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Google explains how it will "dramatically" improve GPS location in urban areas in Android apps



One of the novelties of the latest Pixel Feature Drop was more difficult to see with the naked eye: it was an improved location system, capable of improving precision in specific cases by making use of 3D models of buildings that Google has been adding to its map service for some time.



Users of a Google Pixel 5 and a Google Pixel 4a 5G will be the first to notice the results of this improvement, which is available in the 3,850 cities of which Google has its buildings mapped. According to Google, this system will improve positioning "dramatically" in urban centers with a large concentration of buildings and skyscrapers.






Calculating the rebound



For the ideal operation of GPS positioning systems, the mobile needs to have line of sight with several satellites, something that is especially difficult in the most dense urban areas. What reaches us on the mobile are signals reflected in buildings, and hence the GPS jumps from one place to another, sometimes locating us on the opposite side of the street or a block away.







This is how your mobile GPS manages to locate you with a few meters of error





To fix this, Google has made use of the 3D mapping of buildings from Google Maps, GPS measurements and machine learning. In practice, it is a module within the Google Play Services that corrects those reflected measurements taking into account the 3D models of the city and your current position. This corrected measurement is served via Google's location API to applications and the mobile's GPS hardware driver, reducing curb jump cases by 75%.



Example Google example. In yellow, the real route. In red, the measurement not optimized. In blue, the optimized measurement.


To function, Google Services need download the 3D data of the buildings in your city that are used in the calculations and that, according to Google, should not take more than 20 MB of cache space. This download is carried out if you are in one of the 3,850 cities of which Google has mapped its buildings, including all the main European cities, the United States, Canada, Mexico, Japan, Taiwan, Argentina, Brazil, Australia, New Zealand and South Africa.



These optimizations are available both when using the North American GPS system and their counterparts from other nations such as GLONASS, Galileo, BeiDou or QZSS. Of course, these optimizations are available only for walking routes and not in any type of vehicle.



This second version of the optimization module has already been deployed in the Google Pixel 5 and Google Pixel 4a in the latest Feature Drop, although it will arrive to the rest of Android phones with Android 8 or higher in early 2021. The difference between the first version - the current one - and version 2.0 is that the first one represented a reduction of 50%. In the second version, location errors are reduced by 75% that put you on the wrong side of the street.



More information | Android Developers