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Depth perception Barton L. Anderson, MIT

Summary: Depth perception
Barton L. Anderson, MIT
One of our most remarkable perceptual capacities is our ability to recover the three
dimensional structure of our environments. All of our actions rely on the ability to recover
information about the positions, shapes, and material properties of objects and surfaces as they
exist in three-dimensional space. In vision, depth perception refers to the ability to recover depth
from the two dimensional images projected to our two eyes. The information used to recover
depth can be divided into two broad kinds: information contained in a single view of a scene
(pictorial depth); and information contained in multiple views (the sense of depth generated by
either motion and/or our two eyes [stereopsis]).
Many pictorial depth cues are a consequence of what happens when the 3D world is
projected onto the backs of our eyes. As distance from an observer increases, parallel lines on a
ground plane appear to converge (also known as linear perspective); texture becomes
increasingly compressed and more dense along the line of sight, creating texture gradients; and
contrast decreases from atmospheric haze, commonly referred to as aerial perspective. For
example, when a circular disc is tilted away from the observer, it projects the image of an ellipse.
The aspect ratio of the ellipse depends on the degree of tilt relative to the observer's line of gaze,
and the size of the ellipse depends on both object size and viewing distance. If a series of circles
are placed on the ground and viewed from an angle, the circles will project a series of ellipses
that become smaller and "flatter" as distance from the observer increases, producing a texture


Source: Anderson, Barton L. - School of Psychology, University of Sydney


Collections: Biology and Medicine