Loading ...
Sorry, an error occurred while loading the content.

prefetching tiles

Expand Messages
  • kc9gqr
    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?
    Message 1 of 3 , Feb 28 1:53 PM
    • 0 Attachment
      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?
    • Lynn W. Deffenbaugh
      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
      Message 2 of 3 , Feb 28 4:20 PM
      • 0 Attachment
        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?
        
        
        
        ------------------------------------
        
        Yahoo! Groups Links
        
        <*> To visit your group on the web, go to:
            http://groups.yahoo.com/group/aprsisce/
        
        <*> Your email settings:
            Individual Email | Traditional
        
        <*> To change settings online go to:
            http://groups.yahoo.com/group/aprsisce/join
            (Yahoo! ID required)
        
        <*> To change settings via email:
            aprsisce-digest@yahoogroups.com 
            aprsisce-fullfeatured@yahoogroups.com
        
        <*> To unsubscribe from this group, send an email to:
            aprsisce-unsubscribe@yahoogroups.com
        
        <*> Your use of Yahoo! Groups is subject to:
            http://docs.yahoo.com/info/terms/
        
        
          

      • 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 3 of 3 , Feb 28 10:01 PM
        • 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?
          
          
          
          ------------------------------------
          
          Yahoo! Groups Links
          
          <*> To visit your group on the web, go to:
              http://groups.yahoo.com/group/aprsisce/
          
          <*> Your email settings:
              Individual Email | Traditional
          
          <*> To change settings online go to:
              http://groups.yahoo.com/group/aprsisce/join
              (Yahoo! ID required)
          
          <*> To change settings via email:
              aprsisce-digest@yahoogroups.com 
              aprsisce-fullfeatured@yahoogroups.com
          
          <*> To unsubscribe from this group, send an email to:
              aprsisce-unsubscribe@yahoogroups.com
          
          <*> Your use of Yahoo! Groups is subject to:
              http://docs.yahoo.com/info/terms/
          
          
            

        Your message has been successfully submitted and would be delivered to recipients shortly.