OfflineCacher – new version (v.4)

A new version of OfflineCacher has been published. The instructions are still the same and are available from previous post. The same post has more information on what OfflineCacher can do. In short – it is an Windows Mobile Smartphone application to enable geocaching from your mobile phone without ever using the GPRS (data) connection – this is really useful when traveling as roaming charges most of the time are through the roof.

New functionality:

  • Map storing is optimized to reduce space occupied up to 4x. It is done in two steps – first the application no longer converts every tile to PNG format (for satelite images this enlarged the files by up to 10x). The second optimization is merging these small images into larger “archives”. This optimization also dramatically reduces time needed to copy the maps to storage card.
    • Previously (map for 5 caches): 947 files and 33,8 Mb.
    • Now (map for the same 5 caches): 8 files and 12,64 Mb.
  • When viewing the map if a tile is not available the application now looks for a image from level higher and resizes that (useful when driving around where the maps are not downloaded).

Note that this change makes all previously downloaded maps unusable. You should delete them (folders OpenStreetMap, GoogleStreetMap and GoogleSatelite) manually to free up disk space.

One of the reasons why the maps now take up much less space is that with usual storage card file systems there is a thing called allocation unit – any file will occupy certain number of these units and they can never share one unit. The default unit size is 4Kb so if a file is 6Kb large it will occupy 2 units and the actual size used will be 8Kb. This overhead is too small to notice for large files but if every file is smaller than 10Kb then the overhead is 30% to 50%. By merging the map tiles together this overhead is reduced to minimum.

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