5. Steropsis and Depth Perception Flashcards Preview

OD2-BVOM > 5. Steropsis and Depth Perception > Flashcards

Flashcards in 5. Steropsis and Depth Perception Deck (48)
Loading flashcards...

what is depth perception based on

multiple cues, each of which can sitmulate depth perception by themselves


what is a depth cue

a feature of the ocular images which changes w/ object depth


how are depth cues categorized in

2 ways, based on the need for binocular vision (mono cues and binocular cues)
2. the type of depth judement the cues support (absolute vs relative)


what are monocular depth cues

1. visual angle cues
-known size, looming, perspective, texture gradients
2. contrast cues
-contrast, aerial perspective, overlay, shadows and shading
3. motion cues
-motion parallax, knetic depth effect


what does absolute depth tell the observer
how are they judged
what are they analogous to

tells the oberver how far objects are from themselves or form other objects
-judged in absolute units of distance
-analogous to egocentric direction


what are the absolute depth cues

1. known size
2. stereopsis based on both horizontal and vertical disparity
3. convergence registration


what information is required for visually guided motion

absolute depth info


what does relative depth tell the observer
what are they judged as
what are they analogous to

tells the observer about relative order and proportion in depth
-judged as % diff or as depth ratios
-analogous to oculocentric direction


what are relative depth cues

stereopsis when based only on horiz disparity
-all cues that aren't aboslute cues


how are all these depth cues put together for a single depth perception

1. each relative depth cue is first promoted to absolute depth
(oculocentric to egocentric)
2. absolute depth cues are averaged by weight (strength in environment)


why do we have so many depth cues



why does stero not equal awareness of convergence

convergence creates a separate depth cue called "convergence registration" or "convergence corollary discharge"
-stero creates depth even when the eyes are fixed


what is the main stimulus to stereo

horizontal relative disparity


a single absolute disparity doesn't stimulate stereopsis..what does



the approx formula for real depth shows that stero depth stimulus is proportional to...

1. the physical depth interval btwn compared objects
2. interpupillary dist
-larger pd=stero depth more easily
3. inverse square of viewing distance
-1/2 viewing dist, stero stimulus quadruples


what is the projected depth

horiz relative disparity ay also be created by artificial lateral displacement of the ocular images in diff directions


what are some projected depth methods

1. wheatstone and brewster steroscopes
2. vectograms and red/green anaglyphs
3. rapid alternating img projection
4. free fusion and autostereograms


what depth methods do 3D movies

projected depth methods


stereoscopes are a type of _____ that present stereo images

-devices that allow independent stimulation of each eye


what are vectograms and R/G anaglyphs

stereoscopes w/o lenses or mirrors


what are advantages to vectograms and R/G anaglyphs?

advantage: more natural viewing (no optics), physically compact

disadvantage: polarized vectograms must be replaced periodically bc the polaroid material decays
-red/gree anagylphs may induce rivalry and suppression


what are the advantages/disadvantages of free fusion

advantage: enables fusion of stero cards w/o stereoscope
-important VT skill

dis: diplopic images
-requires much more dissocation of acc from vergence, compared to stereoscopes


what is the principle of autostereograms

each eye's image is projected to it in a limited optical cone in physical space
-each cone contains a full image for one eye


what are the types of autosterograms

lenticular displays
parallax barrier displays


what are the advantages/dis of autostereograms

ad: allows stereoscope viewing w/o special glasses or stereoscope optics
disad: limited head position range in physical space


why is horizontal relative disparity only a relative depth cue

bc relative disparity alone is ambiguous about absolute depth


how does vision ocnvert horiz relative disparity into absolute depth

by promoting horiz relative disparity by way of known size, vertical disparity, and convergence registration


what is vertical disparity

stimulation of noncorresponding points in the vertical dimension of the retinas


what causes vertical disparity in normal viewing

vertical disparity is stimulated by near objects to the side of the head
-these objects are seen as taller by thte ey eon the same side as the objects
-the size difference causes vertical disparity


why is veritcal disparity visually useful to vision

it is monotonically related to absolute depth