Thread: [Announce] modRana: a flexible GPS navigation system
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kureyon is offline kureyon
2011-08-25 , 09:49
Posts: 992 | Thanked: 738 times | Joined on Jun 2010 @ Low Earth Orbit
#861
Originally Posted by 白い熊 View Post
Google monitors I guess how fast subsequent requests for tiles come in and if it deems they're machine generated, then fails to serve the tiles.
I suspect they use some sophisticated heuristics to detect batch downloads. If it were simply based on speed of requests then I would expect at least the first few tiles to download correctly before the "speed limit" kicks in. All my attempts to batch download google tiles have failed (not 1 single tile downloaded). I zoomed out quite a bit then did a download 1km around view with zero levels up/down. This results in only 9 tiles to be downloaded, but all failed.

What might help, if you REALLY want to download google stuff, instead of just boycotting it,
I've no intention of boycotting them since google's map source (Mapabc) for China is by far the best of those available in modRana. In fact the other "commercial" providers Virtual Earth Map and Yahoo Map provide practically no coverage for China and OSM although a lot better than those two is still far from "complete".

would be to set the download threads to max out at 1 if possible (or is the lowest number 5?, don't remember), that might help it...
The lowest setting is 5 and still total failure

I'm wondering whether there are any differences in the modRana code to download tiles when scrolling around map and when doing the batch download.

Google Map Saver (GMS) seems to have a workaround for downloading a bunch of tiles at once:

Q: I think your tool breaks the Google’s Terms of Use
A: I was thinking about this before I made the application public. What I can tell you, is that I’m not using any tricks (e.g. direct and bulk downloads) to get the maps. I’m simply using the a standard Google URL via IFRAME. Google allows us to see bigger maps. I found is possible, I did it. In GMS one user request = one Google Maps access. No bulk download.
But that workaround involves the opening of a browser window and most likely uses google's javascript thingies to do the heavy lifting then GMS probably trawls through the browser cache to stitch together the tiles.