Binocular Stereopsis Research Articles

A34 Research on 3D data Acquisition and Configuration of Live Images(M4 processes and micro-manufacturing for science)

Most of applications are based on two dimensional images. Recently, there are increasing demands of 3D information for new applications. The aim of research is to develop an algorithm for acquisition and configuration of 3D profile by means of binocular stereopsis. In previous research, we have developed the algorithm of acquisition and configuration of 3D data for static image. In this reserach, the 3D data acquisition and configuration are performed on live stereo vision. In the case of live stereo vision, improvement in processing speed is implemented to accommodate to the commercial motion capture systems in the video rate.

Comprehensive vision care in urban communities: The pediatric outreach program

Background The Illinois College of Optometry's (ICO) Pediatric Outreach Program (POP) provides comprehensive vision care for high-risk children from birth to approximately 5 years of age in partnership with early intervention programs throughout the city of Chicago. Grant funds assisted in the ability to deliver vision services and spectacles to uninsured children. This report describes the structure and organization of the POP and presents the visual data. Methods Comprehensive eye examinations were performed on 4,298 children ages birth to approximately 5 years at 76 early intervention program sites. All of the children evaluated were enrolled from early intervention/Head Start programs. Visual acuity determination (by Lea method), assessment of binocular status, stereopsis evaluation, cycloplegic retinoscopy, and ocular health evaluations were performed. As necessary, eyeglasses were prescribed. Amblyogenic risk factors, strabismus, and ocular pathology were identified. Results Of the 4,298 children examined, 49% were boys and 51% were girls. Two percent were younger than 12 months old, 6% were 1.1 to 2 years old, 12% were 2.1 to 3 years, 30% were 3.1 to 4 years, 35% were 4.1 to 5 years, 14% were 5.1 to 6 years, and 1% were older than 6 years. Hyperopia and emmetropia were the most common refractive classifications among the children examined. Approximately 6.5% had risk factors for isometropic amblyopia, and 2.3% had risk factors for anisometropic amblyopia. Approximately 1% of the children had strabismus. Less than 1% of the children examined were identified with ocular pathology. Spectacles were dispensed to 16.6% of the children examined. Conclusions The Pediatric Outreach Program provides early identification and treatment of abnormal visual conditions, ensuring that children have maximal visual acuity and visual function. The educational aspects of the program have also contributed to its successes. Education for parents and early intervention agency staff promote the importance of comprehensive vision examinations for children 5 years of age and younger.

Stereo saliency map considering affective factors and selective motion analysis in a dynamic environment

We propose new integrated saliency map and selective motion analysis models partly inspired by a biological visual attention mechanism. The proposed models consider not only binocular stereopsis to identify a final attention area so that the system focuses on the closer area as in human binocular vision, based on the single eye alignment hypothesis, but also both the static and dynamic features of an input scene. Moreover, the proposed saliency map model includes an affective computing process that skips an unwanted area and pays attention to a desired area, which reflects the human preference and refusal in subsequent visual search processes. In addition, we show the effectiveness of considering the symmetry feature determined by a neural network and an independent component analysis (ICA) filter which are helpful to construct an object preferable attention model. Also, we propose a selective motion analysis model by integrating the proposed saliency map with a neural network for motion analysis. The neural network for motion analysis responds selectively to rotation, expansion, contraction and planar motion of the optical flow in a selected area. Experiments show that the proposed model can generate plausible scan paths and selective motion analysis results for natural input scenes.

A neural model for stereo transparency with the population of the disparity energy models

The disparity energy model can interpret a variety of physiological properties of binocular neurons in the early visual cortex quantitatively. Therefore, many physiologically plausible models for binocular stereopsis employed the disparity energy model as a model neuron. These models can explain a variety of psychological findings concerning stereo perception. However, most of the models cannot handle with stereo transparency. Here, we develop a simple stereo model for transparency perception with the hybrid-type disparity energy model, and examine the ability to detect overlapping disparities. Computer simulations showed that the model properties of transparency detection are consistent with many psychophysical findings concerning stereo transparency.

Automatic 3D shape recovery for rapid prototyping

The capacity to create, display and manipulate a three-dimensional (3D) computer model and produce a physical replica of an existing object, enabling 3D re-shaping activities, plays an important role in different areas such as engineering, biology, architecture and archaeology. Some improvements have been made in a biologically based computer-aided design system, called BioCAD, specifically designed for the rapid and accurate 3D shape recovery from existing large objects, creating 3D computer models either to produce sophisticated photo-realistic renderings, two-dimensional drawings, or to generate surface models for simulation purposes and rapid prototyping applications. This improved system comprises three main routines through which the major findings are as follows: i) the algorithm for “ciliary” calibration routine enables to converge all digital image sequence, so uncertainties decrease, resulting in higher accuracy; ii) through the binocular stereopsis routine, the 3D shape of the perceived large object can actually be inferred; iii) STL and SLI routine allows to integrate BioCAD system and other advanced computer-aided technologies, enabling one to obtain a very small layer thickness from a straightforward slicing process of STL files with a large dimension, minimising the slicing processing time by exploring the advantage of the Matlab language, in terms of matrix manipulation and RAM memory of personal computers.

Immediate vs delayed sequential cataract surgery: a comparative study

Immediate sequential cataract surgery (ISCS) is still a controversial procedure. We compared the clinical and patient-reported outcomes of ISCS vs the usual delayed sequential cataract surgery (DSCS). Selected patients with bilateral cataracts were assigned nonrandomly and according to their preferences to either ISCS in one session (intervention group) or DSCS over two sessions with a 2-month interval between sessions (control group). Binocular visual acuity, binocular contrast sensitivity, stereopsis, and self-reported visual function (VF-14) were measured preoperatively and postoperatively for up to 4 months after the second-eye surgery. Mann-Whitney U-test was used to compare quantitative variables, while the chi(2) and Fisher's exact tests were used for qualitative variables. Of the 220 eligible patients, 74 (33.6%) chose ISCS, and 137 (62.3%) selected DSCS. The remaining patients (4.1%) were allocated randomly to either group. For 2 months, the outcome measures were significantly worse in the DSCS group than in the ISCS group. However, after 4 months (2 and 4 months after second-eye surgery in the DSCS and ISCS groups, respectively) the differences became insignificant except for VF-14 (P<0.05). The mean post-operative objective measures and their differences from baseline were not significantly different between the groups. Nevertheless, postoperatively, VF-14 improved more (P<0.05) and attained a higher value (P<0.05) in the ISCS group. In experienced hands, with stringent patient selection criteria and with a strict aseptic protocol, ISCS can safely provide a more rapid rehabilitation of VF than DSCS.

The role of binocular stereopsis in monoptic depth perception

In his study of depth from monocular elements, Kaye (1978) [Kaye, M. (1978). Stereopsis without binocular correlation. Vision Research, 18(8), 1013–1022] reported that monocular stimuli, briefly presented to one eye in a stereoscopic display, generated reliable depth percepts. Here we replicate and extend Kaye’s findings in an effort to identify the mechanism underlying the phenomenon. Our experiments show that the perception of depth is not a simple result of monocular local sign, for the percept of depth disappears when one eye is patched. In subsequent experiments we assess the possibility that the percept results from a very coarse stereoscopic match to either the centroid of the luminance distribution in the unstimulated eye or a simple match to the line of sight in the unstimulated eye. Our results consistently support the match-to-fovea account, and lead us to conclude that monoptic depth is a stereoscopic phenomenon.

Critical Immaturities Limiting Infant Binocular Stereopsis

To determine what critical immaturity is responsible for the poor binocular stereopsis of human infants. Infant and adult psychometric functions were measured for detection of stereoscopic depth in a random-texture display. A test stimulus defined by horizontal binocular disparity and a distracter stimulus defined by vertical disparity were used. Adults were tested by direct psychophysical methods at several contrast values, and infants by forced-choice preferential looking at 100% contrast. Infant stereoacuity matured from unmeasurable at age 12 weeks to 7.9 arc min at 20 weeks, which was still far from the nominal adult value of 5 to 10 arc seconds. In contrast, infant d-max (maximum disparity) was 86.8 minutes at 20 weeks, which was near the adult d-max of 110.6 minutes. The average maximum level of infant performance at 20 weeks was 77% correct, still far below adult performance. When the adult stereogram was low contrast, adult extrafoveal performance was similar to infant performance. Infant and adult stereo performance was predicted quantitatively, using infant and adult monocular performance in detecting the stereogram texture. Infant and adult stereopsis performance approached, but did not reach, the predicted values. The infantlike performance of adults tested at low contrast and the similarity of infant maximum percentage of correct data relative to the predicted values suggested that the critical immaturity limiting infant stereopsis is the well-known insensitivity of the infant visual system to contrast. This conclusion supports the clinical use of stereopsis as a screening test for bilateral monocular function in infants.

An exploration of modified monovision with diffractive bifocal contact lenses

A group of eight presbyopic subjects wore in succession four types of correction. One of these (A) consisted of a conventional pair of diffractive bifocals in which equal amounts of light contributed to the distance and near images in both eyes. Two (B and C) were modified monovision corrections using non-standard diffractive bifocal lenses. The diffractive designs were such that in the dominant eye a greater fraction of light was sent into the distance image and less into the near image and in the non-dominant eye a greater fraction contributed to the near image. The last lens combination (D) was a conventional monovision arrangement, with a single-vision distance correction on the dominant eye and a single-vision near correction on the non-dominant eye. Monocular and binocular high-contrast acuity, contrast sensitivity and stereopsis were assessed at both distance and near with each of the four lens combinations. It was hoped that the modified monovision arrangements (B and C) might yield improved distance and near acuities in comparison with the standard diffractive bifocals (A) while still maintaining good stereopsis in comparison with the single-vision monovision combination (D) and thus allow wearers to achieve better all round visual performance. Although these expectations were at least partly fulfilled, the modest advantages offered by the diffractive modified monovision approach did not appear to compensate for the disadvantages of its greater complexity.

A statistical model of binocular disparity

Binocular disparity provides important information about the three-dimensional structure of the environment. The current study sought to complement our geometrical understanding of binocular vision by considering the distributions of horizontal and vertical disparities that might be expected in images of the natural environment, using a simple environmental model. It was observed that the distribution of disparities depends critically on fixation, and varies greatly from one image location to another. The results were considered in relation to computational models of binocular stereopsis, and compared to two known properties of the visual system—the small disparity preference in disparity matching, and the influence of eccentricity on Panum's fusional limit. Overall, the study characterizes the binocular disparities that are likely to be encountered in the real world scenes, and discusses the implications of these for our understanding of binocular visual systems.

305 ステレオ法によるSEM画像からの3次元計測および形状復元(精密/微細加工と評価)

305 ステレオ法によるSEM画像からの3次元計測および形状復元(精密/微細加工と評価)

Stereo and motion parallax cues in human 3D vision: Can they vanish without a trace?

In an immersive virtual reality environment, subjects fail to notice when a scene expands or contracts around them, despite correct and consistent information from binocular stereopsis and motion parallax, resulting in gross failures of size constancy (A. Glennerster, L. Tcheang, S. J. Gilson, A. W. Fitzgibbon, & A. J. Parker, 2006). We determined whether the integration of stereopsis/motion parallax cues with texture-based cues could be modified through feedback. Subjects compared the size of two objects, each visible when the room was of a different size. As the subject walked, the room expanded or contracted, although subjects failed to notice any change. Subjects were given feedback about the accuracy of their size judgments, where the "correct" size setting was defined either by texture-based cues or (in a separate experiment) by stereo/motion parallax cues. Because of feedback, observers were able to adjust responses such that fewer errors were made. For texture-based feedback, the pattern of responses was consistent with observers weighting texture cues more heavily. However, for stereo/motion parallax feedback, performance in many conditions became worse such that, paradoxically, biases moved away from the point reinforced by the feedback. This can be explained by assuming that subjects remap the relationship between stereo/motion parallax cues and perceived size or that they develop strategies to change their criterion for a size match on different trials. In either case, subjects appear not to have direct access to stereo/motion parallax cues.

Binocular Coordination of the Eyes during Reading

Saccadic eye movements and fixations are the behavioral means by which we visually sample text during reading. Human oculomotor control is governed by a complex neurophysiological system involving the brain stem, superior colliculus, and several cortical areas. A very widely held belief among researchers investigating primate vision is that the oculomotor system serves to orient the visual axes of both eyes to fixate the same target point in space. It is argued that such precise positioning of the eyes is necessary to place images on corresponding retinal locations, such that on each fixation a single, nondiplopic, visual representation is perceived. Vision works actively through a continual sampling process involving saccades and fixations. Here we report that during normal reading, the eyes do not always fixate the same letter within a word. We also demonstrate that saccadic targeting is yoked and based on a unified cyclopean percept of a whole word since it is unaffected if different word parts are delivered exclusively to each eye via a dichoptic presentation technique. These two findings together suggest that the visual signal from each eye is fused at a very early stage in the visual pathway, even when the fixation disparity is greater than one character (0.29 deg), and that saccade metrics for each eye are computed on the basis of that fused signal.

In a randomized controlled trial, cataract surgery in both eyes increased benefits compared to surgery in one eye only

Background and Objective Despite recommendation of surgery in both eyes in patients with bilateral cataract, there is little evidence about the benefits of second-eye surgery. The objective of this study was to compare the benefits of cataract surgery in both eyes with those of surgery in one eye only. Study Design and Setting Two-arm randomized controlled trial involving 296 patients with bilateral cataracts of two public teaching hospitals. Patients were randomly assigned to receive surgery in one eye only (control group) or surgery in both eyes, one eye at a time (intervention group). The main outcome measures were binocular visual acuity, binocular contrast sensitivity, stereopsis, and patient-reported visual disability (VF-14), measured 4–6 months postoperatively. Results A total of 135 (91.2%) and 139 (93.9%) patients completed the trial in the control and intervention groups, respectively. Postoperatively, intervention group presented a better visual acuity (difference of 0.07; 95% CI = 0.03, 0.12), stereopsis (0.62 log sec arc; 95% CI = 0.45, 0.79), and VF-14 (8.2 points; 95% CI = 4.4, 12.4). No significant differences were found for contrast sensitivity. Conclusions Bilateral cataract patients should have surgery in both eyes. Including stereopsis and patient-reported visual disability in the assessment of cataract patients, especially after first-eye surgery, will improve the evaluation of effectiveness.

Subpixel motion computing architecture

A pipelined optical-flow processing system that works as a virtual motion sensor has been described. It is based on a field programmable gate array (FPGA) device enabling the easy change of configuring parameters to adapt the sensor to different speeds, light conditions and other environmental factors. It is referred to as a 'virtual sensor' because it consists of a conven- tional camera as front-end supported by an FPGA processing device, which embeds the frame grabber, optical-flow algorithm implementation, output module and some configuration and storage circuitry. This is the first fully stand-alone working optical-flow processing system to include both accuracy and speed of measurement of the platform performance. The customisability of the system for different hardware resources and platforms has also been discussed, showing the resources and performance for a stand-alone board and a PCI co-processing board. Optical flow computation consists in extracting a dense velocity field from an image sequence assuming that inten- sity is conserved during displacement. This result may then be used for other applications such as 3-D reconstruction, time interpolation of image sequences, video compression, segmentation from motion, tracking, robot navigation, time-to-collision estimation and so on. The technical problem with estimating the motion of objects in 3-D is that, in the image formation process, because of the perspec- tive projection of the 3-D world onto the 2-D image plane, some of the information is lost. There are several ways of recovering the 3-D information from 2-D images using various cues. These cues are motion, binocular stereopsis, texture, shading and contour. In this paper, we will describe the implementation of a real-time motion flow system, leaving the potential applications for future studies. Optical-flow algorithms have been widely described in the literature. Some authors have addressed a comparative study of the accuracy of different approaches with synthetic sequences (1). Their evaluation using real-life sequences is difficult to address because the real optical flow of such sequences is unknown. We have focused on a classical gradient model based on Lucas and Kanade's (L & K) approach (1, 2). Several authors have emphasised the satis- factory trade-off between accuracy and efficiency in this model, which is an important factor when deciding which model is most suitable to use as a real-time processing system. For a comparative study (1), the L & K algorithm provides very accurate results, added to which, other authors specifically evaluating the efficiency against accu- racy trade-off of different optical-flow approaches (3) also regard the L&K model as being quite efficient. Finally,

Gelingt eine prismatische Korrektion des kleinwinkligen Einwärtsschielens mit der Mess- und Korrektionsmethodik nach Hans-Joachim Haase?

The "Measuring and Correcting Methodology after H.-J. Haase" is based on the assumption that a minute deviation from the orthovergence position (fixation disparity) indicates a difficulty to overcome a larger "vergence angle of rest". Objective recordings have, however, revealed that the subjective tests applied in the "Measuring and Correcting Methodology after H.-J. Haase" can mislead to the assumption of a fixation disparity, although both eyes are aligned exactly to the fixation point. How do patients with an inconspicuously small, yet objectively verified strabismus react to the "Measuring and Correcting Methodology by H.-J. Haase"? Eight patients with a microesotropia between 0.5 and 3 degrees were subjected to the "Measuring and Correcting Methodology after H.-J. Haase. In all 8 patients, the prisms determined with the Cross-, Pointer- and Rectangle Tests increased the angle of squint, without reaching a full correction: the original angle prevailed. In the Stereobalance Test, prisms did not reduce the 100 % preponderance of the non-squinting eye. The stereoscopic threshold was between 36 and 1170 arcsec in 7 out of the 8 subjects, and above 4000 arcsec in 1 subject. (1) In all 8 patients, prisms determined with the "Measuring and Correcting Methodology by H.-J. Haase" increased the angle of strabismus, without reaching bifoveal vision. This uniform result suggests that primary microesotropia cannot be corrected with the "Measuring and Correcting Methodology after H.-J. Haase" (2) A lacking contribution of the strabismic eye to the recognition of a lateral offset between stereo objects, as determined with the Stereobalance Test, does not imply a lack of binocular stereopsis.

The Interaction between Binocular Rivalry and Negative Afterimages

Afterimage formation, historically attributed to retinal mechanisms, may also involve postretinal process. Consistent with this notion are results from experiments, reported here, investigating the interaction between binocular rivalry and negative afterimages (AIs). In Experiment 1, one eye was exposed to a grating never consciously experienced by the observer because this grating remained suppressed in rivalry throughout induction (the exclusively dominant stimulus was designed to preclude formation of an AI). As expected, the suppressed grating generated a vivid AI whose orientation could be accurately identified; not surprisingly, the strength of this AI varied with induction contrast. Experiment 2 revealed, however, that the strength of this AI produced during suppression was significantly weaker than the AI produced by that same stimulus when it was visible throughout the entire induction period, implying that some component of AI induction is susceptible to interocular suppression. In Experiment 3, AIs of dichoptic, orthogonally oriented gratings were induced in a way ensuring that one of the two gratings was exclusively dominant during the induction period. Dissimilar monocular AIs engaged in rivalry, as expected, but, surprisingly, the AI induced by the suppressed grating initially dominated. We offer two alternative accounts of this counterintuitive finding, both based on differential neural adaptation.

A new look at binocular stereopsis

We report a new phenomenon, which illustrates that the role of binocular disparity in 3D shape perception critically depends on whether the parts are interpreted as belonging to a single object. The nature of this phenomenon was studied in four experiments. In the first two experiments the subjects were shown a sequence of stereoscopic images of a cube, in which binocular disparity indicated that the individual parts move towards or away from one eye. However, when the parts of the cube were perceived as elements of a single object, they appeared to move in a rigid fashion and the direction of motion was orthogonal to that predicted by the binocular disparities. The third experiment generalized these results to more complex polyhedra. The last experiment showed that constraints related to motion, such as rigidity, are important, but not critical for this phenomenon to occur. All these results imply that the interpretation as to what corresponds to a single object affects the importance (weight) of binocular disparity and may even eliminate its contribution altogether; the percept of a 3D shape is dominated by a priori constraints, and depth cues play a secondary role.

立体内視鏡下手術操作時の疲労に対する両眼立体視の影響

For medical stereoscopic imaging, the usefulness of the presentation of depth information and the issues of picture quality and fatigue have been discussed. The aim of this study is to investigate the influence of binocular stereopsis on surgeon's fatigue by subjective and psychophysiological scores.14 subjests were asked to perform three kinds of tasks-a pegboard, incision, and suturing-under the 2D and 3D conditions conducted for one hour in total. We evaluated the degree of fatigue by a questionnaire (Subjective Symptom Test of Fatigue) and by the critical flicker fusion frequency (CFF) test. In the flicker test, eyestrain due to the tasks was not observed under either 2D or 3D display conditions. Although subjective fatigues of muscles and eyes were significant, no difference was found depending on the display conditions. CFF did not show any evidence of fatigue caused by the binocular stereopsis.

Three-dimensional X-ray Imaging for Security Screening

The X-ray screening of luggage by aviation security personnel may be badly hindered by the lack of visual cues to depth in an image that has been produced by transmitted radiation. The standard procedures in use today employ two-dimensional ‘shadowgraphs’, with ‘organic’ and ‘metallic’ objects encoded using two different colours (usually orange and blue). In the context of luggage-screening there are no reliable cues to depth present in individual shadowgraph X-ray images. Therefore, the screener is required to convert the ‘zero depth resolution’ shadowgraph into a three-dimensional mental picture to be able to interpret the relative spatial relationship of the objects under inspection. Consequently, additional cognitive processing is required, eg integration, inference and memory. However, these processes can lead to serious misinterpretations of the actual physical structure being examined. This paper describes the development of a stereoscopic imaging technique which enables the screener to utilise binocular stereopsis to enhance interpretation of the actual nature of the objects under examination.