Showing papers on "Monocular vision published in 1992"

Recognizing novel views of three-dimensional objects.

Abstract: The purpose of the experiments reported was to examine how novel, three-dimensional shapes are represented in long-term memory and how this might be differentially affected by monocular and binocular viewing. Three experiments were conducted. The first experiment established that slide projections of the novel objects could be recognized readily if seen in the same orientation as seen during learning. The second and third experiments examined generalization to novel depth rotations of the objects. The second experiment used slide projections of the objects. The results indicated that the representation of the objects seen during training was quite viewpoint-specific as recognition of objects in novel orientations was relatively poor. In the third experiment subjects were shown the real objects under monocular or binocular viewing. Overall, the results are consistent with a growing body of recent research showing that, at least under certain conditions, the visual system stores viewpoint-specific representations of objects.

Spatial judgements with monoscopic and stereoscopic presentation of perspective displays

Abstract: Spatial judgments with monoscopic and stereoscopic presentation of perspective displays were investigated in the present study. The stimulus configuration emulated a visual scene consisting of a volume of airspace above a ground reference plane. Two target symbols were situated at various positions in the space, and observers were instructed to identify the relative depth or altitude of the two symbols. Three viewing orientations (15, 45, or 90 deg elevation angle) were implemented in the perspective projection. In the monoscopic view, depth cues in size, brightness, occlusion, and linear perspective were provided in the format. In the stereoscopic view, binocular disparity was added along the line of sight from the center of projection to reinforce the relative depth in the visual scene. Results revealed that spatial judgments were affected by manipulation of the relative spatial positions of the two target symbols and by the interaction between relative position and viewing orientation. The addition of binocular disparity improved judgments of three-dimensional spatial relationships, and the enhancement was greater when monocular depth cues were less effective and/or ambiguous in recovering the three-dimensional spatial characteristics.

Learning to See Random-Dot Stereograms:

Abstract: In the present study some specific properties of the learning effects reported for random-dot stereograms are examined. In experiment 1 the retinal position-specific learning effect was reproduced and in a follow-up experiment it was shown that the position specificity of learning can be accounted for by selective visual attention. In experiments 2 and 3 evidence was obtained that suggests that observers can learn, to a certain degree, monocular random-dot patterns and that this learning facilitates the depth percept. This result indicates that the traditional belief that random-dot stereograms are devoid of monocularly recognizable or useful forms should be reconsidered. In the second set of experiments the learning of two binocular surface properties of random-dot stereograms, depth edges and internal depth regions, was investigated. It was shown in experiment 4 that the depth edges of random-dot stereograms are not learned, whereas the results of experiment 5 indicate that the internal depth regions are learned. Finally, in experiment 6 it was shown that depth edges are learned when the internal depth regions of the stereogram are ambiguous. The results are discussed in terms of the importance of the particular type of stimulus used in the learning process and in terms of perceptual learning and attention.

On the variety of percepts associated with dichoptic viewing of dissimilar monocular stimuli.

Abstract: Upon dichoptic viewing of dissimilar patterns, several distinct perceptual states may be experienced over time. One state is exclusive monocular dominance, wherein the view of only one eye is seen in its entirety for some period of time. Another state is characterized by a mosaic-like college consisting of portions of the view of each eye. Two other states involve simultaneous perception of both monocular images in their entirety. In one of these states, the two monocular stimuli appear to be superimposed without depth (a phenomenon we shall term 'superimposition'). In the other state, the two monocular stimuli appear to be located at different depth planes (which we shall term 'transparency'). This paper documents the stimulus conditions favoring these various perceptual states. Exclusive monocular dominance occurs most often when the two eyes view dissimilar patterns with the same spatial-frequency content, particularly when both patterns consist of low spatial frequencies. Superimposition also occurs most often when the two eyes view the same spatial frequencies, but predominantly when those spatial frequencies are high. Transparency is favored when the spatial-frequency difference between the eyes is great, particularly when the view of one eye consists of high spatial-frequency information.

Model-based visual feedback control for a hand-eye coordinated robotic system

Abstract: The integration of a single camera into a robotic system to control the relative position and orientation between the robot's end-effector and a moving part in real time is discussed. Only monocular vision techniques are considered because of current limitations in the speed of computer vision analysis. The approach uses geometric models of both the part and the camera, as well as the extracted image features, to generate the appropriate robot control signals for tracking. Part and camera models are also used during the teaching stage to predict important image features that appear during task completion. >

The acquisition of catching under monocular and binocular conditions.

Abstract: The effects of binocular and monocular viewing on spatial and temporal errors in one-handed catching were investigated in two experiments. The first experiment—using expert catchers—recorded more spatial errors under the monocular than under the binocular condition. No significant differences in the number of temporal errors were apparent. In a second experiment, which used a transfer paradigm, relatively poor catchers were trained under both vision conditions. Its objective was to investigate whether the superior results obtained under the binocular condition in the first experiment, for the number of catches and number of spatial errors, could be attributed simply to the fact that subjects had more experience with binocular than monocular viewing. The following results occurred after a period of training: (a) a significant reduction in the number of spatial errors under the monocular condition, reaching a level similar to that under the binocular condition; (b) no significant reduction in the n...

Obstacle Detection, Tracking And State Estimation For Autonomous Road Vehicle Guidance

Abstract: An integrated spatio-temporal approach to real-time monocular vision in combination with a &dimensional fast symmetry analysis is presented for obstacle recognition and relative state estimation This module is one pard of Q system for autonomous vehicle guidance Obstacles ie other vehicles are detected and tracked up to a distance of 100 meters The system is able to handle multiple objects The number is limited by hardware resources

Neon flank and illusory contour: interaction between the two processes leads to color filling-in.

Abstract: Two aspects of neon color spreading, local color spreading (neon flank) and illusory contour, were investigated by dichoptic viewing. Neon flank was not observed under appropriate dichoptic stimulation, suggesting that input to the process for local color spreading is based on monocular configuration. However, illusory contours were formed according to the interocularly combined configuration rather than according to each monocular configuration, suggesting that input to the process responsible for illusory contours should be ocularly-nonselective and binocular, rather than monocular. The possibilities of artifacts such as those arising from interocular rivalry were appropriately eliminated, and thus, it is tentatively concluded that the process underlying local color spreading is monocularly driven, whereas the process underlying illusory contours is binocularly driven. Furthermore, a new demonstration is presented that indicates that interocularly-induced illusory contours ‘capture’ and extend the monoc...

The role of binocular information in ball catching.

Abstract: The role of binocular vision in a ball-catching task involving spatial uncertainty was examined in three experiments In all three experiments, subjects' catching performance was evaluated during monocular and binocular viewing, in normal room lighting and in complete darkness with a luminescent ball Subjects' performance was found to be significantly better with binocular than with monocular vision, especially under normal lighting conditions In the second and third experiments, catching performance was evaluated in the presence of minimal visual frames, consisting of a series of light-emitting diodes (LEDs) In Experiment 2, the visual frame consisted of a single plane of LEDs, whereas in Experiment 3, the visual frame consisted of two planes of LEDs Catching performance was found to be significantly better with the visual frame than in complete darkness, but this was true only for binocular viewing This result supports the hypothesis that binocular convergence is used to scale perceived space and that this information enables subjects to contact the ball successfully It was further found that postural sway varied between lighting conditions and that less sway was accompanied by higher performance There was no effect of binocular viewing in this respect In general, the results suggest two additive effects of viewing conditions: a direct effect of binocular vision on ball catching and an indirect effect of lighting on postural stability, which, in turn, affects catching performance

Vertical disparity and binocular vision in the praying mantis.

Abstract: We have investigated how the binocular control of prey capture in the praying mantis is affected by abnormally large vertical disparities, which were introduced by prisms placed in front of the eyes. The position of a target on the two retinae determines both the magnitude of head saccades made to fixate a target and its perceived distance. Over the whole range of vertical disparities tested (up to at least 30 deg), the frequency of fixating saccades is normal while the amplitude of their vertical component is a compromise between the saccades specified by each eye individually. Distance measurements are not affected by imposed vertical disparities. But the larger the vertical disparity, the more reluctant the mantid is to strike at the target until disparities exceed 15 deg when no strikes are elicited at all.

Correlations of memory and learning with vision in aged patients before and after a cataract operation.

Abstract: The connection between memory and learning with vision was investigated by studying 100 cataract operation patients, aged 71 to 76 years, 25 of them being men and 75 women. The cataract operation restored sufficient acuity of vision for reading (minimum E-test value 0.40) to 79% of the subjects. Short-term memory was studied with series of numbers, homogenic and heterogenic inhibition, and long sentences. Learning was tested with paired-associate learning and word learning. Psychological symptoms were measured on the Brief Psychiatric Rating Scale and personality on the Mini-Mult MMPI. Memory and learning improved significantly when vision was normalized after the cataract operation. Poor memory and learning scores correlated with monocular vision before the operation and with defects in the field of vision, due to glaucoma and exceeding 20%, postsurgery. Monocular vision and defects in the visual field caused a continuous sense of abnormalness, which impaired old people's ability to concentrate on tasks ...

Functional binocular vision is not dependent on visual experience in the praying mantis.

Abstract: In vertebrates, it has been shown that binocular visual experience is necessary to develop normal spatial vision. We have investigated whether this is also true for an invertebrate, the praying mantis. The praying mantis is a predatory insect in which prey localization involves the use of binocular disparities. We raised mantids which had one eye occluded throughout development and tested monocular visual fixation and binocular distance estimation in the adult animals. The results revealed that both fixation and prey catching behavior were normally functional in the monocularly reared animals. Thus we conclude that, in mantids, binocular vision is based on a fixed mode of development.

Stereolatency: a stereopsis test for everyday depth perception.

Abstract: An instrument is described which tests for the use of stereopsis by measuring how long it takes for depth perception to begin (its latency) after a transition from monocular to binocular vision. Starting at 1 s, the duration of binocular vision is reduced progressively toward a limit of 16 ms (or increased to a limit of 4 s) until the latency of stereopsis is found. The preliminary period of monocular vision acts as a probe for suppression of either eye and allows time for accommodation and vergence to stabilize before binocular vision begins. Typical results are presented.

Monocular vernier acuity in normally binocular, monocular, and amblyopic subjects.

Abstract: Previous experiments that have compared monocular vernier acuity in amblyopic, monocularly blind, and normal binocular subjects have been confined to the center of the retina. Based on brain changes that accompany the early disruption of form vision in one eye, monocularly blind subjects (that is, those who have completely lost the ability to process form vision in one eye) and amblyopic subjects are expected to have better vernier acuity in their normally functioning eye than subjects with normal binocular vision. Results from such studies have been ambiguous. This experiment was set up to study monocular vernier acuity in the central and peripheral retina of the three groups of subjects mentioned above. The results show that, at the center, monocularly blind subjects have the best vernier acuity followed by the amblyopic subjects and, finally, the normal binocular subjects have the worst acuity. In the peripheral retina, no significant differences were found between the three groups. A possible explanation has been provided for this finding.

Monocular acuity in the presence and absence of fusion

Abstract: Because little is known about monocular acuity during binocular fusion, acuity of the right eye was measured in binocularly normal subjects, with the fellow eye open or fully occluded. The target was flashed for 65 ms or presented sinusoidally for 1 s. Subjects had both eyes optimally focused, or the right eye defocused by +3.00 D. Monocular acuities were equivalent during fusion or occlusion when both eyes were optimally focused. Acuity of the defocused eye was reduced when the fellow eye was open compared to when it was occluded. Suppression of the blur, therefore, produced a measurable reduction in recognition thresholds. As monocular acuity was not measurably affected by the fellow eye when each eye was in focus, the finding that monocular vision is improved with the fellow eye occluded should be ascribed to something other than suppression or more sensitive spatial measures of the suppression should be obtained.

Mobility of normal observers under conditions of reduced visual input.

Abstract: The importance in mobility performance of the rate of presentation of visual information, binocular versus monocular vision, the use of multiple rather than single reference points, and local motion parallax was investigated in two experiments. In each experiment ten subjects walked a triangular mobility course in a totally darkened room; the only visible targets were light emitting diodes (LEDs), mounted on poles, at the apices of the triangle. The LEDs were mounted so that one or two could be used in a trial; if two were used the distance between them was varied horizontally (in experiment 1) and vertically (in experiment 2). The subjects walked around the course under a range of conditions, including two ‘optimal trials’ in full light. The LEDs were flashed for 1 ms at frequencies of 0.5, 1 and 5 Hz in experiment 1 and at 1 and 5 Hz in experiment 2. Mobility was measured with the use of an ultrasonic locator system which measured the subject's position on the course 10 times per second.The mean velocit...

Binocular vision system

Abstract: PURPOSE:To form a monocular vision image against an object by giving phases to a right and left images inputted from a right and left image pickup cameras on the basis of the brightness of each picture element of each image and making interference so that the object to which the three-dimensional depths contained in the two images are equal to each other. CONSTITUTION:This binocular vision system is provided with a left and right image pickup cameras for taking the left and right images 1 and 2 of a three- dimensional object, three computing elements (1)3, (2)4, and (3)5 which calculate the segmentation of the object, frame memories (1)6 and (2)7 for storing calculated results, and a frame memory (3)8 which stores picture data of complex type initial values required for the segmentation of the three-dimensional object and calculated results. Such an interference process that can extract an object having a three-dimensional depth at the same focal point from the two picture data to which phases are given on the basis of the brightness of each picture element of each image is performed on the images 1 and 2 taken by the cameras and the object is segmented in real time. Therefore, a monocular vision image can be formed to the object.

Depth reversal in binocular vision with symmetrical convergence

Abstract: Binocular vision is the coordinated behavior of the two eyes by which a single perception of the external world is obtained and by which, the specific sensation of stereoscopic depth perception, is made possible. This perception, however, can be reversed by interchanging the left- and right-eye views. In this paper, the mathematical expression of the Vieth-Mueller circle is derived. A point on the line of the primary direction is found which only relates to the convergence angle and the interocular distance. A relation is developed between the position of a point in real space and its reversal if viewed pseudoscopically. It is shown that in some circumstances a concave surface is not necessarily perceived as a convex surface under pseudoscopic viewing conditions. The difference in perceiving real objects and stereograms is briefly discussed.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Adaptive control techniques for dynamic visual repositioning of hand-eye robotic systems

Abstract: Using active monocular vision for 3-D visual control tasks is difficult since the translational and the rotational degrees of freedom are strongly coupled. The paper addresses several issues in 3-D visual control and presents adaptive control schemes for the problem of robotic visual servoing (eye-in-hand configuration) around a static rigid target. The objective is to move the image projections of several feature points of the static rigid target to some desired image positions. The inverse perspective transformation is assumed partially unknown. The adaptive controllers compensate for the servoing errors, the partially unknown camera parameters, and the computational delays which are introduced by the time-consuming vision algorithms. The authors present a stability analysis along with a study of the conditions that the feature points must satisfy in order for the problem to be solvable. Finally, several experimental results are presented to verify the validity and the efficacy of the proposed algorithms. >

Monocular pose estimation of quadrics of revolution

Abstract: The ability to determine an object's position accurately and quickly is important in many robotics tasks.Monocular scene analysis based on perspective projection can be successfully used to solve this problem if a-priori knowledge on objects is available. In this paper analytic procedures for perspective inversion of quadrics of revolution — in particular for spheres, cones and cylinders — are presented. Preliminary experimental results on real images of a test object are provided, with the main goal to test the procedures accuracy and the suitability of the available low-level processing. 1 INTRODUCTION Monocular computer vision is one of the most challenging approaches for 3D scene analysis. The basicidea of monocular vision is to understand in which situations and under which conditions a single 2D imagecan provide enough information for a 3D interpretation of the scene. A set of paradigms, known as "shape from X" , has been developed within this reference, such as shape from shading, shape from texture and shapefrom contours.Among the methodologies of monocular computer vision, perspective inversion as a tool to infer 3Dinformation from 2D data plays a very important role, especially for its consolidated mathematical foundationsand for its large applicability [4,5,7,2,6,8]. Independently of the kind of application, the basic problem ofperspective inversion is to recover the 3D orientation of some scene elements, referred to as primitives, startingfrom their 2D projection in the image plane, exploiting model knowledge to get the necessary constraints.Within industrial robotics, applications like object recognition and manipulation are good examples ofsituations in which a lot of information (often in the form of CAD models) is available both on the objectsand on the environment structure. Anyway, at present other new applications are emerging that seem as wellsuitable for the perspective inversion approach, like the auto-positioning and the landmark-based navigationof autonomous mobile robots.This paper presents some mathematical procedures which allow to compute the perspective inversion ofquadnics of revolution, obtaining completely analytic solutions.