[mynameisvlad]

Google doesn't specifically know you stopped at Pizza Hut or the BP garage. It uses coarse location (GPS being too taxing on battery to get constant location updates) which has an accuracy of 100+ meters. So it would know you stopped somewhere around the Pizza Hut, but not specifically that you went inside. Could have just as easily gone to the Tesco next door.

[nick_riviera]

Actually yes it does know I stopped at both of those location.

1. The BP garage has a wireless AP with a known SSID to them. Location services uses this, the cell network and the GPS to build an accurate location. There are no other wireless networks at that location. I was at this location for around 10 minutes. Google location history shows this location on the mark.

2. They know that I was at the Pizza hut because I left a review in Google+ and was approximately near it at the time and stayed in roughly the same location for about 90 minutes. Google location history shows this location on the mark.

It's all about correlating events and data, not specifically accurate bits of data.

Granted these are all assumptions but they would stand as evidence in a court of law.

Now I'm not fussed about this myself as it's something I trade for the service, but the data is there.

[scoot]

Besides which, consumer GPS has a resolution down to 3M, 95th percentile - not 100M [1].

[1] http://www.gps.gov/technical/ps/2008-SPS-performance-standar...

[e12e]

I don't agree with gp's dismissal, but the point about gps and coarse location was that continuously updating gps (for full 3m resolution) would be too taxing on the batteries -- not that gps resolution was poor.

Don't think that applies if parent was using google maps to navigate, though -- how useful would navigation be without correct and updated position? Not to mention wi-fi location, correlation with plus posts/check-ins etc...

[mynameisvlad]

You didn't explain how they knew about the PH/BP, which makes people assume it was due to location data (like your first example).

However, as for comment #1, Google doesn't use the SSIDs to determine locations on mobile, they use the [MAC Addresses](http://static.googleusercontent.com/media/www.google.com/en/...). They do have a database that also includes SSIDs for these MAC addresses, but there could be a dozen SSIDs around you at any given time, and you could be at any one of those businesses. I have already explained that Google uses coarse location to determine your location, not fine because of battery issues (and you can check this in Android, it's listed under the lower-power location use). Coarse doesn't use GPS, and its accuracy is generally 100+ meters because of this. It will know the general area you were at (and, no, it won't know you were there for 10 minutes, as it only picks up your location at fixed intervals which IIRC is above 10 minutes), but it won't know, specifically, where you were in that area.

I will concede on the Pizza Hut location, but it would have only known you were there because of the review, not because of the location (for the same reason as above).

[nick_riviera]

I purposely avoided explaining it to demonstrate a point: the average user doesn't know this or understand it. They understand the outcome only.

Sorry, you are 100% correct with the SSID vs MAC. If I'm in my car with the handset externally powered, does it use course location or does it use all three sources because on KitKat on my Moto G, it gives me the option to use all three at cost of battery life?

I disagree with your assessment of the location ability. It's definitely better than you explain it. I can go through at least 100 previous data points in my history and it's spot on each time.

[MertsA]

The way Google gets your approximate location is not as simple as just sending Google a list of visible access points and figuring out where the Google Maps car was when it saw that access point, it also passes along the signal strength of every access point and because the Street View car is recording signal strength and GPS location for every measurement as it's driving by it allows for a much finer resolution than just a binary "can I see this access point".

Basically, even though there was a dozen access points visible, that increases accuracy, not decreases. Like if your phone reported that it's got the same signal strength for BP and PH it will estimate that you are in between them with other access points helping to conclude that you aren't off to the side otherwise the signal strength to xyz access point would be higher.

In other words, Just sending a list of access points and signal strengths to Google gives them a rather accurate guess as to where you are in the world, much greater than just 100+ meters.

Also, Android can also figure out when you are in a car moving at highway speeds thanks to the accelerometer and is quite accurate at telling when you're walking, jogging, biking, or driving. Enable Google Now on your phone and it will send you a summary of how many miles of what activity you've done in the last month with rather surprising accuracy for me personally.

[threeseed]

You haven't explained why Google wouldn't know about PH/BP.

In Apple's implementation which I do know well the WiFi triangulation is enabled even at the coarsest resolution. Which is obvious since it is low cost. So if indeed there is one SSID/MAC in the area and it is coming from BP why would Google not know this ?

[mynameisvlad]

The presence of a SSID isn't indicative that you went to said business. If I lived above a McDonalds, Pizza Hut, and Subway, all with their respective SSIDs, that doesn't mean I am at any of the businesses. So sure, Google could know that there's a Pizza Hut near you, but they have no way of knowing whether you're actually at the Pizza Hut, or, say, the Tesco next door.

[IvyMike]

If you have an android phone you may want to check out your location history: https://maps.google.com/locationhistory/b/0

Certainly far better than 100 meters in my case.

[mynameisvlad]

I think 100m is the best they can guarantee. You may get better results based on the data they have in your area (especially WiFi triangulation), but it's not guaranteed. In any case, the best they have for me is: http://imgur.com/vVbqSvr which is coarse enough to not actually provide much data. I could have been to any one of a dozen or so businesses in that area.

[IvyMike]

We all know it was Tim Hortons.

[pwnna]

This is by far one of the creepiest things I've seen.

[TeMPOraL]

Also one of the most useful.

Funny thing though - Google could easily blow all those Endomondo et al. "share my running" apps out of the water by just allowing to publicly share a time-delimited subset of your location history...

[threeseed]

I am really confused here. Why would Google Maps not use GPS at its highest resolution ?

[Jach]

No kidding, any Maps user can see their GPS location being collected when they use Maps. I think mynameisvlad may mean they wouldn't necessarily know if you stopped at a specific place as part of the location data collected when you're not using Maps, because in that case it may not use GPS. But I have a nice phone, battery life isn't really a concern to me, some software on the phone probably knows that too, and I don't trust the word of a random person on HN that the software wouldn't do an opportunistic GPS look up at least every now and then. In any case I want my phone to use GPS whenever it can so that it's as accurate as it can be, that's why I have in my settings GPS always enabled, with high accuracy (uses GPS, wi-fi, and mobile networks) and indeed I have Google Location Reporting on as well which looks up my location throughout the day whether or not I'm using Maps.

[nevi-me]

Because in this instance, the argument/discussion is about the phone specifically, not Google Maps. When my phone is on stand-by, like when I'm driving and not using the GPS, the phone will rely on less battery-taxing things like triangulation, Wi-Fi AP's that Google knows (MAC/SSID ?). Google Maps would however use GPS when it is on, not when the user hasn't specifically turned it on.

[threeseed]

> I just drove half way across the UK. Google knows that because I was using Google maps.

I think you're a little confused.

[nevi-me]

> I think you're a little confused.

It's you who's confused (as you said previously, no offence). The post you replied to talked about "I just drove half way across the UK. Google knows that because I was using Google maps", and the mention of not using highest resolution is about Google (not Maps) using other means to determine location. Clear difference between Google Maps and Google.

Silly technicalities, don't know what the downvote was for, was only trying to help your initial confusion :)

[hrjet]

> [Google] uses coarse location (GPS being too taxing on battery to get constant location updates) which has an accuracy of 100+ meters.

You mean Google Maps -- the app -- doesn't use location data from GPS? I am pretty sure that isn't true.

If you meant Google Maps -- the service -- then the sentence doesn't make much sense, since it doesn't use any location service on the mobile directly. It is just interfacing with the mobile app over a network.

[mynameisvlad]

No I mean Google, the company. Specifically, Google pings your location at intervals (building their Location history, linked above). For this specific use (which isn't tied to Google Maps), it's done through the Google Play Services, which, under the Location setting on your phone is listed as "Low battery use". This indicates that it is not using the GPS chip, but relying only on WiFi and Cell tower triangulation.