Obstructions of the sensor can lead to unwanted tracking movement

Since we track head movement detecting certain facial points, bringing up a glass or something else in front of the tracker will confuse the hedgehog out of it.

Solution? If you want to drink out of a glass for example, toggle head tracking on/off using a hotkey (if available) or do what I do, use a really long straw! Hey, if it works it ain't stupid.