Move the phone and the dot stays where it was. Roll the phone and it swings around, because a point in the room does not roll with you.
The faint cross is where the phone itself is pointing. When the two coincide, the dot is home. Tap anywhere to recentre.
Axis calibration runs quietly in the background — it locks on by itself once you have happened to roll and tilt the phone a little.
How far the dot may travel from centre before it stops.
Integrator memory. Longer holds the point better and creeps more.
Raise this if the dot wanders while the phone sits still.
Tilting the phone about your wrist really does move it, so the gyroscope predicts that part and it is subtracted. Set Strength to 0 % to see what it was doing.
The dot turns green when the lock holds it still.
World is correct: roll the phone and the point swings around, because it belongs to the room. Screen ignores roll, which is easier to read while tuning.
Axes: detecting.