5. Steropsis and Depth Perception Flashcards
(48 cards)
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
- visual angle cues
- known size, looming, perspective, texture gradients - contrast cues
- contrast, aerial perspective, overlay, shadows and shading - 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
- known size
- stereopsis based on both horizontal and vertical disparity
- 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
- each relative depth cue is first promoted to absolute depth
(oculocentric to egocentric) - absolute depth cues are averaged by weight (strength in environment)
why do we have so many depth cues
reliability
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
2
the approx formula for real depth shows that stero depth stimulus is proportional to…
- the physical depth interval btwn compared objects
- interpupillary dist
- larger pd=stero depth more easily - 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
- wheatstone and brewster steroscopes
- vectograms and red/green anaglyphs
- rapid alternating img projection
- free fusion and autostereograms
what depth methods do 3D movies
projected depth methods
stereoscopes are a type of _____ that present stereo images
haploscope
-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?
disadvantages?
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
