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Showing papers on "Monocular vision published in 1997"


Journal ArticleDOI
TL;DR: It is argued that the presented theory can provide a unified account of a variety of monocular and binocular illusions that induce uniform transformations in perceived lightness, including neon-color spreading, the Munker – White illusion, Benary's illusion, and illusory monocularand binocular transparency.
Abstract: A theory of illusory transparency and lightness is described for monocular and binocular images containing X-, T- and I-contour junctions. This theory asserts that the geometric and luminance relationships of contour junctions induce illusory transparency and lightness percepts by causing a phenomenal scission of a homogenous luminance into multiple contributions. Specifically, it is argued that a discontinuous change in contrast along aligned contours that preserve contrast polarity induces a scission of the lower contrast region into a near-transparent surface or an illumination change, and a more distant surface that continues behind this near layer. This scission is assumed to cause changes in perceived lightness and/or surface opacity. Discontinuous changes in contrast along contours also are assumed to induce end-cut illusory contours that run roughly perpendicular to the inducing orientation of the contour, both monocularly and binocularly. Binocular illusory contours are shown to be caused by the ...

284 citations


Journal ArticleDOI
TL;DR: In this article, the role played by binocular vision in the execution of prehension movements was examined in three experiments which examined transport and grasp kinematics for prehensions executed under binocular, monocular, and no vision (memory-guided and open-loop) viewing conditions.
Abstract: Vision is critical for the efficient execution of prehension movements, providing information about: The location of a target object with respect to the viewer; its spatial relationship to other objects; as well as intrinsic properties of the object such as its size and orientation. This paper reports three experiments which examined the role played by binocular vision in the execution of prehension movements. Specifically, transport and grasp kinematics were examined for prehension movements executed under binocular, monocular, and no vision (memory-guided and open-loop) viewing conditions. The results demonstrated an overall advantage for reaches executed under binocular vision; movement duration and the length of the deceleration phase were longer, and movement velocity reduced, when movements were executed with monocular vision. Furthermore, the results indicated that binocular vision is particularly important during “selective” reaching, that is reaching for target objects which are accompanied by fl...

103 citations


Journal ArticleDOI
TL;DR: It was found that irrespective of the presence of environmental structure, an effect of ball size occurred in the monocular viewing conditions, while in the binocular viewing condition subjects behaved in accordance with a constant time to contact strategy: no effects ofBall size were found.

101 citations


Journal ArticleDOI
TL;DR: Fear of cyclotorsion should not be a deterrent to considering macular translocation as a possible treatment option for severe subretinal macular hemorrhage if the patient is willing to accept monocular vision.
Abstract: • Purpose: To document the functional outcome of two patients following successful macular translocation for the treatment of severe subretinal hemorrhage in age-related maculopathy. • Methods: The retina was surgically rotated around the optic nerve with translocation of the fovea either upward or downward to an area of healthy retinal pigment epithelium. In the postoperative period, visual function was carefully studied with emphasis on adaptation to torsion. • Results: Visual acuity in one patient improved from 2/200 to 20/80 and the other patient remained at 20/200. Both patients developed horizontal and vertical strabismus with torsion of up to 55°. After a prolonged period of occlusion of the unoperated eye, both patients were subjectively able to adapt to monocular torsion. However, adaptation under binocular conditions did not occur. • Conclusion: Macular translocation was successful in improving visual acuity in one patient, with no improvement in the second. Both patients had significant ocular torsion and strabismus, but under monocular conditions they were successful in perceptually adapting to the change in the visual environment. Fear of cyclotorsion should not be a deterrent to considering macular translocation as a possible treatment option for severe subretinal macular hemorrhage if the patient is willing to accept monocular vision.

52 citations


Journal ArticleDOI
TL;DR: Perceived directions of monocular objects cannot be specified by geometrical rules that include only the positions of the objects and of the two eyes, so perceived directions ofmonocular objects are captured by the binocular visual directions of adjacent binocular objects.

50 citations


Journal ArticleDOI
TL;DR: It is suggested that capture of binocular visual direction results from a mechanism of lateral interaction between adjacent visual directions that ensures that, despite eye movements, objects have the same spatial order in monocular and binocular vision.

43 citations


Journal ArticleDOI
TL;DR: It is suggested that the dominant eye is in a tonic state and plays the primary role in far-to-near accommodation in binocular viewing and shortening of the response time and an increase in the response velocity are noted.

39 citations


Journal ArticleDOI
TL;DR: The results of the 1st and 2nd experiments indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy and that central vision of the hand seemed to be used for on-line directional control of relatively slow movements.
Abstract: The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55°/s) than those usually used in studies that had proved its existence (over 110°/s) was determined. The results indicated that this visual kinetic channel was operative even at relatively slow movement velo...

37 citations


Journal ArticleDOI
TL;DR: This work measured contrast letter acuity in normally sighted binocular control subjects and compared these results to previously published results of eye enucleated subjects and monocular viewing control subjects, finding equivalent performance between enucleation subjects and binocularcontrol subjects, suggesting that performance of en nucleated subjects might be due to some form of neural summation.

21 citations


Journal ArticleDOI
TL;DR: The amplitude enhancement of binocular VEPs, which mainly occurs when using small checks, may be related to the increase in the total amount of cortical activity representing the macular region; this may account for binocular superiority in fine spatial resolution.
Abstract: Monocular and binocular visual evoked potentials (VEPs) in response to different check sizes (15-21-38-84 minutes of arc) were studied in 14 subjects with normal visual acuity and stereopsis. The binocular VEP amplitude is slightly higher than the VEP amplitude on stimulation of the “better eye” and significantly higher than the VEP amplitude on stimulation of the “worse eye”; this effect is observed using small checks and almost exclusively involves N75-P100. Both the N75 and P100 peaks occur earlier after binocular than monocular stimulation. The shortening of the N75 mean latency is significantly greater than that of the P100 mean latency when larger check sizes are used. The mean latency of the N145 potential is not significantly different in monocular and binocular stimulus conditions. The slight summation effect and latency shortening in the binocular VEPs are not consistent with the hypothesis that it is the sum of separate monocular signals originating from the visual cortex that gives rise to the response. The early components of both monocular and binocular VEPs are thought to be of post-synaptic origin (outside layer 4c of area 17), where the imputs become mixed so that most cells receive information from both eyes. The amplitude enhancement of binocular VEPs, which mainly occurs when using small checks, may be related to the increase in the total amount of cortical activity representing the macular region; this may account for binocular superiority in fine spatial resolution. The latency shortening in binocular conditions can be explained by considering that the critical determinant of the latency is the fundamental spatial frequency of the pattern. When coarse patterns are used, their effectiveness in parafoveal stimulation may affect the VEPs, with a significant contribution coming from the more peripheral retina. The enlargement of the visual field when the eyes see simultaneously may therefore further reduce the latency of the response when using the larger checks suitable for eccentric stimulation.

20 citations


Journal ArticleDOI
TL;DR: A method to localize a cylindral surface with only one perspective view is presented and two axes in the image are found in order to obtain the three rotation angles between the cylindrical surface coordinate system and the camera coordinate system.

Journal ArticleDOI
TL;DR: Objective measurement of fixation disparity with the direct method is quicker and more reliable than with the monocular occlusion method.
Abstract: Purpose Previous studies have measured objective fixation disparity using a monocular occlusion method, by which the monocular components of misalignment are revealed by measuring the shift in the position of the fixating eye after occlusion of the other eye. Methods We assessed the use of the monocular occlusion method by comparing it to direct measurements of binocular vergence. Results The direct method required precise calibration, but was found to be reliable. Several problems were discovered with the monocular occlusion method: (1) when using a central fusion stimulus, fixation was difficult to control accurately enough to measure the small monocular shifts in eye position expected at lower vergence demands; (2) with a peripheral fusion target, objective fixation disparity could not be measured directly; and (3) upon occlusion, a variable saccade occurred in the fixating eye. Conclusion Objective measurement of fixation disparity with the direct method is quicker and more reliable than with the monocular occlusion method.

Journal ArticleDOI
TL;DR: Investigation on the Random‐Dot E (ROE) stereotest under binocular and monocular non‐stereoscopic viewing conditions concluded that caution should be used when interpreting results from the RDE stereotests, since adult observers could discern some differences between the test plates monocularly.

Journal ArticleDOI
TL;DR: All blood investigations, including erythrocyte sedimentation rate, full blood count and immunoglobulin screen, were normal and Gastric parietal cell antibodies were present at a titre of 1:80 but no other autoantibodies were detected.
Abstract: A woman aged 48 attended the eye casualty with a 24-hour history of painless loss of vision in her right eye. She had had regular attacks of ocular migraine affecting her right eye since the age of 14. These had always begun with a central bright area with tiny sparks zigzagging across her vision. This became dark and spread within minutes to involve the entire field of vision in the right eye. Each attack lasted for up to one hour but always resolved spontaneously. She had stopped smoking after a myocardial infarction 2 years previously but had resumed after the death of her husband eight months ago. Her regular prescribed medication was aspirin 300 mg, atenolol 100 mg and frusemide 40 mg daily. On examination her Snellen visual acuity was hand movements in the right eye and 6/5 in the left eye with full refractive correction. There was an afferent pupillary defect in the right eye. The ocular media were clear and the intra-ocular pressure was normal and equal in the two eyes. Fundus examination revealed a cherry-red spot at the right macula (Figure 1) and a normal retinal appearance in the left eye. No embolus could be seen anywhere in the arteriolar tree on fluorescein angiography (Figure 2) although arteriolar filling was abnormally delayed to 13s (normal

Journal ArticleDOI
TL;DR: Thresholds for (generic) nonrigid transformations that in theory can be detected from rigid ones by processing pairs of views depended not only on the extent to which the rigidity constraints were affected, but also on the structure and the movement of the simulated object.
Abstract: Wemeasured thresholds for the monocular discrimination of rigidly and nonrigidly moving objects defined by motion parallax. The retinal projections of rigidly moving objects are subject to certain constraints. By applying smooth 2-D transformations to the projections of rigidly moving objects, we created stimuli in which these constraints were affected. Thresholds for (generic) nonrigid transformations that in theory can be detected from rigid ones by processing pairs of views depended not only on the extent to which the rigidity constraints were affected, but also on the structure and the movement of the simulated object. Nonrigid transformations under which every three successive views had a rigid interpretation were not discriminable from rigid transformations, except in cases where the distortions were very large. Under the rigidity assumption, this would mean that a large class of nonrigidly moving objects is erroneously perceived as rigidly moving.

Journal ArticleDOI
TL;DR: The slower and asymmetrical monocular learning of experimental cats may reflect a conflict and a competition between the hemispheres for the control of learning behaviour, resulting in the dominance of one of them.

Journal ArticleDOI
TL;DR: This study describes a method of tracking of human body limbs from a monocular sequence of perspective images based on the interpretation of image features as the three-dimensional perspective projections points of the object model and an iterative process method to compute the model position in accordance with the analysed image.

Proceedings Article
10 Sep 1997
TL;DR: This system introduces a scheme that uses only one camera (together with a mirror) to derive the 3D coordinates of a target object and allows the user to use his/her bare fingers to point to any position in the3D space.
Abstract: Speed, robustness, and cost are three important factors that determine the success of a vision-based human-computer interaction system. In our system, we introduce a scheme that uses only one camera (together with a mirror) to derive the 3D coordinates of a target object. To ensure a more natural interaction between the human and the computer, our system allows the user to use his/her bare fingers to point to any position in the 3D space. In addition, robustness and speed is achieved through the use of the chain-code algorithm. The accuracy of the results is improved through the use of suitable post-processing filters. The performance of our system is thoroughly evaluated.

Book ChapterDOI
08 Oct 1997
TL;DR: The designed neural network tracking system performs smooth pursuit of slow objects (50°) with a foveal error less than 0.7° and is able to track objects up to a maximum speed of 320° with foveals less than 4.5°.
Abstract: The neural control system of a high speed monocular camera head for the tracking of real-world targets is presented in this paper. The tracking system consists of four subsystems: monocular camera head. adaptive image processing system for estimation of the momentary position of object, neural network predictor and PID-controller, controlling motors of the camera head. The designed neural network tracking system performs smooth pursuit of slow objects (50°) with a foveal error less than 0.7° and is able to track objects up to a maximum speed of 320° with foveal error less than 4.5°.

Book ChapterDOI
10 Sep 1997
TL;DR: In this paper, a system that uses only one camera and a mirror to derive the 3D coordinates of a target object is presented, and the accuracy of the results is improved through the use of suitable post-processing filters.
Abstract: Speed, robustness, and cost are three important factors that determine the success of a vision-based human-computer interaction system. In our system, we introduce a scheme that uses only one camera (together with a mirror) to derive the 3D coordinates of a target object. To ensure a more natural interaction between the human and the computer, our system allows the user to use his/her bare fingers to point to any position in the 3D space. In addition, robustness and speed is achieved through the use of the chain-code algorithm. The accuracy of the results is improved through the use of suitable post-processing filters. The performance of our system is thoroughly evaluated.

Proceedings ArticleDOI
TL;DR: It can be said that this HMD has the possibility of being well suited to human vision in terms of the convergence, and it was found that the convergent state of the monocular vision was nearly equal to that of binocular vision.
Abstract: A compact and wide field of view HMD having 1.32-in full color VGA poly-Si TFT LCDs and simple eyepieces much like LEEP optics has been developed. The total field of view is 80 deg with a 40 deg overlap in its central area. Each optical unit which includes an LCD and eyepiece is 46 mm in diameter and 42 mm in length. The total number of pixels is equivalent to (864 times 3) times 480. This HMD realizes its wide field of view and compact size by having a narrower binocular area (overlap area) than that of commercialized HMDs. For this reason, it is expected that the frequency of monocular vision will be more than that of commercialized HMDs and human natural vision. Therefore, we researched the convergent state of eyes while observing the monocular areas of this HMD by employing an EOG and considered the suitability of this HMD to human vision. As a result, it was found that the convergent state of the monocular vision was nearly equal to that of binocular vision. That is, it can be said that this HMD has the possibility of being well suited to human vision in terms of the convergence.