I remember being really amazed that I could stand in place and turn around and see my arrow on google maps turn with me. It seemed crazy it had that much precision.
Many smartphones contain miniaturized microelectromechanical systems (MEMS) magnetometers which are used to detect magnetic field strength and are used as compasses. The iPhone 3GS has a magnetometer, a magnetoresistive permalloy sensor, the AN-203 produced by Honeywell. In 2009, the price of three-axis magnetometers dipped below US$1 per device and dropped rapidly. The use of a three-axis device means that it is not sensitive to the way it is held in orientation or elevation. Hall effect devices are also popular.
I remember being really amazed that I could stand in place and turn around and see my arrow on google maps turn with me. It seemed crazy it had that much precision.
They don’t. There’s typically a compass in phones that provides information useful in determining direction.
https://en.wikipedia.org/wiki/Magnetometer
Oh interesting. I guess it makes sense. Much simpler solution with high accuracy.