Re: Tiles and zoom and some out of topic and long


Lynn Deffenbaugh
 

Fred Hillhouse wrote:
I haven't connected to a TNC or GPS yet since the machine doesn't connect to
either, nor will it ever. I plan on moving everything to a laptop this
weekend. This laptop has no internet connection except WiFi on my network.
The laptop is an old Compac Armada M300. It will be connected to a Tracker2
in the vehicle and any helpful tips would be appreciated. Of course I can
always experiment too. I do have an NMEA spigot on my OT2 as well as the
standard serial port running KISS.
If you want APRSIS32 to be generating beacons, you'll need to feed it
NMEA GPS on one port and the KISS on another. I don't interleave the
two. Of course, if you want to use APRSIS32 and can configure the OT2
to forward internally generated beacons out the KISS port, you can use
just the single connection.

I saw this embedded in the Digest version:
"I'm not even sure the program can total space utilization over 2GB as I'm
not sure how big my variable and never expected someone to download that
many tiles before the purger started removing old ones!"

Do you have a tile limitation with the Windows version? I would probably
only limit tiles to drive space. I am finding I will more trips coming up
and it would be nice to not lose previous downloaded tiles.
The 2GB report was reading the wrong numbers somewhere. I currently
have no limits on anything, but have a ToDo item to stop the tile
downloader if the free space on the target drive falls below some
configurable limit. The most I've ever consumed on my laptop with
browsing around the world and zooming in and out all over the place was
500MB or so.

A tile grabber utility would be useful for people without a mobile internet
connection. If there is one, sorry, I didn't see it. There is more
discussion concerning this below about what I have used and have done in the
past.
APRSIS32 includes the ability to pre-fetch tiles as well as the ability
to turn off the tile fetcher and set the maximum age of the cached
tiles. You are in control, although the tile age setting requires a
manual edit of the XML configuration file at the current time.

Have you considered the USGS tiles from the TerraServer as well? This might
be a very useful tool for SAR.
Many other on-line tile sources have restrictions that I could not (in
conscience) live with. I do not remember what all I looked at, but
OpenStreetMap.org was the only one I found that was EXPLICITLY open to
everything I was doing and planning to do with map tiles (real-time GPS
use, local caching, pre-fetching). And on top of that, if there were
errors in a user's area, they could just sign up at OSM and put the fix
in for themselves!

Have you considered being able to use scanned maps? I recently checked out a
universal map downloaded. I have made a couple of maps using a variety of
tiles. SAR might find this useful as well.
I have a ToDo item to support UI-View-type tagged images as background
maps. If you've got 'em, I'm hoping to be able to use 'em.

I use ExpertGPS (E-GPS) for the majority of my mapping needs. Actually, this
is what I compare all other map software to. I have the GIS and CAD option
pack. I have been using it for almost as long as it has been out.

My E-GPS topo and aerial tile collection is a good size.
Type 1 (aerial) 3.79GB on disk in 442,587 Files, 72 Folders Type 2 (topo)
5.18GB on disk in 350,089 Files, 65 Folders Type 4 (urban) 68.2MB on disk in
11,488 files, 26 folders
Given that data size, it sounds like an expensive program to be
comparing "all other map software to"? Remember, APRSIS32 isn't
intended to be a mapping solution, it's an APRS communications solution
that happens to support maps as backgrounds for the realtime data display.

I have grabbed most of the tiles in the area I travel in on a regular basis
(commuting, day trips and camping). I also grab tiles along the routes of
longer trips, such as my trip to Arkansas. If your software could use these
tiles as well... ;)
My software will use any 256x256 tiles that adhere to the "Slippy Map"
tile naming and hierarchical store format. See
http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames for more
information. Just be aware that if you point APRSIS32 to another
hierarchy of map tiles, the purger might delete things that you wanted
to keep and the fetcher may fill in any holes from OSM!

I also have a collection of scanned maps that provide additional
entertainment. I am now experimenting with the universal map downloader to
create a 'scanned' map.
Be aware that some of the new "universal map downloader" software goes
directly against the licenses provided for some of their on-line data
sources. I specifically avoided any complicancy (sp?) with such
approaches as I have no desire to be party to a suit involving my
software as an "enabler" of copyright violations. Hence my support for
only OSM.

The E-GPS tile tool as a rectangular box that one draws on the screen and
the selected resolutions are auto magically downloaded. This usually ends up
with a nice collection of tiles that are not needed. Or one can just update
the location on the screen and tiles are downloaded. I recently have put
together a program to simulate a GPS so that E-GPS will get the tiles as the
position is updated. I have to run a route multiple times to get the
different resolutions but it only gets those that are needed to fill the
monitor and a few extra. I can provide a better description of my process if
needed.
Yes, can you tell me if it covers the entire area at all of the selected
resolutions with the accompanying geometric expansion of the number of
tiles per layer? Or does it keep a constant area as it zooms into the
extended detail? APRSIS32 will fetch the current zoom level and the
ones above and below it (4x below) as you drag the screen around. If
you wait the for yellow circle (background fetch queue progress
indicator) to finish expanding, before dragging again, you can manually
fetch two levels of maps. Your GPS simulator will do the same thing,
provided it moves slowly enough for the fetcher to keep up.

I have also played with USAPhotoMaps so I have a tile collection for that as
well. Someone wrote a tile grabber that works, mostly. There is a bug or
two. It only works within a UTM zone at a time and with a limited number of
points for routes.
UTM Zone? I'm not familiar with that term?

Appreciate your work on this software!
And I appreciate the considered questions and suggestions, as long as
you understand that I might take them or leave them on the table!

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

Thanks!


Best regards,
Fred, N7FMH



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