RE: Spain Tile Caching
- Actually, I did only ask the question more out of interest rather than a
push to a particular direction. But, I do have a bridge to sell as well if
you are interested. ;)
I flew out to Arkansas on Saturday and my daughter met me at the airport and
we came straight home from there. We got home Sunday night, 25 hours of
driving later. It was a good trip!
In advance, I created a GPX file for the planned route using GMap2GPX &
Notepad. Actually I created several different routes. I then fed only one
route [I-81] through my "GPS simulator" and let APRSIS32 do its thing. It
took awhile. I set the zoom level at 14 so I could have a larger swath at
level 15 which would allow for food/fuel/motel hunting as needed. Street
names are available at that level in most if not all areas. I only sent a
position every 5 seconds or so. It gave the software enough to grab to tiles
that way and have a bit of dead time. I let it run unattended so it did not
impact what I was doing. By running it slow, it should not have caused a
large load on the servers either but I have no way to know that for sure.
I ended up not having a tracker to run and not using the laptop either. But,
I have the tiles for my next trip [next month] which will be in a tracker
Actually, this method seems to grab less tiles than if I used the Prefetch
Tiles option. I think I only got 14 and 15 (2 levels) while cruising around
at 14. The prefetcher grabs 4 levels. I try to remember to turn off fetching
once I am done or I get level 16 tiles which I don't need for general
As you can see, I have worked out a plan to grab tiles anyway. I also have a
procedure to grab 1/4 of a grid square at a time. It requires more effort
but it is not too obnoxious. The procedure marches APRSIS32 around the area
in 1 degree steps. At 5 seconds per position, the tiles in a 1/4 grid square
area takes 5-6 hours. I am only grabbing blocks of areas that I will visit
in the next couple of months. As I visit more areas in the future, I will
grab additional tiles.
I can't imagine that I am the only one that pre-fetches tile over a large
area for offline work. I would suggest that when you have a "updater"
running, you allow for updating over a period of time. Updating 200K files
at 1.3GB over a period of time would be better than as quick as possible. I
did grab these files over several weeks so as not to create too much of a
> -----Original Message-----
> From: Lynn W. Deffenbaugh [mailto:KJ4ERJ@...]
> Sent: Tuesday, June 15, 2010 17:04
> To: Fred Hillhouse; firstname.lastname@example.org
> Subject: Re: Spain Tile Caching
> The hard way! I've turned off the purger and have been doing
> Screen / Map / Prefetch with various chunks of the country
> visible. I've zoomed in on the major cities 2-3 levels (just
> to fill the screen) and done another Screen / Map / Prefetch.
> This was all on my phone which now has
> 20,249 tiles over 113.64MB. Remember, each Prefetch pulls
> details from the current level down 3 additional levels.
> Then I fired up an APRSIS32 on my laptop and gave it a
> different OSMTiles tree (my other instances all share a
> single tree). There I got REALLY carried away with the
> Prefetch. That instance has 127,491 tiles over 393.02 MB.
> My plan was to copy that tree onto the micro-SD card that
> goes into my phone, but it now appears that I'll have
> cellular data over there, so I'll probably just let it pick
> up more detail as we travel.
> I know that last sentence is what you didn't want to hear,
> but I haven't yet given up ideas on prefetching and status
> checking/refreshing the OSM tiles. Someone's been actively
> editing streets in my city, so I'm really getting a
> motivation to get some sort of updater going. Aging out in a
> month is just way too long.
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
> PS. Copied the response to the group in case others are
> interested in prefetch and how it might be used.
> Fred Hillhouse wrote:
> > Hi Lynn,
> > Out of curiosity, how are you caching tiles for Spain? Or are you?
> > Thanks!
> > Best regards,
> > ------------------------------------
> > Fred Hillhouse Jr
> > http://kevan.org/brain.cgi?N7FMH
> > ------------------------------------