Command-line Yaouh! clone

[Helge Hafting]

Risto H. Kurppa wrote:
> On Thu, Apr 23, 2009 at 4:11 PM, Helge Hafting <helge.hafting at hist.no> wrote:
>>> These here sound good to me to have around (in Yaouh, too)
>>> * skipping files modified recently
>> How recent would that be?
>> I run yaouh to get the latest tiles where I have updated the map. Of
>> course, this is often the same tiles as I refreshed a couple of days
>> earlier. So I think this has to be optional. Some kind of uses need to
>> check fairly new tiles.
> 
> yep, of course optional and as you said, an addition to be able to
> download only tiles updated less than D days would be nice, too, I
> guess..
> 
>>> * forcing download empty tiles
>> What does that mean?
> 
> For example download every tile that has 2 (or 3 or four) neighbors
> downloaded to 'fill the gaps' in the map.
> 
Ah, excellent!
It'd also be nice to have an option for automatically "zooming out".
That is, if I have a bunch of tiles at zoom 15 (downloaded using 
tangogps perhaps) then I want the zoom 14 tiles covering the same area, 
as well as the zoom 13 tiles, and so on all the way up to the top.

Of course, the number of tiles quickly gets lower as one goes up, and 
usually hits a tile that is there already after a few levels.

>>> Does someone actally know how much load it creates on (new :) OSM
>>> servers to update X mb of tiles with y% to be updated? Are there still
>>> ways to decrease this?
> 
>> So with these numbers, you get 5X+10Xy kB or (5+10y)X kB to transfer.
> 
> So 300MB of tiles with 30% updated it would generate (5+10*30)*300 kB
> = 89MB or so.. ok.. I wonder if it's ok for OSM people if people start
> doing it like this a lot more than they now do.

If people start doing this a lot, then transparent proxies at the 
various ISPs will take much of the load. :-)


Another thing that'd be nice to have, is duplicate tile detection.
There are a lot of "sea" tiles, "empty land" tiles, and probably some 
tiles containing only forest or similiar. This could save lots of space, 
but not download time. It'd still be necessary to check if "empty land" 
suddenly isn't empty anymore.

Helge Hafting