depth perception homemade

Spatial vision vs. space perception

Spatial vision is 2D pattern analysis on the retina; space perception is 3D interpretation of distance, depth, and shape.

Distance (egocentric distance)

The distance from the observer to an object.

Depth (relative distance)

How far one object is in front of another object or surface.

Surface orientation

The “slant” (how much) and “tilt” (which direction) of a surface in space.

Shape and size

Intrinsic properties of 3D objects that stay constant despite changes in viewpoint.

Types of depth cues

Monocular vs. binocular, pictorial vs. motion, physiological (accommodation).

Accommodation

A monocular physiological cue where lens shape changes with object distance.

Binocular cues

Include convergence, stereopsis, and binocular disparity—each eye’s offset provides depth information.

Pictorial depth cues

2D image cues such as junctions, linear perspective, texture, shading, occlusion, relative height, and familiar size.

Motion cues

Depth information from motion: motion parallax, kinetic depth effect, relative motion, and dynamic occlusion.

Epstein (1965) familiar-size experiment

Showed perceived distance can be inferred from known object size—viewers judged coins’ distance using familiarity.

Geometry of relative size

The same retinal image size can correspond to large far or small near objects; the brain uses context to resolve this inverse problem.

Relative size cue

Larger retinal image → perceived as closer when context is constant.

Occlusion cue

When one object blocks another, the blocked object is perceived as farther away (T-junctions indicate occlusion).

Perceptual completion

The brain “fills in” missing contours to complete occluded shapes.

Texture gradient cues

Density, foreshortening, and element size changes convey surface slant and depth.

Shading and illumination

The brain assumes light-from-above; shadows and gradients create depth impressions.

Aerial (atmospheric) perspective

Distant objects appear hazier, lower in contrast, and less saturated due to light scattering.

Linear perspective

Parallel lines converge with distance; provides strong monocular depth information.

Perceptual constancy

Perception of objects remains stable for color, shape, and size despite changes in viewing conditions.

Shape constancy

An object’s perceived shape remains constant despite changes in retinal projection.

Color constancy

Surface colors are perceived as stable across lighting changes.

Size constancy

Perceived object size remains consistent when distance changes; depends on accurate depth cues.

Ames room illusion

A distorted room makes two people of equal size appear drastically different due to misleading monocular depth cues.

Müller-Lyer illusion

Lines with inward or outward fins appear different in length though identical—depth cues cause mis-scaling.

Perception vs. action question

Tests whether perceptual judgments and physical actions (grasping) are equally affected by size illusions.

Vishton et al. (2007) findings

Verbal size judgments were more affected by illusions than grip size; touching reduced the illusion’s impact.

Bruggeman et al. (2007) findings

Binocular viewing yields accurate size/distance perception; monocular viewing increases susceptibility to slant illusions.

Moon illusion

The moon appears larger on the horizon than at zenith due to depth and contextual cues.

Apparent-distance theory (moon illusion)

Horizon moon appears farther because of surrounding terrain cues; greater distance causes larger perceived size.

Angular-size-contrast theory (moon illusion)

Overhead moon looks smaller because it’s surrounded by vast empty sky; horizon moon flanked by structures appears larger.

Emmert’s Law

The perceived size of an afterimage increases with the perceived distance of the surface it’s projected onto.

Motion parallax

As we move, closer objects move faster across the retina than distant ones—provides a powerful depth cue.

Dynamic (kinetic) occlusion

Depth information from the deletion and accretion of contours as objects move relative to each other.

Structure-from-motion

Perceiving 3D form purely from motion patterns.

Biological motion

Recognizing human or animal movement from minimal motion cues (e.g., light-dot walkers).

Structure-from-shading

Inferring 3D shape from gradients of illu