The Yaw, Pitch, and Roll of the Head in a Straight Ahead Orientation

Head mounted displays (HMD) are finding increasing use in a great many applications. These HMDs provide information ranging from a simple alphanumeric to complex graphical renderings of real or synthetic worlds. Some of these HMDs are opaque so that the user's vision is completely confined to what the HMD provides; others are see-through so that elements of the HMD may be superimposed simultaneously with the external world. Some see-through HMD applications incorporate graphical elements intended to be in some calibrated registration with elements of the external world such that the relation between the graphic and the world embodies the relevant information. For such displays to function as intended the head yaw, pitch, and roll are important. The present paper reports measures of head yaw, pitch, and roll when the head is in a straight ahead orientation. Volunteers oriented to either a visual or auditory target stimulus presented under a variety of conditions. For some conditions with the visual target, the visual field was restricted to less than 5 degrees (°); for other conditions vision was unrestricted. The auditory targets were presented in complete darkness. At the start of each trial, an acoustic warning signaled the volunteer to turn the head from an initial off-axis yaw and pitch to a target stimulus that defined the straight ahead yaw and pitch. Note that the stimulus left head roll completely undefined. Within- and between-subject head yaw, pitch, and roll statistics are reported and compared for the various stimuli.