((latitude + 90) * 65536 / 180);
> Yep - the input (after adjusting to zero) is between 0 and 360 (for > the longitude) or 0 and 180 (for the latitude) and we want to produce > a 16 bit integer so the result needs be between 0 and 65535 or we will > overflow sometimes. Interesting. so the area covered by the quadtiles at the edge of the map is half that of the rest of the tiles. Was this scheme chosen specifically or is it just the way it was done at the time. If s = 360/65535 then: quadtile 0,0 is [0,0.5s]left/right and [0,1s] up/down quadtile 1,1 is [0.5s,1.5s]left/right and [1s,3s] up/down Have a nice day, -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
