Does Geotagging equal real GPS?

Discussion in 'iPhone' started by frosse, Jun 3, 2008.

  1. frosse macrumors 6502a

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    #1
    I read about geotagging being in the latest 2.0 firmware and I know that there is cell-tower based "non-GPS" via Google in the current phone. However, isnt the current "non-GPS" way too inaccurate for geotagging?

    what If I'd like to take a picture at a monument and geotag it, and due to ****** celltower based technology the geotag gets mapped waaay off its correct location :confused:
     
  2. BongoBanger macrumors 68000

    BongoBanger

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    #2
    Triangulation isn't really that useful for precise location, especially if you're in an area where the cell towers aren't that close together. GPS gives a better fix and AGPS even better than that.
     
  3. frosse thread starter macrumors 6502a

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    #3
    Does the current iphone use triangulation?

    What is AGPS?
     
  4. BongoBanger macrumors 68000

    BongoBanger

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    #4
    The current iPhone will use triangulation. AGPS is Assissted GPS which means it uses a combination of both triangulation and GPS which means you get a much quicker and more accurate lock on.

    If iPhone 2.0 has GPS it's almost certain that it'll use AGPS too.
     
  5. frosse thread starter macrumors 6502a

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    #5
    My real question is whether a company would feature geotagging without GPS?

    As I've said before, triangulation seems too inaccurate :(
     
  6. BongoBanger macrumors 68000

    BongoBanger

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    #6
    I would doubt it as it wouldn't make sense at all to do so - a lot of those tagged photos may be in out of the way locations where cell coverage may not be great. You'd need GPS to make it accurate enough.
     
  7. kdarling macrumors demi-god

    kdarling

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    #7
    As others have pointed out, you can have all sorts of meta tags. Doesn't mean they'll be used. But it's a good guess they will in this case.

    Corrections for everything else:

    Triangulation: Google maps does not triangulate cell towers. It simply gives the location of the one you're connected to.

    A-GPS: Was more important back when GPS chips were more expensive and less powerful. The phone gets various aid from the carrier servers, such as rough starting location from the tower, satellite info, all the way up to doing the actual calculations from raw signal data.

    E-GPS: The latest thing to have, it gives an instant first fix supposedly using actual tower triangulation (unlike all the others above) then quickly goes for a GPS fix.

    If you wanted a maximum capability system, a combination of Skyhook WiFi and eGPS might make sense.
     
  8. QCassidy352 macrumors G3

    QCassidy352

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    #8
    I don't think this can be right. If it were only the location of the cell tower, it wouldn't change block by block as you move, and mine does. In fact, in downtown city areas, it is extraordinarily accurate, almost always putting me on the exact intersection I'm standing at.
     
  9. frosse thread starter macrumors 6502a

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    #9
    Which is most likely to be used in the iphone?
     
  10. StoneGaijin macrumors regular

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    #10

    Agreed,

    the current Google "triangulation" that is on my iPhone is accurate within a few doors down from my house, and moves when I move. If I'[m a block away or even a half block, it knows once I push the button again.
     
  11. earnjam macrumors 6502a

    earnjam

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    #11
    I think the current version actually uses trilateration. Triangulation uses angles and one known distance. Trilateration uses at least 2 known reference points and the known distance between them and your position. With 3 points and precise distances you can get an exact location. In this case, the distances are not precise, so they have to give you a range.

    So it takes 3 close cell towers, figures out a distance range you could be from each one and creates a circle from that where you could be anywhere inside of.

    http://en.wikipedia.org/wiki/Trilateration


    http://en.wikipedia.org/wiki/Triangulation


    I don't think it can measure angles...
     
  12. kdarling macrumors demi-god

    kdarling

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    #12
    Cities can have lots of mini cells. Checking a map of downtown Boston, I see 55 actual towers and over 1,000 building antennae sites within one mile.

    Google Maps does not triangulate

    Carriers do not give out information on their towers. Not only would it give away coverage information, but carriers like to sell their own location services.

    So Google collects tower locations and rough coverage maps whenever a person with a GPS-equipped cell phone uses their tool.

    As for "triangulation", most civilians think of using signal strength. That' s pretty inaccurate, even if you somehow got access to the tower signal parameters.

    The more accurate locating methods use signal timing of some form. And that requires carrier information and cooperation.

    That's why eGPS uses tower signal timing, and requires that the carrier use special eGPS servers.

    Kevin (former Army Sergeant and direction finder )
     
  13. frosse thread starter macrumors 6502a

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    #13
    Okay this is very confusing for me. Lets answer my questions instead :D

    1. Can Google Maps (iphone version) be used with regular plain ordinary common GPS?

    2. Referring to #2, Any downsides of using Google Maps?

    3. Which is the best: GPS, A-GPS, E-GPS, other?

    4. Referring to #3, which is most likely to be used?

    5. What kind of system does, for example, Nokia N95 use?

    6. ?
     
  14. earnjam macrumors 6502a

    earnjam

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    #14
    1. Based on the article linked by kdarling...I would lean toward yes. They might make some mods to it, but I don't see it going anywhere.

    6. Yes
     
  15. kdarling macrumors demi-god

    kdarling

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    #15
    Sure. Google Maps was being used on other phones with/without GPS a year before the iPhone.

    Well, GMM is not meant for realtime navigation. Most phones use something like the Tom-Tom mobile application, with full onboard maps, and voice prompts.

    Depends on your location (sorry - grin). E-GPS looks sweet, at least around your local carrier. Out in nowhere land, plain GPS is needed.

    Checking the ATT registered developer site, they list three location service methods: GPS puck. Standalone GPS chip. And a hybrid method using A-GPS along with Cell ID or enhanced Cell ID.

    But then, there's probably only one iPhone model being made, which means we can't just think about ATT.

    I would not be suprised if Apple didn't include a combination of methods, as suggested in a previous post. At the least, I speculate that it'll work in standalone mode, no matter what other methods are used.

    Sorry, don't know. I'm sure that's findable on the web.
     
  16. frosse thread starter macrumors 6502a

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    #16
    Okay, nice. Googled it and found some screens of it, looks plain and nice.


    Will we see some sort of SDK project from TomTom or Garmin etc developing a true GPS software? Maybe Google has made a deal with Apple thats based on Googs exclusivity for maps/gps? Maybe TomTom or Garmin has too.

    Whats the difference between TomTom's maps and Googs?


    So E-GPS is plain satelite GPS + the tower thing? That would be the best choice I guess b/c when there are no towers the ordinary satelite GPS kicks in, right?

    Since its time for the rest of the world I guess that not only ATT is taken into consideration by Apple regarding GPS-features.

    How accurate is satellite GPS?

    I wonder if AT&T is the largest object here or the European market?
     
  17. BongoBanger macrumors 68000

    BongoBanger

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    #17
    The Nokia N95 uses AGPS. You can switch the assist off though.

    Google maps works fine with the GPS too although most folks use Nokia Maps because it has optional voice navigation.
     
  18. kdarling macrumors demi-god

    kdarling

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    #19
    The latest GMM for other devices has the pins dropping in and everything. If you have a touchscreen, it slides around the same, but has zoom/unzoom buttons.

    There are two main map providers in the world. NavTeq (many think it's the best) and TeleAtlas (coming up fast).

    Google web maps use NavTeq maps, and Google mobile clients get access to TeleAtlas maps. (The reason supposedly is that NavTeq felt that allowing zillions of clients to directly access it, would somehow lower its data value.)

    Having control of map data is a very desirable power.

    So TomTom bought TeleAtlas. And Nokia bought NavTeq (if the EU approves). Garmin signed a longterm deal with TomTom for map access.

    TomTom is very popular on other world smartphones, so it would not be surprising if they did an iPhone port. It's usually available on SD card or DVD.

    Edit: Something interesting about TomTom on phones vs the usual iPhone UI: on Windows Mobile phones, the navigation instructions remain onscreen even while you're answering phone calls or seeing SMS texts. Clever. But if the iPhone requires apps to shut down during calls... hmm.

    Right you are. The GPS kicks in within seconds even with the towers, but it can operate standalone as well. (I'd hate an aGPS solution only, since I like to boat.)
     

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