[Xastir] Script to cache some maps

[David Ranch]

Hello Jason,


> You missed the initial post and you have fallen for the "everyone is always
> online", "bandwidth is plentiful", and "bandwidth is free" fallacies.

Ha.. no, I do understand the goal here and I too don't want to have to 
be 100% online with a *very* fast Internet connection to provide snappy 
response times.


> A full set of tiles (that's global coverage and global zoom levels) is not
> practical to store (many TB or PB) - that's why the tile servers
> (OpenStreetMap, etc) don't do it that way, and instead choose to generate
> the requested tiles on the fly.

Ok.. so this is was part of the detail that I'm not familiar with and 
why I asked what that 11GB of data really consists of.  I agree it's not 
practical to store, maintain, and update TBs of data but is that what 
we're really looking at here?  For me, I would think I'd like to have:

    - All zoom levels for the Silicon Valley area in California
    - Most zoom levels for the greater bay area
    - A good overview (a few zoom levels) for all of California

Starting with this example, can you provide an estimate of how much 
storage that might be?   If that's really 10s to 100s of GB, yes, that's 
not going to work but if the next solution would be to create a local 
tile server to my Raspberry Pi2 (just an example) to dynamically render 
tiles for areas I want from a similar geo area of SHAPEFILES, I doubt 
things would remain "snappy" on the UI side of things.

Maybe this all just can't be easily had (have my cake and eat it too)?   
I'm still learning here so please be gentle!

--David
KI6ZHD