One of the most important motions to understand for VR is the vestibulo-ocular reflex or VOR. Hold your finger at a comfortable distance in front of your face and fixate on it. Next, yaw your head back and forth (like you are nodding ``no''), turning about 20 or 30 degrees to the left and right sides each time. You may notice that your eyes are effortlessly rotating to counteract the rotation of your head so that your finger remains in view. The eye motion is involuntary. If you do not believe it, then try to avoid rotating your eyes while paying attention to your finger and rotating your head. It is called a reflex because the motion control bypasses higher brain functions. Figure 5.19 shows how this circuitry works. Based on angular accelerations sensed by vestibular organs, signals are sent to the eye muscles to provide the appropriate counter motion. The main purpose of the VOR is to provide image stabilization, as in the case of smooth pursuit. For more details about the vestibular organ, see Section 8.2.
Steven M LaValle 2020-01-06