Stereopsis: Important Papers

Vision Research, 1997

Stereoacuity experiments tested definitions of binocularly disparate spatial positions by perturbing the binocular correspondence of the two half-images. Dichoptic translations perturbed zero-order retinal positions; expansions perturbed first-order horizontal separations; rotations perturbed first-order orientations; and anisotropic expansions deformed first-order two-dimensional (2D) structure. Each transformation perturbed relative positions in the two half-images by more than 100 arcsec, but stereoacuity thresholds remained about 10 arcsec. Binocular disparity involves second-order 2D differential structure of the monocular half-images, specifying local surface shape. Stereoacuity is much better than nonstereo acuity, suggesting that monocular spatial signals are binocularly correlated. © 1997

2007

Binocular information about the structure of a scene is contained in the relative positions of corresponding points in the two views. If the eyes rotate, in order to fixate a different target, then the disparity at a given image location is likely to change. Quite different disparities can be produced at the same location, as the eyes move from one fixation-point to the next. The pointwise variability of the disparity map is problematic for biological visual systems, in which stereopsis is based on simple, short-range mechanisms.

Perception & psychophysics, 1999

Vision Research, 1995

Vision research, 1979

Perception of tilt in depth on the basis of spatial frequency difference between the two eyes was subjected to new tests to determine whether it could be explained by conventional binocular disparity mechanisms. When usual disparity cues are invalidated by rapidly changing displays and by using stimuli uncorrelated between the two eyes, perception of tilt remained for a great range of soatial freouencv differences. It is suggested that the mechanism involved may be more primitive .

Vision Research, 1990

AWraet-In comparison to lateral ~d~~~ of distance, stereoscopic judgments are not precise. Although stereoacuity thresholds for targets presented in the fixation plane can equal the beet thresholds for the monocukr hypemcuitka. i.e. 8 few set arc, the increment thresholds for disparity are substantiahy larger than the increment threshohis for lateral separation (width). We measured the minimum detectable change in the thmedimensional distance. separating two features, one presented in the fixation phme, and the other some distance in front of it, i.e. with a significant standing disparity between the two features. For briefly-presented targets (1 SO msec), the Weber fraction for disparity was 1040% over the range from 1 to 2Omin arc, while the Weber fraction for width was only 2-3% under comparabk conditions. The disparity thresholds were substantially improved for a longer duration target (1000 msec), but they were still a factor of two worm than the monocular width thresholds. in a related atgeriment, the vender acuity for a standard vernkr target was profoundly degraded by pairing the offset upper line presented to one eye with a disparate line in the other eye; the vernier threshold was elevated for disparities ranging from 3 to 30min arc. This tinding shows that the more precise monocular signals are actively suppreaaed in fused or partially-fused stereoscopic images.

Vision Research, 2005

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.

Vision Research, 1972

Attention Perception & Psychophysics, 1984

Vision Research, 1995

The pattern of retinal binocular disparities acquired by a fixating visual system depends on both the depth structure of the scene and the viewing geometry. This paper treats the problem of interpreting the disparity pattern in terms of scene structure without relying on estimates of fixation position from eye movement control and proprioception mechanisms. We propose a sequential decomposition of this interpretation process into disparity correction, which is used to compute three-dimensional structure up to a relief transformation, and disparity normalization, which is used to resolve the relief ambiguity to obtain metric structure. We point out that the disparity normalization stage can often be omitted, since relief transformations preserve important properties such as depth ordering and coplanarity. Based on this framework we analyse three previously proposed computational models of disparity processing; the Mayhew and Longuet-Higgins model, the deformation model and the polar angle disparity model. We show how these models are related, and argue that none of them can account satisfactorily for available psychophysical data. We therefore propose an alternative model, regional disparity correction. Using this model we derive predictions for a number of experiments based on vertical disparity manipulations, and compare them to available experimental data. The paper is concluded with a summary and a discussion of the possible architectures and mechanisms underling stereopsis in the human visual system.