Depth Perception

Abstract

This chapter contains a review of information that we use to perceive the three‐dimensional structure of the visual world. To a limited extent for near viewing we can use nonvisual signals from the accommodative state of the lens or the state of convergence of the eyes. Visual information available to one eye included image blur arising from out‐of‐focus images; overlap between images of objects at different distances serves as a cue to relative depth. Shading and shadows provide a rich source of information about relative depth, although the sign of depth relations can be ambiguous. When we move past a stationary scene, the relative motion of images of objects at different distances indicates very small differences in depth. Image expansion of an approaching object indicates time to impact and the symmetry of image motion indicates whether the approaching object will hit us. Binocular information available when only both eyes are open includes differences between the images in the two eyes. These binocular disparities provide information about the distances of objects, and the inclination and curvature of surfaces. The chapter ends with a discussion of how different depth cues interact to produce a unified percept of the three‐dimensional structure of the world.

Iso-disparity Surfaces for General Stereo Configurations

“…In other words, the retinas acts as if they were flat! As far as we could tell, this seems to be a new result [11]. Given a typical abathical distance of 1m and an interoccular distance of 6.5cm, the normal of the plane would deviate 1.86 degrees outwards from the visual axis.…”

“…Under the assumption that the retina is spherical and that corresponding points are spread symmetrically around the fovea, the horopter becomes a circle known as the Vieth-Müller circle [17]. It has, however, been observed that the empirical horopter deviates from the theoretical horopter by what is known as the Hering-Hillebrand deviations [11]. The empirical horopter is always flatter than the Vieth-Müller circle.…”

The neural basis of depth perception from motion parallax

“…These include pictorial depth cues that are present in a single static image of a scene, such as occlusion, relative size, perspective, shading, texture gradients and blur [1,2]. Although such pictorial cues are valuable in interpreting three-dimensional scene structure, they generally do not provide precise quantitative information about depth.…”

Depth cues do not underlie attentional modulations of the Stroop effect

“…The displays in that study contained a monocular depth cue-occlusion (see Howard, 2002). One rectangle occluded a second rectangle, which occluded the background.…”