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RE: [aprsisce] prefetching tiles

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  • Robin Williams
    Phew???? That s a fair few tiles. Bet you the local telco s would love that on a mobile data connection.lol Robin ZL3REW _____ From: aprsisce@yahoogroups.com
    Message 1 of 3 , Feb 28, 2010
    • 0 Attachment
      Phew????
      That's a fair few tiles.
      Bet you the local telco's would love that on a mobile data connection.lol
       
      Robin ZL3REW


      From: aprsisce@yahoogroups.com [mailto:aprsisce@yahoogroups.com] On Behalf Of Lynn W. Deffenbaugh
      Sent: Monday, 1 March 2010 1:20 p.m.
      To: aprsisce@yahoogroups.com
      Subject: Re: [aprsisce] prefetching tiles

      See my response to N7FMH to see why this is not necessarily a good idea.  It has to do with what area coverage is desired for the increasing zoom levels, all of the area originally covered or just the center as if you had manually zoomed the whole way in at a constant screen center.  The client currently does the former on the prefetch which results in a 4x tile count for each zoom closer.  The latter does a constant tile count per level, but doesn't end up fetching detail for ALL of the area originally viewed.

      See the table at http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Zoom_levels to get an idea of the total tile count for various zooms.  For your suggestion of 15, if you did this while zoomed out to the planet view, you'd end up fetching (left column is zoom tile count, right column is cumulative total).

      11
      245
      31621
      46485
      5256341
      610241365
      740965461
      81638421845
      96553687381
      10262144349525
      1110485761398101
      1241943045592405
      131677721622369621
      146710886489478485
      15268435456357913941
      1610737418241431655765
      1742949672965726623061
      181717986918422906492245

      Oh, and you'd have to multiply all of those numbers by the number of tiles it takes to fill the screen from which you did the Prefetch.

      Lynn (D) - KJ4ERJ

      kc9gqr wrote:
      when prefetching tiles  is there a way to change how many zoom levels is prefetched?  i think its 5 but can you cange it to like 15 in the xml file?
      
      
      
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