Trails across map pointing to zero/zero lat/long

[daveemtb]

I have observed on the web map that there are trails from large cities to the point where the Greenwich Meridian crosses the equator (ie lat/long both=zero). These cross oceans, deserts etc and are clearly erroneous.

It seems to me that these must be caused by points erroneously being reported with zero/zero lat/long and being interpolated with the real positions, with the positions on the trail being dependent on the relative signal strengths. Some GPS chipsets erroneously give zero/zero locations occasionally, so some way of dealing with these is needed.

Can I suggest that all GPS points at zero/zero lat/long be deleted or at least excluded from interpolations?

I have also noticed a few other odd trails across oceans, some of which are curved. Not sure what these are caused by. There are some around Hong Kong, and one from France into the Med Sea.

Also, I have some other suggestions for improving accuracy - if there are positions reported for the same BSSID that are more than an adjustable threshold apart, then some kind of error handling is needed. It may be that someone has moved the Wifi AP, in which case the older locations need to be ignored, or it may be that one of the GPS fixes was widely erroneous. Alternatively it is possible that it is a mobile access point, eg a mobile phone working as a Wifi hotspot. Not sure what the best way of handling this is, but interpolating the positions seems pretty meaningless!

[AZ_WD'er]

Some AP's actually move on a very regular basis. I actually logged the wifi signal of the AP's on both the Norwegian Spirit out of New Orleans to Mexico and the Norwegian EPIC out of Miami to St Marteen while on cruises last year. It did look funny to see the number of points it put up. I also logged the AP's on the RCCL Voyager of the Seas a few times between Barcelona Spain and Galvaston Texas a few years ago.

One could also catch the wifi signals off airliners, likely only near lower altitudes depending on range. And consider all the mobile hotspots on cellphones too.

So AP's can actually move.

[KH]

Also a datapoint: I was testing the wardrivebox with a new GPS and noted that it was possible to get the answer "Lat=0.000,Long=0.000,Fix=2D" from the GPS sometime during the process of acquiring a first fix after unboxing. So those locations would be used in the interpolations of the location.