Brain can find depth and distance {depth perception} {distance perception} in scenes, paintings, and photographs.
depth: closeness
Closer objects have higher edge contrast, more edge sharpness, position nearer scene bottom, larger size, overlap on top, and transparency. Higher edge contrast is most important. More edge sharpness is next most important. Position nearer scene bottom is more important for known eye-level. Transparency is least important. Nearer objects are redder.
depth: farness
Farther objects have smaller retinal size; are closer to horizon (if below horizon, they are higher than nearer objects); have lower contrast; are hazier, blurrier, and fuzzier with less texture details; and are bluer or greener. Nearer objects overlap farther objects and cast shadows on farther objects.
binocular depth cue: convergence
Focusing on near objects causes extraocular muscles to turn eyeballs toward each other, and kinesthesia sends this feedback to vision system. More tightening and stretching means nearer. Objects farther than ten meters cause no muscle tightening or stretching, so convergence information is useful only for distances less than ten meters.
binocular depth cue: shadow stereopsis
For far objects, with very small retinal disparity, shadows can still have perceptibly different angles {shadow stereopsis} [Puerta, 1989], so larger angle differences are nearer, and smaller differences are farther.
binocular depth cue: stereopsis
If eye visual fields overlap, the two scenes differ by a linear displacement, due to different sight-line angles. For a visual feature, displacement is the triangle base, which has angles at each end between the displacement line and sight-line, allowing triangulation to find distance. At farther distances, displacement is smaller and angle differences from 90 degrees are smaller, so distance information is imprecise.
binocular depth cue: inference
Inference includes objects at edges of retinal overlap in stereo views.
monocular depth cue: aerial perspective
Higher scene contrast means nearer, and lower contrast means farther. Bluer means farther, and redder means nearer.
monocular depth cue: accommodation
Focusing on near objects causes ciliary muscles to tighten to increase lens curvature, and kinesthesia sends this feedback to vision system. More tightening and stretching means nearer. Objects farther than two meters cause no muscle tightening or stretching, so accommodation information is useful only for distances less than two meters.
monocular depth cue: blur
More blur means farther, and less blur means nearer.
monocular depth cue: color saturation
Bluer objects are farther, and redder objects are nearer.
monocular depth cue: color temperature
Bluer objects are farther, and redder objects are nearer.
monocular depth cue: contrast
Higher scene contrast means nearer, and lower contrast means farther. Edge contrast, edge sharpness, overlap, and transparency depend on contrast.
monocular depth cue: familiarity
People can have previous experience with objects and their size, so larger retinal size is closer, and smaller retinal size is farther.
monocular depth cue: fuzziness
Fuzzier objects are farther, and clearer objects are nearer.
monocular depth cue: haziness
Hazier objects are farther, and clearer objects are nearer.
monocular depth cue: height above and below horizon
Objects closer to horizon are farther, and objects farther from horizon are nearer. If object is below horizon, higher objects are farther, and lower objects are nearer. If object is above horizon, lower objects are farther, and higher objects are nearer.
monocular depth cue: kinetic depth perception
Objects becoming larger are moving closer, and objects becoming smaller are moving away {kinetic depth perception}. Kinetic depth perception is the basis for judging time to collision.
monocular depth cue: lighting
Light and shade have contours. Light is typically above objects. Light typically falls on nearer objects.
monocular depth cue: motion parallax
While looking at an object, if observer moves, other objects moving backwards are nearer than object, and other objects moving forwards are farther than object. For the farther objects, objects moving faster are nearer, and objects moving slower are farther. For the nearer objects, objects moving faster are nearer, and objects moving slower are farther. Some birds use head bobbing to induce motion parallax. Squirrels move orthogonally to objects. While observer moves while looking straight ahead, objects moving backwards faster are closer, and objects moving backwards slower are farther.
monocular depth cue: occlusion
Objects that overlap other objects {interposition} are nearer, and objects behind other objects are farther {pictorial depth cue}. Objects with occluding contours are farther.
monocular depth cue: peripheral vision
At the visual periphery, parallel lines curve, like the effect of a fish eye lens, framing the visual field.
monocular depth cue: perspective
By linear perspective, parallel lines converge, so, for same object, smaller size means farther distance.
monocular depth cue: relative movement
If objects physically move at same speed, objects moving slower are farther, and objects moving faster are nearer, to a stationary observer.
monocular depth cue: relative size
If two objects have the same shape and are judged to be the same, object with larger retinal size is closer.
monocular depth cue: retinal size
If observer has previous experience with object size, object retinal size allows calculating distance.
monocular depth cue: shading
Light and shade have contours. Shadows are typically below objects. Shade typically falls on farther objects.
monocular depth cue: texture gradient
Senses can detect gradients by difference ratios. Less fuzzy and larger surface-texture sizes and shapes are nearer, and more fuzzy and smaller are farther. Bluer and hazier surface texture is farther, and redder and less hazy surface texture is closer.
properties: precision
Depth-calculation accuracy and precision are low.
properties: rotation
Fixed object appears to revolve around eye if observer moves.
factors: darkness
In the dark, objects appear closer.
processes: learning
People learn depth perception and can lose depth-perception abilities.
processes: coordinates
Binocular depth perception requires only ground plane and eye point to establish coordinate system. Perhaps, sensations aid depth perception by building geometric images [Poggio and Poggio, 1984].
processes: two-and-one-half dimensions
ON-center-neuron, OFF-center-neuron, and orientation-column intensities build two-dimensional line arrays, then two-and-one-half-dimensional contour arrays, and then three-dimensional surfaces and texture arrays [Marr, 1982].
processes: three dimensions
Brain derives three-dimensional images from two-dimensional ones by assigning convexity and concavity to lines and vertices and making convexities and concavities consistent.
processes: triangulation model
Animals continually track distances and directions to distinctive landmarks.
Consciousness>Consciousness>Sense>Vision>Physiology>Depth Perception
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Date Modified: 2022.0224