On Saturday, March 31, 2018 at 2:34:12 AM UTC-4, Ragnusen Ultred wrote:
Am Fri, 30 Mar 2018 23:27:30 -0600, schrieb rbowman:

Basemaps for an area can be downloaded for local use
but I don't know about the SSID position information.

The last I checked this process was years ago, but what the process was, as
I recall, was you first get a free key from Google.

Then you use that key to query an online database of BSSID location
information that Google provides to all free of charge.

As a rudimentary security measure that I doubt Google Maps has to follow,
you have to give it TWO BSSIDs which must be in close proximity to each
other in the Google database, and a signal strength (which can be bogus).

Under those circumstances, as I recall, Google will give you the location.

But all that only works if you're already on the net, which is not possible
for a tablet that has no cellular capability and which is driving down the
road (unless it's fleetingly connecting to unsecured wide-open access
points).

Hence the question is how does Google /still/ know your location?

When you have it working without cellular, without GPS, how well does it
track? If it works just by knowing which wifi spots it sees, it would
seem to me it would be quite erratic in the typical urban setting.
For example, going down a highway, with GPS, if I make a left turn
it knows instantly. If it's just using which wifi it sees at the moment,
then it would not know that I turned for some decent interval and
I'd expect that it would instead show you continuing on the highway,
then maybe 1000 ft later, suddenly correct and have you instantly
jump from the highway to the side street. And by then you could be
onto a side street and it wouldn't know that either. Do you see that?

If not, then it still remains how it can now accurately where you are.
I can see using wifi spots for general location to an approximate area,
but not for showing an accurate route when there are quite a few possible
streets, roads, parking lots, etc that you could be on.