We generate raster map tiles and deploy them in the server, then we use javascript in the client to request the tiles and re-organize them to map.(like google map and Openstreetmap).

However this is the PC solution. And the tile size is 256x256(pixel) with 96dpi.

Now we want to build apps in android and iOS.

However we found that the same 256x256(pixel) tile will have a different visual effect in devices with different resolution and the tile is almost unreadable in a high-resolution device(The text and labels in the tile is too small).

Then I wonder how do you make the tiles readable in the mobile device, is there any way to improve them?

  • Have you actually tried this? What did you see? As far as I can tell, OpenStreetMap and Google maps from the web look fine on my Android device. BTW: Are you sure that your caching on the server is a legal use of Google Maps data?
    – BradHards
    Dec 26, 2013 at 0:49
  • I just take google map and openstreetmap as an example, in fact, we generate our own tiles.
    – giser
    Dec 26, 2013 at 0:59

3 Answers 3


I think the only way is to rerender the map for a bigger ppi device, and serve that on mobile devices. Rerender would include bigger labels, larger symbols, etc.

  • Hi, we tried to generate tiles of different dpi for different, but this is a big job since there are so many android devices, any way to make this easy?
    – giser
    Mar 28, 2014 at 2:29
  • Yes, there are many devices with different display resolutions, but generally their PPI is around 330 (modern high end smartphone) or around 200 (middle and low end devices). So that would leave you with 2 different renders of maps. But i would go with one compromise version, say such, that fits well with 250DPI or something like that.
    – U2ros
    Apr 2, 2014 at 11:43

Openlayers allows you to change the DPI setting using something like:

OpenLayers.DOTS_PER_INCH = 96;

Of course, you'll still need to increase the DPI on your tile-server; no idea how to do that as we don't know what you're using.

The "correct" answer however is likely a non-technical one.

You need to design your tiles for the target audience as you would with any map. Read the Ordnance Survey's Cartographic design principles - You'll see there's a section for Consideration of display format. What you need to do is redesign your tiles so they're better suited for the mobile displays you're targeting. I suspect that one carefully designed style would work for both PC and mobile.


I've had good luck with pulling mbtiles from MapBox onto Android devices. Perhaps you might want to serve tiles with TileStream.

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