Showing papers on "Monocular vision published in 1990"

Large-field holographic binocular helmet visor

Abstract: The visor makes it possible to obtain in binocular vision a large field of 60° in the vertical plane and 120° in the horizontal plane. In the case of each monocular vision channel, the visor is constituted by: an image generator such as a miniature cathode-ray tube, for example; an optical relay device; a collimation and combination optical system in which are grouped together a holographic mixing plate for transmitting the landscape channel and reflecting the image channel and a biconvex combining device formed by two holographic spherical optical elements employed on the axis for transmitting the two channels with collimation by diffraction of the image channel. A circular axial zone of zero photometric efficiency is produced in the case of each monocular vision channel and compensated by overlapping of the fields in binocular vision and, in a complementary manner, by the construction of mirror holograms providing variable index modulation.

Visual issues in the use of a head-mounted monocular display

Abstract: A miniature display device, recently available commercially, is aimed at providing a portable, inexpensive means of visual information communication. The display is head mounted in front of one eye with the other eye's view of the environment unobstructed. Various visual phenomena are associated with this design. The consequences of these phenomena for visual safety, comfort, and efficiency of the user were evaluated: (1) The monocular, partially occluded mode ofoperation interrupts binocular vision. Presenting disparate images to each eye results in binocular rivalry. Most observers can use the display comfortably in this rivalrous mode. In many cases, it is easier to use the display in a peripheral position, slightly above or below the line of sight, thus permitting normal binocular vision of the environment. (2) As a head-mounted device, the displayed image is perceived to move during head movements due to the response of the vestibulo-ocular reflex. These movements affect the visibility of small letters during active head rotations and sharp accelerations. Adaptation is likely to reduce this perceived image motion. No evidence for postural instability or motion sickness was noted as a result of these conflicts between visual and vestibular inputs. (3) Small displacements of the image are noted even without head motion, resulting from eye movements and the virtual lack of display persistence. These movements are noticed spontaneously by few observers and are unlikely to interfere with the display use in most tasks.

Monocular stereopsis with and without head movement.

Abstract: Random dots moving with various velocity gradients were presented to observers; the motion was yoked to head movement in one condition and to no head movement in another. In Experiment 1, 12 observers were shown motion gradients with sine, triangle, sawtooth, and square waveforms with amplitudes (equivalent disparities) of 12′ and 1° 53′. In Experiment 2, 48 observers were shown only the sinewave or square-wave gradient of 1° 53′ disparity either with or without head movement so that the observers’ expectation to see depth in one condition did not transfer to another. The main findings were: (1) with 12′ disparity, the head-movement condition produced perceived depth but almost no perceived motion, whereas the no-head-movement condition produced both perceived depth and perceived motion; (2) with 1° 53′ disparity, both conditions produced perceived depth and perceived motion; and (3) when the expectation to see depth was removed, the no-head-movement condition with the square-wave gradient produced no perceived depth, only motion. We suggest that monocular stereopsis with head movement can be achieved without perception of motion but monocular stereopsis without head movement requires perception of motion.

Some visual influences on human postural equilibrium: Binocular versus monocular fixation

Abstract: The importance of vision for postural equilibrium has long been known; traditionally, this visual contribution to the control of posture has been analyzed primarily in terms of optical and retinal phenomena. Recently, however, there has been some suggestion that binocular and monocular fixation of identical stimuli have differential effects. Three experiments were conducted in order to measure self-generated movement (sway during quiet standing) of the body’s center of gravity while field structure, ankle proprioception, and binocular/monocular fixation were varied. Field structure was varied from total darkness, to the presence of single and multiple LEDs in the dark, to full field structure (i.e., the richness of the feedback information was varied). Ankle proprioception was varied by changing foot position from side-by-side to heel-to-toe positions. Results indicate that (1) ankle-joint input is a significant factor in reducing sway, (2) binocular fixation attenuates sway relative to monocular fixation, under otherwise identical visual conditions, and (3) this difference persists in total darkness. Taken together, the data indicate that the visual influence on postural equilibrium results from a complex synergy that receives multimodal in-puts. A simple optical/retinal explanation is not sufficient.

Fundamental monocular/binocular HMD human factors

Abstract: Five laboratory studies were conducted in order to establish image alignment tolerances for wide field of view monocular/biocular/binocular helmet mounted displays (HMD). Apache Helicopter type production HMD oculars were used by night vision trained pilots in the studies, the results of which underscore the operational advantage of maintaining one dark adapted eye, and quantify the pilots' perceptual sensitivities to display system sources of binocular misalignment.

Acquiring 3D structure by controlling visual attention of a mobile robot

Abstract: A monocular vision sensor on a mobile robot for finding and tracking a feature point in 3D space while it moves along a route is described. Visual feedback is used to fix the feature point, called the fixation point, at the image center. The precise information of the camera angular velocity is used for estimating 3D structure around the fixation point to build a local map. Mathematical equations for linear and circular robot motions are given. Experimental results show the validity of this method. >

Detecting orientation of a surface : the rectangularity postulate and primary depth cues

Abstract: Computational metaphors for determining the orientation of planar surfaces represented in line drawings have exploited a postulate that often surfaces are rectangular. Previous research implies that people follow such logic with real surfaces in ecological viewing. However, this research is problematic methodologically and some research does not directly address the issue. The stimuli used in this study were rectangular and trapezoidal; the latter shape was used to mislead with regard to orientation under the rectangularity postulate. Viewing conditions were monocular and binocular, with and without observer movement. The results suggest that the rectangularity postulate was important under stationary monocular viewing but diminished with movement and was not apparent during binocular viewing. General arguments about the importance of secondary depth cues in ecological viewing are developed.

Retinal image motion alone does not control disconjugate postsaccadic eye drift.

Abstract: 1. In these experiments, postsaccadic ocular drift was induced by postsaccadic motion of the visual scene. In the most important case, the scene was moved in one eye but not the other. Six human subjects viewed the interior of a full-field hemisphere filled with a random-dot pattern. During training, eye movements were recorded by the electrooculogram. A computer detected the end of every saccade and immediately moved the pattern horizontally in the same or, in different experiments, in the opposite direction as the saccade. The pattern motion was exponential with an amplitude of 25% of the size of the antecedent saccade and a time constant of 50 ms. Before and after 3-4 h of such training, movements of both eyes were measured simultaneously by the eye coil-magnetic field method while subjects looked between stationary targets for calibration, explored the visual pattern with saccades, or made saccades in the dark to measure the effects of adaptation on postsaccadic ocular drift. The amplitude of this drift was expressed as a percentage of the size of the antecedent saccade. 2. In monocular experiments, subjects viewed the random-dot pattern with one eye. The other eye was patched. With two subjects, the pattern drifted backward in the direction opposite to the saccade; with the third, it drifted onward. The induced ocular drift was exponential, always in the direction to reduce retinal image motion, had zero latency, and persisted in the dark. After training, drift in the dark changed by 6.7% in agreement with our prior study with binocular vision, which produced a change of 6.0%. 3. In a dichoptic arrangement, one eye regarded the moveable random-dot pattern; the other, through mirrors, saw a different random-dot pattern (with similar spacing, contrast, and distance) that was stationary. These visual patterns were not fuseable and did not evoke subjective diplopia. In this case, the induced change in postsaccadic drift in the same three subjects was only 4.8%. In all cases the changes in postsaccadic drift were conjugate--they obeyed Hering's law. 4. Normal human saccades are characterized by essentially no postsaccadic drift in the abducting eye and a pronounced onward drift (approximately 4%) in the adducting eye. After training, this abduction-adduction asymmetry was preserved in the light and dark with monocular or dichoptic viewing, indicating again that all adaptive changes were conjugate. 5. When the subjects viewed the adapting stimulus after training, the zero-latency, postsaccadic drift always increased from levels in the dark.(ABSTRACT TRUNCATED AT 400 WORDS)

The early development of visual acuity in the binocular and monocular peripheral fields

Abstract: We used FPL to assess 1-, 2-, and 3-month-olds' visual acuity at 20° in the binocular and monocular peripheral fields. Acuities were very poor at 1 month under both binocular and monocular viewing conditions but improved steadily over the next 2 months. Three-month-olds showed better acuity for gratings located in the temporal than in the nasal visual field.

Effects of monocular occlusion on neural and motor response times for two-dimensional stimuli.

Abstract: Previous studies have shown that there are advantages associated with the simultaneous use of both eyes to view two-dimensional stimuli. To investigate further this binocular advantage, three experiments were conducted using male and female names presented on a video display as stimuli. In the first experiment, simple reaction times (RT's) were found to increase by about 6% as a result of monocular occlusion. In the second experiment, visual evoked response (VER) and P300 implicit times were also found to increase as a result of occlusion. The third experiment confirmed these results and investigated the sensitivity of evoked potential techniques to changes in stimulus complexity. The three experiments demonstrate that monocular occlusion does have a significant effect on processing speed for two-dimensional visual stimuli. The major portion of this effect (62%) is manifest at the level of the visual cortex, and is not perceived by subjects as significantly increasing the mental workload associated with generating responses to these stimuli.

Orientation-specific luminance aftereffects

Abstract: Prolonged viewing of bright vertical (horizontal) gratings alternating-with-dim horizontal (vertical) gratings generates negative brightness aftereffects that are contingent on the orientation of orthogonal test gratings. The effect is measured by a brightness cancellation technique, similar to the color cancellation technique used in measuring McCollough effects. Like the latter, brightness aftereffects appear to persist for long periods. The magnitude of these aftereffects is a positive monotonic function of the luminance difference between the inducing gratings, and it depends on the conditions of induction; monocular induction generates larger aftereffects than binocular induction does. The aftereffect transfers interocularly, although its mangitude in the contralateral eye is substantially attenuated; binocular measurement, following monocular induction, results in even smaller aftereffects. An attempt to understand these findings within the computational model of brightness perception developed by Grossberg and Mingolla (1985a, 1985b) is presented.

Age and binocular advantage: A VEP assessment.

Abstract: Monocular and binocular visual evoked potentials (VEP's) were recorded in response to contrast-reversing checkerboard patterns of 2 check sizes (14 and 28 min arc) and 2 contrast-reversal rates (1.88 and 7.50 rps) in children (10 and 11-year-olds) and young adults (20 to 30-year-olds). The magnitude of binocular advantage, expressed as the ratio of the binocular to the average monocular response, was assessed by amplitude measurements of the major positive peak. The overall VEP amplitudes were larger for children than for adults across all conditions. The VEP amplitudes for binocularly viewed patterns were also consistently larger than the VEP amplitudes for the monocularly viewed patterns for both age groups. However, when the binocular advantage was expressed as a ratio of binocular to monocular average (MAV), the amplitude difference between the age groups was no longer apparent; although the children's average VEP responses were of a larger amplitude, the binocular advantage remained the same regardless of age.

Localization of Autonomous Mobile Robots by Monocular Vision in Modelled Sites. Application to a Nuclear Power Plant.

Abstract: This paper presents all the procedures up to now integrated in the \"ULYSSE\" software and designed for the automatic localization of a mobile robot in the area of the airlock of an \"ELECTRICITE DE FRANCE\" nuclear power plant. It is shown that if the initial pose of the robot is known, if a 3D geometrical model (even partial) is available, if a coarse estimation of each displacement is provided from odiometric devices. then the pose of the robot can be automatically determined by monocular vision and by matching the successive images and the CAD model. This matching occurs between the linear edges of the model and the image straight contours obtained after a polygonal approximation, and the attitude of the model is derived from the interpretation of the projection of at least three model edges.