What is the effective and legal way to get map tiles for the size of 2 or 3 states?

Question

I would like to get map tiles possibly from Open Street Map (yes I am aware about tile usage policy and would not like to breach that) or other source for the purpose to serve it as offline maps to applications.

Total area will be of the size of let’s say 2 or 3 states of US (300K square miles) and from zoom level 1 to 12 levels (possibly in future up to 17 levels), so I think it will be couple of GBs.

Possibly it can be 2 ways, generating those map tiles locally by OSM data or download tiles from some source with some utility. Or may be I have no idea and there is something simple exist!

What are the specific ways this can be achived quicker, easier and legal way?

Answer 1

I'd recommend using TileMill to generate the tiles, it can save them out to a variety of formats including as mbtiles bundles which can be used for offline applications. Tilemill will give you cartographic control over the maps, and produces beautiful results.

Alternatively, you could download the styled data from Cloudmade, the .img files should be full resolution and you can use your tileserver or GDAL to produce the downsampled tiles. You'd still need a distribution format however, which is something TileMill handles for you which is nice.

Answer 2

Another way would be to use Maperitive's generate-tiles command.

Note: "couple of GBs" could be an optimistic estimate. Also note that Web tile servers usually don't pre-render all high-zoom tiles (like those for level 17) because a very small number (less than 1%) of them is actually ever used (requested) by browsers. So you'd probably need a way to generate tiles on demand.