Maps show Access Points at incorrect locations (by 300m)

[NetBandit]

Howdy,

I've posted about 1000 WiFi AP's so far. What I am noticing when I look at known WiFi AP's on the maps generated by the wigle.net site, is that they are pushed about 300m NE of where they should be on the map.

For example, my AP shows up on the next street over, instead of the street I am on, which I estimate at about 300 meters. It looks like all the AP's I've submitted are showing up incorrectly.

Additionally, when I upload the same netstumbler files to www.gpsvisualizer.com, they are correct.

-NetBandit

[bobzilla]

GPS visualizer uses other, professionally rendered maps based on very high resolution data sets. We have data from the U.S. census bureau, which may not be as exact. Also we are triangulating points based on many observations from different users.

That said, there could be a bug in the rendering code which we wrote, if you could give an exact, simple case showing the problem I can track it down and see if it's the best we can do, or if there's a problem with our code.

Thanks!

[NetBandit]

Bob!

Thanks for your quick response.

Check the location of SSID 92882 (uploaded by NetBandit) and compare that to this picture, generated by gpsvisualizer.

http://www.octu.com/home.jpg

-NetBandit

[bobzilla]

That point currently has 8848 gps located observations (all from you , so it makes sense that it would be a few hundred meters away from a single observation.

[NetBandit]

8000 is way too high! I think 80 is even too high. Either way, it doesn't account for a 300m distance offset.

-NetBandit

[bobzilla]

Keep in mind that an observation is lat, long, and signal. There are 222 distinct lat/long observations for that point (again, all from you). So depending on which one of those you sent to gpsvisualizer it will be different then the filtered / weighted average of all of that combined.

[NetBandit]

It's not just that SSID that is having issues... its EVERY SSID (i've posted) that is being mapped incorrectly. Not only that, but they are all off by about the same amount, 300 meters.

-NetBandit

[uhtu]

adam (the gpsvisualizer guy) is probably using Best Lat/Lon from your .ns1 files (we use all of the observations)

do you see the same 300m difference for your observations from

ssid: linksys mac: 00:06:25:e6:48:fb

(which only has two observations in your NS1 file)
?

[NetBandit]

Heh. It ought to be fun finding that linksys ssid/mac... I'll post it up once I find it. Fortunately, I've saved all my netstumbler files.

-NetBandit

[NetBandit]

<bump>

i need to do this soon.

[wrzwaldo]

What datum is your GPS set to? My AP is spot on here in WiGLE World.

[Guest]

Errr nevermind about the datum I was thinking of something else.