Bettering city GPS accuracy on your app


Posted by Frank van Diggelen, Principal Engineer and Jennifer Wang, Product Supervisor

At Android, we need to make it as straightforward as doable for builders to create probably the most useful apps for his or her customers. That’s why we goal to offer the perfect location expertise with our APIs just like the Fused Location Supplier API (FLP). Nevertheless, we’ve heard from lots of you that the largest location problem is inaccuracy in dense city areas, resembling wrong-side-of-the-street and even wrong-city-block errors.

That is significantly vital for probably the most used location apps, resembling rideshare and navigation. For example, when customers request a rideshare car in a metropolis, apps can’t simply find them due to the GPS errors.

The final nice unsolved GPS downside

This wrong-side-of-the-street place error is brought on by mirrored GPS indicators in cities, and we launched into an bold mission to assist resolve this nice downside in GPS. Our answer makes use of 3D mapping aided corrections, and is simply possible to be performed at scale by Google as a result of it includes 3D constructing fashions, uncooked GPS measurements, and machine studying.

The December Pixel Characteristic Drop provides 3D mapping aided GPS corrections to Pixel 5 and Pixel 4a (5G). With a system API that gives suggestions to the Qualcomm® Snapdragon™ 5G Cell Platform that powers Pixel, the accuracy in cities (or “city canyons”) improves spectacularly.

Picture of a pedestrian test, with Pixel 5 phone, walking along one side of the street, then the other. Yellow = Path followed, Red = without 3D mapping aided corrections, Blue = with 3D mapping aided corrections.  The picture shows that without 3D mapping aided corrections, the GPS results frequently wander to the wrong side of the street (or even the wrong city block), whereas, with 3D mapping aided corrections, the position is many times more accurate.

Image of a pedestrian take a look at, with Pixel 5 telephone, strolling alongside one aspect of the road, then the opposite. Yellow = Path adopted, Pink = with out 3D mapping aided corrections, Blue = with 3D mapping aided corrections.

Why hasn’t this been solved earlier than?

The issue is that GPS constructively locates you within the incorrect place if you find yourself in a metropolis. It is because all GPS techniques are primarily based on line-of-sight operation from satellites. However in massive cities, most or all indicators attain you thru non line-of-sight reflections, as a result of the direct indicators are blocked by the buildings.

Diagram of the 3D mapping aided corrections module in Google Play services, with corrections feeding into the FLP API.   3D mapping aided corrections are also fed into the GNSS chip and software, which in turn provides GNSS measurements, position, and velocity back to the module.

The GPS chip assumes that the sign is line-of-sight and due to this fact introduces error when it calculates the surplus path size that the indicators traveled. The commonest aspect impact is that your place seems on the incorrect aspect of the road, though your place also can seem on the incorrect metropolis block, particularly in very massive cities with many skyscrapers.

There have been makes an attempt to deal with this downside for greater than a decade. However no answer existed at scale, till 3D mapping aided corrections had been launched on Android.

How 3D mapping aided corrections work

The 3D mapping aided corrections module, in Google Play providers, consists of tiles of 3D constructing fashions that Google has for greater than 3850 cities all over the world. Google Play providers 3D mapping aided corrections presently helps pedestrian use-cases solely. Whenever you use your system’s GPS whereas strolling, Android’s Exercise Recognition API will acknowledge that you’re a pedestrian, and if you’re in one of many 3850+ cities, tiles with 3D fashions can be downloaded and cached on the telephone for that metropolis. Cache measurement is roughly 20MB, which is about the identical measurement as 6 pictures.

Contained in the module, the 3D mapping aided corrections algorithms resolve the chicken-and-egg downside, which is: if the GPS place will not be in the proper place, then how are you aware which buildings are blocking or reflecting the indicators? Having solved this downside, 3D mapping aided corrections present a set of corrected positions to the FLP. A system API then offers this info to the GPS chip to assist the chip enhance the accuracy of the following GPS repair.

With this December Pixel function drop, we’re releasing model 2 of 3D mapping aided corrections on Pixel 5 and Pixel 4a (5G). This reduces wrong-side-of-street occurrences by roughly 75%. Different Android telephones, utilizing Android 8 or later, have model 1 applied within the FLP, which reduces wrong-side-of-street occurrences by roughly 50%. Model 2 can be out there to all the Android ecosystem (Android 8 or later) in early 2021.

Android’s 3D mapping aided corrections work with indicators from the USA’s World Positioning System (GPS) in addition to different World Navigation Satellite tv for pc Methods (GNSSs): GLONASS, Galileo, BeiDou, and QZSS.

Our GPS chip companions shared the significance of this work for his or her applied sciences:

“Customers depend on the accuracy of the positioning and navigation capabilities of their cell phones. Location know-how is on the coronary heart of making certain you discover your favourite restaurant and also you get your rideshare service in a well timed method. Qualcomm Applied sciences is main the cost to enhance shopper experiences with its latest Qualcomm® Location Suite know-how that includes integration with Google’s 3D mapping aided corrections. This collaboration with Google is a vital milestone towards sidewalk-level location accuracy,” mentioned Francesco Grilli, vice chairman of product administration at Qualcomm Applied sciences, Inc.

“Broadcom has built-in Google’s 3D mapping aided corrections into the navigation engine of the BCM47765 dual-frequency GNSS chip. The mix of twin frequency L1 and L5 indicators plus 3D mapping aided corrections offers unprecedented accuracy in city canyons. L5 plus Google’s corrections are a game-changer for GNSS use in cities,” mentioned Charles Abraham, Senior Director of Engineering, Broadcom Inc.

“Google’s 3D mapping aided corrections is a significant development in private location accuracy for smartphone customers when strolling in city environments. MediaTek’s Dimensity 5G household permits 3D mapping aided corrections along with its extremely correct dual-band GNSS and industry-leading useless reckoning efficiency to present probably the most correct world positioning ever for 5G smartphone customers,” mentioned Dr. Yenchi Lee, Deputy Basic Supervisor of MediaTek’s Wi-fi Communications Enterprise Unit.

Learn how to entry 3D mapping aided corrections

Android’s 3D mapping aided corrections mechanically works when the GPS is being utilized by a pedestrian in any of the 3850+ cities, on any telephone that runs Android 8 or later. One of the best ways for builders to benefit from the development is to make use of FLP to get location info. The additional 3D mapping aided corrections within the GPS chip can be found to Pixel 5 and Pixel 4a (5G) at this time, and can be rolled out to the remainder of the Android ecosystem (Android 8 or later) within the subsequent a number of weeks. We may also quickly help extra modes together with driving.

Android’s 3D mapping aided corrections cowl greater than 3850 cities, together with:

  • North America: All main cities in USA, Canada, Mexico.
  • Europe: All main cities. (100%, besides Russia & Ukraine)
  • Asia: All main cities in Japan and Taiwan.
  • Remainder of the world: All main cities in Brazil, Argentina, Australia, New Zealand, and South Africa.

As our Google Earth 3D fashions develop, so will 3D mapping aided corrections protection.

Google Maps can also be getting updates that may present extra road degree element for pedestrians in choose cities, resembling sidewalks, crosswalks, and pedestrian islands. In 2021, you will get these updates on your app utilizing the Google Maps Platform. Together with the improved location accuracy from 3D mapping aided corrections, we hope we can assist builders such as you higher help use circumstances for the world’s 2B pedestrians that use Android.

Constantly making location higher

Along with 3D mapping aided corrections, we proceed to work laborious to make location as correct and helpful as doable. Under are the most recent enhancements to the Fused Location Supplier API (FLP):

  • Builders wished a neater technique to retrieve the present location. With the brand new getCurrentLocation() API, builders can get the present location in a single request, reasonably than having to subscribe to ongoing location modifications. By permitting builders to request location solely when wanted (and mechanically timing out and shutting open location requests), this new API additionally improves battery life. Take a look at our newest Kotlin sample.
  • Android 11’s Data Access Auditing API offers extra transparency into how your app and its dependencies entry personal information (like location) from customers. With the brand new help for the API’s attribution tags within the FusedLocationProviderClient, builders can extra simply audit their apps’ location subscriptions along with common location requests. Take a look at this Kotlin sample to study extra.

Qualcomm and Snapdragon are logos or registered logos of Qualcomm Integrated.

Qualcomm Snapdragon and Qualcomm Location Suite are merchandise of Qualcomm Applied sciences, Inc. and/or its subsidiaries.

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