Calculate compass heading from DeviceOrientation Event API

Question

For an augmented reality web app for smartphones I\'m trying to calculate the compass heading when the user is holding the device in their hand, with the screen in a vertica

Answer 1

I have also played some with the DeviceOrientationEvent (might adopt you formula...) and seen similar problems from time to time. You might wanna try a calibration as in this video. You could search youtube for more examples.