Toward a new theory of stereopsis.

Abstract

Humans can obtain an unambiguous perception of depth and 3-dimensionality with one eye or when viewing a pictorial image of a 3-dimensional scene. However, the perception of depth when viewing a real scene with both eyes is qualitatively different: there is a vivid impression of tangible solid form and immersive negative space. This perceptual phenomenon, referred to as "stereopsis", has been among the central puzzles of perception since the time of da Vinci. After Wheatstone's invention of the stereoscope in 1838, stereopsis has conventionally been explained as a by-product of binocular vision or visual parallax. However, this explanation is challenged by the observation that the impression of stereopsis can be induced in single pictures under monocular viewing. Here I propose an alternative hypothesis that stereopsis is a qualitative visual experience related to the perception of egocentric spatial scale. Specifically, the primary phenomenal characteristic of stereopsis (the impression of 'real' separation in depth) is proposed to be linked to the precision with which egocentrically scaled depth (absolute depth) is derived. Since conscious awareness of this precision could help guide the planning of motor action, the hypothesis provides a functional account for the important phenomenal characteristic associated with stereopsis: the impression of interactability. By linking stereopsis to a generic perceptual attribute, rather than a specific cue, it provides a potentially more unified account of the variation of stereopsis in real scenes and pictures, and a basis for understanding why we can perceive depth in pictures despite conflicting visual signals. StereopsisVishwanath 3

The Effects of Changing Projection Geometry on Perception of 3D Objects on and Around Tabletops

“…Although our experiment was not explicitly designed with the purpose of solving this controversy from the perception literature, it does provide support for previous research which found that the exclusive geometrical approach to perception does not account correctly for the perception data (e.g., [Koenderink et al, 1993;Perkinks, 1973;Goldstein, 1991;Ellis et al, 1991]). Similarly, it provides support for more current accounts of perception, in which cue conflicts are posited to be the cause of degraded perception [Vishwanath, 2014].…”

“…Binocular rendering of 3D content for collaborative environments is currently economically and computationally expensive; moreover, binocular rendering does come with added problems due to conflicting depth cues (e.g., accommodation and binocular disparity will result in different estimations of depth [Vishwanath, 2014]). Nevertheless, future development of display technologies and systems that enable binocular observation of 3D scenes is plausible.…”

Quality, quantity and precision of depth perception in stereoscopic displays

“…These results show that increasing apparent depth does not necessarily increase the quality of the 3D experience. Rather, as predicted by theoretical considerations [6,17,18,19], depth quality, or stereopsis, was more closely related to the precision than to the magnitude of perceived depth. Our results are consistent with the idea that the qualitative experience of stereopsis is associated with the precise representation of depth information [6,18,19].…”

“…However, it has also been proposed that stereopsis is associated with the reliability and precision of perceived depth [6,17], particularly with egocentrically scaled metric depth [18,19]. The purpose of the current study was to provide empirical data to test between these theoretical ideas.…”

“…This striking improvement in appearance is related to the concept of 'stereopsis'. Literally meaning 'solid sight', this term refers to the vivid impression of solidity and depth that is perceived in S3D, but is lacking in non-stereoscopic displays [18]. This experience of the realness and solidity of depth is a component of the assessment of quality in S3D [10,13].…”