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I am using RMaps Ext (a rmaps mod) on Android, browsing offline maps created using Mobile Atlas Creator (MOBAC). It's working great so far.

The only problem is that when browsing offline satellite maps the zoom level is fixed to the tile layers I chose to download on MOBAC.

But I was wondering since I have already downloaded more detail satellite maps, e.g. zoom level 16, in theory I could browse zoom level 15, 14 to level 10. You just need some fast algorithm to zoom out a big image.

e.g.

  • The level 16 zoom file size is 80MB
  • The level 10-16 zoom file size is 120MB

So could the zoom out scaling be done on Android using the 80MB file directly?

It will save a lot of storage space (but spend more on CPU with image resizing)

Thanks in advance!

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The expected behaviour has to be provided by the application rather than not from Android services.

I have not used RMaps, but I use TrekBuddy which also uses offline map tiles created by MOBAC. The working nature of the MOBAC and hence these apps which depends on MOBAC does provide offline map tile in layers. Either Zoom level can be stored in a layer or different map types like satellite image, terrain, normal map etc can be in stored in each layer.

When I create offline maps I create them in various zoom levels say (from 15 to 10) each in seperate layer as shown: enter image description here

The apps like RMaps and Trekbuddy shows only one layer at a time. To simulate zooming, one has to load the layer with higher zoom level. Say for example, if I am presently viewing a map in zoom level 10, in order to zoom, I should load layer for zoom level 11 or higher. To ease this operation, Trekbuddy has a feature called easy zoom, with which (once configured properly), once can zoom with volume rocker keys. Pressing volume up will zoom up and pressing volume down will zoom down. However as expected this feature intervened with actual volume up and down feature and hence it was reported to work in few phones only (not working in mine - a LG Optimus One running Andorid 2.3.3/CM10).

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  • yes thanks but my main objective is to without the 10-14 levels, create 10-14 levels on-the-fly on android with the level 15 tiles. Is it possible?
    – est
    Commented Oct 15, 2012 at 6:55
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    That seems to be simply too much and not possible in my opinion. MOBAC creates only raster maps and not vector maps, which alone can be zoomed as you want. If that's the case you may have to opt for OSMAnd or NavFree which relies on Open Source Map with vector support.
    – Narayanan
    Commented Oct 15, 2012 at 6:59
  • Thanks again, but I am dl satellite maps for offline use, which IMHO is just a huge sized image.
    – est
    Commented Oct 15, 2012 at 7:59
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Yes, there's no reason you couldn't do this on Android. But you'd have to modify the app to generate the scaled tiles on-the-fly: it would certainly be fast enough on a recent phone with a good GPU. I don't believe there's already an app that does this: satellite maps are so large that wanting to use them offline is an unusual use case.

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