[GIS] Optimizing OSM tiles download

cloudmadeopenstreetmaptiles

Disclaimer: I don't know anything about maps, please excuse me.

In our mobile app, we use Cloudmade as our map tiles provider.
For certain places, we download multiple tiles for each zoom level (level 13 through 19) to be used offline.

The thing is that sometimes you need to download tiles for thousands of places at once, making it a very lengthy download.

We are trying to optimize this process and there are a few things that I've come up with, which I don't know if they even make sense:

  1. Cloudmade serves the tiles as png files. We could try to cache those tiles in our server, and reduce their size.
  2. Skip some zoom levels, let's say we only download one every two (13,15,17,19).
  3. Download a higher quality version on a higher zoom level, let's say 10 and split it up in the client.

Do any of these sound reasonable? What else could we do?

Thanks a lot!

Best Answer

I've never used Cloudmade but generally caching will improve the performance greatly. Did a quick search and it looks like cloudmade prohibits caching of their tiles offline on your own servers unless you have the right API subscription key. Not sure if you have that, but if you don't looks like you will be in violation of their TOS.

http://support.cloudmade.com/mobile-fair-use

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