Abstract
We asked if regularities in the visual environment provide a basis for some unexplained phenomena in stereovision. Specifically, we asked whether the positions of corresponding retinal points—positions in the two eyes that when stimulated yield the same perceived direction—are adapted to regularities in the binocular disparities encountered in the everyday environment. The positions of objects in the world that stimulate corresponding points define the horopter. Stereopsis is most precise near the horopter, which is pitched top back above fixation and is curved somewhat convexly to the left and right of fixation. Does the horopter align with regularities in the 3D visual environment? To answer this, we built a mobile device that simultaneously measures binocular fixations and the 3D scene layout. Subjects performed everyday activities, like preparing a meal or walking through an environment, while we measured where they were looking (including how far away) and the 3D scene in front of them. From these data we reconstructed the images projected to the eyes, particularly the binocular disparities, as subjects performed these tasks. The data revealed a number of things. 1) Disparities encountered during everyday tasks have clear regularities, which vary across tasks. 2) The encountered disparities tend to be uncrossed above fixation and crossed below in agreement with the pitch of the vertical horopter. 3) The encountered disparities during some, but not all, tasks tend to be uncrossed to the left and right of fixation in agreement with the convexity of the horizontal horopter. Thus, despite varying patterns from one task to another, the disparity distributions we measured generally align with the positions of corresponding points, supporting the hypothesis that the regions of best stereovision are well adapted to the complex patterns of visual input experienced in everyday activities.
Meeting abstract presented at VSS 2013