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I'm trying to create a moving map application for an embedded ATOM device. Data source is a 400MB tif file (500dpi) plus projection and worldfile. My naive approach was to load that tiff into Global Mapper and export it to "Bing", using 4 zoomlevels. It works fine, but the tilecache uses up way too much diskspace.

Can anyone point me to a better way of achieveing something like this? Would it be better to use some kind of runtime decompression?

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"moving" map? Do you mean "mobile" map application? –  underdark Oct 20 '10 at 18:27
    
I think he probably means webmap or slippy map. –  jvangeld Oct 28 '10 at 0:55

1 Answer 1

Try and reduce the original tiff to 254dpi >if possible run the exported files through export from Global Mapper via photoshop (fireworks even better) just created and run a batch import/export web optimised .png (don't make a copy, replace the original files)

The file size reduction is impressive and therefore speed up your map and tilecache on the browser.

GIMP can be used instead of Photoshop.

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There are also handy tools for further compressing pngs that can do better than Photoshop or GIMP. (codinghorror.com/blog/2007/03/getting-the-most-out-of-png.html) Additionally, if your map is imagery-based, consider using .jpg instead, which will compress it much better due to being lossy. (png is better if you need perfectly sharp images and text!) –  Dan S. Sep 20 '10 at 16:39
    
I didn't say it was the best method, thanks for the additional links. IF you need transparency JPG is out. small and simple images may actually compress better using PNG than JPG. It seems to depend on how much is "going on" in the image. PNG works best for vector type graphics (maps!) with hard lines. JPG works best for anything with complex gradients –  Mapperz Sep 20 '10 at 19:22

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