Friday, January 22

Google uses its 3D mapping to improve GPS on Android

Google will deploy an update to its APIs in December to allow better geolocation of pedestrians in dense cities. What to avoid seeing his GPS wandering from one side of the road to the other.

GPS geolocation is very imperfect on our smartphones. Sufficient for navigation in a vehicle, it turns out to be much more delicate when one moves on foot and it is not uncommon, in large cities at least, to see the point indicating its position wandering around. ‘side to side of the road, or worse, from one neighborhood to another. Google, however, indicates that it has found the magic algorithm to correct this problem.

Blame it on the buildings

To fully understand the situation, it is important to remember how a GPS works. The smartphone receives the signal from several satellites in orbit which broadcast their position in the sky and the precise time of emission of the signal. As this signal travels at the speed of light, a basic calculation (the travel time of the waves between the time of transmission and the time of reception multiplied by the speed of light) allows us to know the distance between the receiver and satellite. Once this calculation is done for 3 satellites, it is then possible to triangulate the position.

This basic principle is simple to apply when the space around the user is clear, but much more complex when it is cluttered with buildings which reflect the signal. As the latter bounces off several surfaces before reaching its destination, its path is no longer a straight line between the transmitter and the receiver, making it difficult to calculate the position precisely. It is because of this that Google Maps or the Uber app will spot you on the wrong sidewalk.

A solution achievable only by Google

Thanks to its huge database of 3D buildings, raw GPS measurements and a good dose of machine learning, Google has successfully created an algorithm to correct these errors. The precise details of how it worked were not disclosed, however. However, this corrected position will be integrated into Android via the Fused Location Provider (FLP) API, used by a large number of applications to obtain geolocation information.

Starting in December, Pixel 5 and Pixel 4a users should therefore see an improvement in their GPS journeys. The first Google tests seem particularly conclusive as shown by the images below plotting the route taken (in yellow), the route recognized before the application of this algorithm (in red) and the route after the application of the algorithm. .

Obviously, for the GPS position to be improved, it is necessary for Google to have a 3D mapping of the surrounding buildings. So it works in 3850 cities across the globe (large cities with annoying buildings are generally covered). It also works with GPS, GloNASS, Galileo, BeiDou and QZSS satellites. Note, however, that the FLP APIs are integrated into Google Mobile Services, which makes the magic inoperative for Chinese smartphones which are deprived of them.

From the start of 2021, all smartphones running Android 8 or later will benefit from this 3D correction which, according to Google, reduces 75% of positioning problems on the wrong side of the street. You shouldn’t make a mistake when crossing to look for a new job …

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