Stereoscopic Acuity and Horizontal Angular Distance from Fixation*

Rawlings, Samuel C.; Shipley, Thorne

doi:10.1364/josa.59.000991

Cited by 52 publications

(31 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarity in the HD encoding characteristics between foveal and parafoveal regions is surprising. Indeed, we could expect changes in the HD encoding at parafoveal eccentricities, such as lower percentage of selective cells and/or coarser tuning curves, since our ability to evaluate stereoscopic depth decreases quickly with increasing retinal eccentricity (McKee 1983;Rawlings and Shipley 1969).…”

Section: Discussionmentioning

confidence: 99%

Neurons in Parafoveal Areas V1 and V2 Encode Vertical and Horizontal Disparities

Durand

Zhu

Celebrini

et al. 2002

Journal of Neurophysiology

View full text Add to dashboard Cite

Trotter. Neurons in parafoveal areas V1 and V2 encode vertical and horizontal disparities. J Neurophysiol 88: 2874 -2879, 2002; 10.1152/jn.00291.2002. Stereoscopic vision mainly relies on binocular horizontal disparity (HD), and its cortical encoding is well established in the foveal representation of the visual field. The role of vertical disparity (VD) is more controversial. Thus far, in the monkey, very few studies have investigated the HD sensitivity beyond 5°of retinal eccentricity and no evidence of a real encoding of VD exists in the parafoveal representation of areas V1 and V2. Using dynamic random dot stereograms, we have tested both HD and VD selectivities in the parafoveal representation of V1 (calcarine V1) and V2 (eccentricities Ͼ 10°) in a behaving monkey. HD and VD selectivities have been characterized using fitting with Gabor function. A large proportion of the tested cells were both HD and VD selective (47%) and, to a lesser extent, HD selective only (8%) or VD selective only (23%). We found a real encoding of VD, with the same diversity in the tuning profiles as described for HD, that cannot be assimilated to a simple perturbation of the HD matching process. Moreover, the VD encoding had a finer scale than the HD one, which is coherent with the smaller range of naturally occurring VD. For the HD encoding, both the percentage of selective cells and the tuning parameters were close to those reported in foveal V1. These results show that, at parafoveal eccentricities in V1 and V2, disparity detectors are tuned to both horizontal and vertical dimensions of the positional disparity existing between matched features in both retinas. I N T R O D U C T I O NThe retinal disparity of a physical point in space corresponds to the difference in location between its left and right retinal projections. It can be quantified as the angular difference between the two monocular visual directions associated with this point. In this way, its horizontal disparity (HD) is the difference between its left and right monocular azimuths, and its vertical disparity (VD) is the difference between the monocular elevations (Ogle 1962). Because the eye separation is in the horizontal dimension, HD and VD do not contain the same kind of information about the three-dimensional (3D) world. The horizontal component of the binocular disparity carries information about relative distances between points in space. Stereoscopic vision mainly relies on the HD signal, which is sufficient to drive a stereoscopic perception of depth (Julesz 1960). However, HD also varies as a function of the position of the viewed object respective to the head. VD carries information that theoretically permits disambiguation of the HD signal, and several models have been proposed to explain how HD and VD could interact to recover the 3D space with or without an extraretinal source of information on the position of the eyes in their orbit (Gårding et al. 1995;Koenderink and van Doorn 1976;Mayhew and Longuet-Higgins 1982;Weinshall 1990). Psychophysical expe...

show abstract

Section: Discussionmentioning

confidence: 99%

Neurons in Parafoveal Areas V1 and V2 Encode Vertical and Horizontal Disparities

Durand

Zhu

Celebrini

et al. 2002

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…Depth perception becomes less sensitive for stimuli peripheral to where the observer is looking (McKee, 1983;Rawlings and Shipley, 1969). One study compared peripheral and central viewing of static stereopsis and motion-in-depth in strabismic patients and found selective preservation of peripheral motion-indepth in some individuals (Kitaoji and Toyama, 1987).…”

Section: Utility Of Cdot and Iovd Informationmentioning

confidence: 99%

Binocular vision and motion-in-depth

2008

View full text Add to dashboard Cite

When an object moves in three dimensions, the two eyes' views of the world deliver slightly different information to the visual system, providing binocular cues to depth and motion-in-depth. This short review describes the two main sources of binocular information, namely, changing disparity over time and interocular velocity differences; this could be used for the perception of motion-in-depth. We discuss the evidence obtained in recent years on the extent to which each of them is used in human vision. We also highlight outstanding questions and issues in the field that have yet to be addressed.

show abstract

“…Because the density of receptors on the retina is not constant, therefore, it is reasonable to assume that the magnitude of uncertainty about spatial position (standard deviation of noise) varies across the retina. More exactly, this uncertainty is approximately proportional to eccentricity (Anstis, 1974;Pizlo, Rosenfeld, & Epelboim, 1995;Rawlings & Shipley, 1969). But what is the coefficient of proportionality?…”

Section: Simulation Experimentsmentioning

confidence: 99%

Binocular shape constancy from novel views: The role of a priori constraints

Chan

Stevenson

et al. 2006

Perception & Psychophysics

View full text Add to dashboard Cite

Shape constancy refers to the fact that the percept of the shape of a given object remains constant despite changes in the shape of the retinal image. The retinal image may change because of changes in the orientation of the object, relative to the observer. Shape is usually defined by angles and by ratios of distances. According to this definition, rigid motions and size scaling do not change shape. In other words, shape is invariant under similarity transformations. A perspective transformation between the 3-D scene and the 2-D retina is quite different from a similarity transformation (Pizlo, Rosenfeld, & Weiss, 1997). First of all, it is a many-to-one mapping. As a result, the information about depth is lost, and the shape on the retina may change substantially when the orientation of the object, relative to the observer, changes. It follows that shape constancy is a difficult computational problem. In the case of familiar objects, shape constancy could, theoretically, be achieved by means of a simple template-matching mechanism, in which the current view is compared with all previously seen views of the object. In order to provide an adequate test between this and other mechanisms, one should use unfamiliar objects and test shape constancy from unfamiliar (novel) views. Rock and DiVita (1987) performed the first systematic study of shape constancy from novel views, using 3-D objects. They used unstructured 3-D wire objects, which were viewed binocularly from a close viewing distance. Rock and DiVita reported a complete failure of shape constancy in the presence of a difference of only 45º between the views of an object. The authors concluded that the shapes of 3-D objects are perceived (and recognized) by memorizing a large number of 2-D images taken from many different viewing directions-the template matching mentioned in the first paragraph. In a subsequent study, Rock, Wheeler, and Tudor (1989) provided additional evidence by showing that observers cannot imagine how a novel wire object looks from a new viewing direction. The results of these two studies strongly suggest that the perceptual representation of objects does not involve 3-D properties. Biederman and Gerhardstein (1993) reported a quite different result. They used line drawings of unfamiliar 3-D geometrical objects built from geons and demonstrated almost perfect shape constancy from novel views (geons are simple 3-D objects, such as a box, cone, cylinder, or pyramid; Biederman, 1987). This result is, actually, hardly surprising because, phenomenologically, it is easy to imagine how novel or familiar objects built from geons (and many other structured objects) look from new viewing directions. In other words, Biederman and Gerhardstein's study provided strong support for the claim We tested shape constancy from novel views in the case of binocular viewing, using a variety of stimuli, including polyhedra, polygonal lines, and points in 3-D. The results of the psychophysical experiments show that constraints such as planarity of surface contour...

show abstract

Stereoscopic Acuity and Horizontal Angular Distance from Fixation*

Cited by 52 publications

References 8 publications

Neurons in Parafoveal Areas V1 and V2 Encode Vertical and Horizontal Disparities

Neurons in Parafoveal Areas V1 and V2 Encode Vertical and Horizontal Disparities

Binocular vision and motion-in-depth

Binocular shape constancy from novel views: The role of a priori constraints

Contact Info

Product

Resources

About