Relative height = depth cue - objects at diff distances from the viewer on the ground plane will form images at diff
heights in retinal image. Objects further away will be seen as higher in the image
Multiple cues interact to produce a final perception, similar to the metaphor of perceptual committees
Familiar size = depth cue – based on knowledge of typical size of objects
Occlusion is a nonmetrical cue. Relative size and relative height cues, esp if taken together provides some metrical
info. Relative size and height can’t tell us the exact distance but they are relative metrical depth cues = depth cue
that could specify, that object A was twice as far away as B w/o providing info about the absolute distance to either
A or B. Familiar size can be absolute metrical depth cue = depth cue that provides absolute info about the distance
in the 3 dimension, if our visual system knew the actual size of the object and the visual angle of the object’s
projection on the retina, it then can calculate exact distance from object to eye, in theory but in practice, ur visual
system not know exact.
AERIAL/ LINEAR PERSPECTIVE
Aerial perspective (haze perspective) = depth cue based on the implicit understanding that light is scattered by
atmosphere. Thus, more distant objects are subject to more scatter and appear fainter, bluer and less distinct.
Linear perspective = depth cue based on the fact that lines that are parallel in 3D world will appear to converge in a
2D world, except when the parallel lines lie in a plane that is parallel to the plane of the 2D image for ex, a closed
door, the parallel edges will remain parallel but when we open the door, the base boards are not parallel. The board
will meet a vanishing point = apparent point at which parallel lines receding in depth converge. Linear perspective
provides relative metrical depth info and can be seen as a special case of relative size and height cues.
PICTORIAL DEPTH CUES AND PICTURES
Pictorial depth cues = cue to distance or depth used by artists to depict 3D depth in 2D pictures, these cues are the
ones described above.
Anamorphosis/ anamorphic projection = use of the rules of linear perspective to create a 2D image so distorted
that it looks correct only when viewed from a special angle or w/a mirror that counters the distortion
Motion parallax = 1st nonpictorial depth cue = cue based on head movement. Geometric info obtained from an eye
in 2 diff positions at 2 diff times (motion parallax) similar to the info from 2 eyes in diff positions in the head at
same time (stereopsis). Parallax refers to the geometric relationship: when your eyes move, objects closer to you shift
position more than objects farther away when you change your viewpoint. cue provides relative metrical info.
Downside of motion parallax is that it works only if the head moves, just moving the eyes back and forth not work.
ACCOMMODATION AND CONVERGENCE
Accommodation = process by which eye changes its focus (lenses gets fatter as gaze is directed toward near objects)
If we can monitor our state of accommodation and or extent to which our eyes were converged, we could use this
info as a cue to depth of the objects we were typing to bring into focus: the more we have to converge, the more lens
have to bulge, the closer it is. When we focus on objects more than 2-3m away, the lens is as thin as it can get and the