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Stereoscopic occlusion junctions


Portions of surfaces in a binocularly viewed scene may be 'half occluded', that is, visible in only one eye. The human visual system uses zones of half occlusion to help segment the visual scene and infer figure–ground relationships at object boundaries. We developed a quantitative model of the depth-discontinuity cue provided by half occlusion. Half occlusions are revealed by two-dimensional interocular displacements of binocularly viewed occlusion junctions, such as T junctions. We derived a formula relating this two-dimensional displacement, or 'pseudodisparity', to binocular disparities and orientations of occluding and occluded contours. In human psychophysical experiments, perceived depth and contour orientation quantitatively depended on pseudodisparity, as predicted by our model, implying that the visual system senses quantitative variations in interocular junction position to reconstruct occlusion geometry.

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Figure 1: A stereopair of a natural scene containing a large number of occlusion junctions.
Figure 2: Examples of stereoscopic half-occlusion junctions. For ease of fusion, the center column presents the left eye view and the side columns present the right eye view.
Figure 3: Geometrical abstraction of a stereoscopic occlusion junction.
Figure 4: Experimental results. Scatter plots of perceived orientation versus predicted orientation of subjective contours for two observers assessing disparity and orientation for the I-junction stimulus from Fig. 2c (see Methods).


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Correspondence to Jitendra Malik or Barton L. Anderson.

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Malik, J., Anderson, B. & Charowhas, C. Stereoscopic occlusion junctions. Nat Neurosci 2, 840–843 (1999).

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