Techniques are discussed for creating a rendered view into a 3D scene,interactively based on the locations and orientations of the observer's head and the display surface. Stereoscopic headmounted displays (HMDs) demonstrate a simplified, special case of these techniques, becausethe eyes and monitors move in unison.A largely overlooked classof interactive displays usesthe relative positions between the eyes and monitor as input. These displays can be stereoor monoscopic, fixed or mobile, andthe rendering process should incorporate the correct perspective distortion, which depends on the locations of the viewpoint(s) and the display monitor. Three real-time graphics display systems were prototyped and examined: ahigh-resolution display which corrects the perspective projection based on the location of the observer's eye; the same display, extended to modify the view as the monitor is tilted and swiveled; and a handheid LCD display which can be freely moved and rotated as it d...