Do you think GPS can be three-dimensional? (Tracking by elevation?)

Discussion in 'iOS 9' started by venividivigor, Mar 17, 2016.

  1. venividivigor macrumors 6502

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    #1
    Just a thought, I was dining in a restaurant in downtown, and the tower had several different stores so it can't be more specific when labeling a location I was at when taking photos.

    How awesome would it be if it were able to guess the specific store you were at by elevation?

    Since the new phones do track elevation and GPS... I feel like that would work. But it probably sounds too complex, but you never know.
     
  2. Armen macrumors 604

    Armen

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    #2
    It's possible but I guess businesses or landmarks would have to be registered with elevation coordinate as well.
     
  3. Merkie macrumors 68020

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    #3
    GPS has been able to measure elevation since the beginning.
     
  4. Julien macrumors G4

    Julien

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    #4
    Yes, it is just not as accurate and requires at least 4 satellites to calculate elevation. Here is a white paper.

    http://gpsinformation.net/main/altitude.htm
     
  5. Max(IT) Suspended

    Max(IT)

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    #5
    Gps is three dimensional by definition.
    The issue is on the software side.
    --- Post Merged, Mar 18, 2016 ---
    It actually is very accurate, but the matter is more complex than that (gps use a different reference system, usually, WGS84).
    I work with gps on a daily basis, and I can locate a point in space with a precision of a few centimeters or less.
     
  6. Silvrbill macrumors member

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    #6
    Many different stores can occupy the same location at different times.
    The building will (possibly) be there much longer than the individual stores inside.
    Can you imagine trying to keep up with the physical address of each and every business in the world when they're relocating all the time?
     
  7. Max(IT) Suspended

    Max(IT)

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    #7
    If we are speaking about gps positioning INSIDE buildings, it is very difficult to obtain an accurate fix
     
  8. t0mat0 macrumors 603

    t0mat0

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    #8
    Then use the barometer in conjunction? It's accurate to within basically a floor of a building.
     
  9. electronicsguy macrumors 6502a

    electronicsguy

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    #9
    A barometer measures air pressure. You could do it outside, by going on the roof and measuring the air pressure to infer height. But inside the building, due to ventilation, etc. the air pressure will not necessarily follow the same laws as outside.
     
  10. bruinsrme macrumors 603

    bruinsrme

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    #10
    Let me assure you gps is able to calculate elevation very accurately since the mid 80's.
    I knew exactly how much mast was Visible. That is all.
     
  11. LoveToMacRumors macrumors 68020

    LoveToMacRumors

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    #11
    you guys should watch the movie
    Paranoia
     
  12. campyguy macrumors 68040

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    #12
    Hey, ya'll. From a long-time civil engineer/surveyor, stop thinking in terms of "GPS" - start thinking in terms of GNSS. The subsets of GNSS data are made up of GPS, GLONASS-K, rotation parameters of the Earth, BeiDou, QZSS, Galileo, and SBAS.

    GNSS has been around in one form or another since 1994, when I started laying out my first light rail alignment.

    http://www.igs.org
     
  13. t0mat0 macrumors 603

    t0mat0

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    #13
  14. Julien macrumors G4

    Julien

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    #14
    Didn't say it could not calculate elevation accurately. Paired with a barometer (like the iPhone 6> has) and locked on to at least 4 satellites it can be very accurate with elevation calculations.
     
  15. Max(IT) Suspended

    Max(IT)

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    #15
    Still quite difficult inside a building.
    Theoretically feasible, it should be implemented in both hardware and software side.
    --- Post Merged, Mar 20, 2016 ---
    you are correct, but you are opening a quite complex matter here.
    You should explain what an SBAS is then, and maybe introduce the concept of GBAS also ;)
     
  16. Rhonindk macrumors 68030

    Rhonindk

    #16
    Great topic and thought.
    Unfortunately, barring a breakthrough, it will be a bit till we see that level of definition / accuracy on our devices.
    Would be cool if your stock smartphone phone could do that.
     
  17. campyguy, Mar 20, 2016
    Last edited: Mar 20, 2016

    campyguy macrumors 68040

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    #17
    To me, and my counterparts SBAS is not a complex matter - SBAS (Satellite-Based Augmentation Systems) is just a means to augment the accuracy of GNSS. To most, GPS is a catch-all descriptor; to me and my peers GNSS is the total of which GPS is one component (GLONASS-K is another component), and the following other systems are other components.

    Regarding SBAS, in North America it's WAAS (Wide Area Augmentation System - used in aviation, including the aerial photography you see in Apple/Google/MS Maps; look up the Mr SID TIFF file format and you'll see a file format that I've been using for two decades - an example is each "pixel" is equal to 6 inches, in a vector layer embedded in a Mr. SID TIFF file); in Europe, an SBAS system is EGNOS (European Geostationary Navigation Overlay Service) - and there's other systems around the world; an advantage of SBAS is system uptime and better accuracy.

    GBAS is another augmentation system - Ground-Based Augmentation System. This AS runs over VHF, and it's land-based and meant to be accessed by emergency services (often in poor weather conditions) - it works well for both land- and water-based positioning needs. I've needed to access this system - with permission - in areas where access to the clear sky isn't ideal but precision is important, such as on roads in the middle of nowhere. You may not need this type of system on your iPhone but it's a good bet it was used to lay out some of the roads ya'll drive on. And, if you fly, it's a really good bet that the airway landing strip you just landed on utilized this AS to build it out and maintain it...

    Another far-more accurate SBAS used here in the US is StarFire, owned and operated by John Deere - it's been around for about 20-odd years. Companies/farmers can lease access to that system - it's pretty much available around the world. You want "accurate"? How about down to about 4 centimeters in a 24-hour lease period?

    Download, install, and run the now-free Google Maps Pro. As you mouse over a location you'll see elevations "under" your mouse. Each pixel is tagged with data that was supplied by some sort of AS - Google generally identifies the data source(s) as you move around the interface. A lot of that data was accumulated through aerial photos and survey data purchased from local aggregators (like Metro in the Portland Area and King County in the Seattle Area) - they, in turn, purchased that data from companies I've designed with and surveyed with (and lots of other designers). Years before there was a Google Earth, I used Keyhole - which became Google Earth after Google bought it. Now, there's ties to Trimble (which bought SketchUp) - I use Trimble equipment for my layout work, but that's another long story...
     
  18. venividivigor thread starter macrumors 6502

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    #18
    Okay so if GPS can track elevation, then Apple can implement it on Maps if it add Flyover and Streetview for Google Maps. Just like having a compass on your phone, it would be cool to use the barometer to track elevation, or just like you guys are saying, just GPS.
     
  19. Max(IT) Suspended

    Max(IT)

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    #19
    As pointed out, it would be difficult for it to work inside multiple floors buildings, where the difference between one floor and another is just a few meters and he GNSS signal is weak. Other than that, who mapped buildings floors ' heights according to WGS84 ?
     
  20. campyguy macrumors 68040

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    #20
    Sigh.

    "GPS" is just a tool, like I wrote earlier, a subset of positioning tools used for geolocation. "GPS", the generic version most people allude to is accurate to 6-to-7 meters - that's about 18-to-22 feet. And, that's on a good day when there aren't any atmospheric anomalies or we're being blocked or dumbed-down (to a degree) by some governmental entity or trees (or concrete or metal roofs or.....). Get over "GPS"!!!!!!!!!!!!!

    Like GNSS, iPhones use "GPS" as a subset to locate its users. A-GPS and wifi are two other geolocation methods used by Apple to find us in the greater schema of things. Google has its own API for this kind of service called Indoor Maps, and there's maybe 10k+ subscribers that provide data around the world - Apple isn't one of them. Before you despair...

    There's an app on the App Store named Indoor Survey that isn't available via a search - you need a direct link and a subscription - and it's been on the AS for about 6-7 months. I am not violating my developer TOS with this link - so, maybe this will give you hope that Apple is "on it"...
    https://itunes.apple.com/app/id994269367?mt=8
     

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