Android phone orientation overview including compass

Question

I\'ve been trying to get my head around the Android orientation sensors for a while. I thought I understood it. Then I realised I didn\'t. Now I think (hope) I have a better

Answer 1

Roll is a function of gravity, a 90 degree roll puts all of gravity into the x register.

Pitch is the same, a 90 degree pitch up puts all of the component of gravity into the y register.

Yaw / Heading / azimuth has no effect on gravity, it is ALWAYS at right angles to gravity, hence no matter which way you are facing gravity will be imeasurable.

This is why you need a compass to assess, maybe that makes sense?