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To enhance presence, facilitate sensory motor performance, and avoid disorientation or nausea, virtual-reality applications require the percept of a stable environment. End-end tracking latency (display lag) degrades this illusion of stability and has been identified as a major fault of existing virtual-environment systems. Oscillopsia refers to the(More)
We measured the gain and phase of horizontal and vertical vergences of five subjects as a function of stimulus area and position. Vergence eye movements were recorded by the scleral search coil method as subjects observed dichoptic displays oscillating in antiphase either from side to side or up and down with a peak-to-peak magnitude of 0.5 degree at either(More)
Virtual reality displays introduce spatial distortions that are very hard to correct because of the difficulty of precisely modelling the camera from the nodal point of each eye. How significant are these distortions for spatial perception in virtual reality? In this study we used a helmet mounted display and a mechanical head tracker to investigate the(More)
The effect of field size, velocity, and visual fixation upon the perception of self-body rotation and tilt was examined in a rotating furnished room. Subjects sat in a stationary chair in the furnished room which could be rotated about the body roll axis. For full-field conditions, complete 360 degrees body rotation (tumbling) was the most common sensation(More)
We measured the gain and phase of vertical vergence in response to disjunctive vertical oscillations of dichoptic textured displays. The texture elements were m-scaled to equate visibility over the area of the display and were aperiodic and varied in shape so as to avoid spurious binocular matches. The display subtended 65 degrees and oscillated through(More)
In order to measure the perceived direction of "up", subjects judged the three-dimensional shape of disks shaded to be compatible with illumination from particular directions. By finding which shaded disk appeared most convex, we were able to infer the perceived direction of illumination. This provides an indirect measure of the subject's perception of the(More)
AQUA, an amphibious robot that swims via the motion of its legs rather than using thrusters and control surfaces for propulsion, can walk along the shore, swim along the surface in open water, or walk on the bottom of the ocean. The vehicle uses a variety of sensors to estimate its position with respect to local visual features and provide a global frame of(More)
The perceived direction of up depends on both gravity and visual cues to orientation. Static visual cues to orientation have been shown to be less effective in influencing the perception of upright (PU) under microgravity conditions than they are on earth (Dyde et al., 2009). Here we introduce dynamic orientation cues into the visual background to ascertain(More)
We measured the effect of the orientation of the visual background on the perceptual upright (PU) under different levels of gravity. Brief periods of micro- and hypergravity conditions were created using two series of parabolic flights. Control measures were taken in the laboratory under normal gravity with subjects upright, right side down and supine.(More)
Supine subjects inside a furnished room in which both they and the room are pitched 90 degrees backwards may experience themselves and the room as upright relative to gravity. This effect is known as the levitation illusion because observers report that their arms feel weightless when extended, and objects hanging in the room seem to "levitate". This(More)