cosc 6326/psych6750x vision and visual displays. why do we have two eyes? binocular vision has...
TRANSCRIPT
![Page 1: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/1.jpg)
Cosc 6326/Psych6750X
Vision and Visual Displays
![Page 2: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/2.jpg)
Why do we have two eyes?
• Binocular vision has several advantages including– increased field of view– redundancy– increased detection probability– depth perception from
• vergence
• stereopsis
![Page 3: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/3.jpg)
Geometry of Binocular Correspondence
• Images in the two eyes differ (or are disparate) due to separation of vantage points
• Points of light project to the same retinal locations in the two eyes only on the horopter
• Points off the horopter have horizontal and/or vertical disparity
![Page 4: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/4.jpg)
Vieth-Müller circle
Binocular subtense
Nodal points
F
P
O
F'F' P'P'
N1 N2
![Page 5: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/5.jpg)
The Geometrical Point Horopter
LE RE
Fixation PointUncrossed disparity
Crossed disparity
![Page 6: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/6.jpg)
Even flat frontal surfaces have disparity
• Differential perspective• Both horizontal and
vertical disparities• Gradient of vertical size
disparity– Varies with distance
– Affects depth, shape judgments …
Left Eye Image Right Eye Image
![Page 7: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/7.jpg)
Vergence
![Page 8: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/8.jpg)
Vergence eye movements
• opposite (disjunctive) movements of the eyes
• a principle function is to align both high acuity foveae on target of interest
• vergence helps bring images of objects of interest into correspondence (so that the images fall on similar parts of both retinae)
![Page 9: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/9.jpg)
• since eyes are laterally separated in the head the optical axes of the two eyes are parallel only for fixation at infinity
• nearer targets require crossing one’s eyes (convergence)
![Page 10: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/10.jpg)
• Several catergories– tonic vergence– voluntary vergence or proximal vergence
• induced voluntarily or by an object that appears to be at a different distance
– accommodative vergence• when accommodating there is a link with vergence
that drives a compatible vergence change; also vergence accommodation
![Page 11: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/11.jpg)
• disparity vergence– vergence in response to
disparity in the images in the two eyes
– allows for aligning the images of the target in the two eyes
![Page 12: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/12.jpg)
Two main questions for us
1. Does vergence give a sense of depth?• could theoretically triangulate depth of target
from angle of convergence• static vergence is probably a fairly weak
indicator for distance judgements but• indirectly important for size and shape
perception, calibration of stereopsis• e.g. micropsia in the wallpaper effect• size and shape constancy
![Page 13: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/13.jpg)
• Dynamic vergence may play a role in signalling change in depth
• also controversial
• Regan (1986) found no changing depth from changing vergence in large stimuli but weak effect in small stimuli; substantial changes in apparent size
![Page 14: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/14.jpg)
2. Dissociation of accommodation and vergence
• Normally vergence, accommodation and pupil size are controlled in a tightly coupled manner (the ‘near triad’)
• In most binocular displays, the display is focused at a fixed distance and thus accommodation should be fixed
![Page 15: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/15.jpg)
• This fixed accommodation leads to vergence/accommodation mismatch– depth cue conflicts between vergence and
accommodation; stereopsis and blur
– difficulty in obtaining clear vision for stimuli requiring vergence nearer or further than the optical distance of the display OR
– difficulty ‘fusing’ stimuli
– contributes to eyestrain, simulator sickness
![Page 16: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/16.jpg)
– adaptation, re-adaptation, visual stress (seminar next week Wednesday)
![Page 17: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/17.jpg)
Stereoscopic vision
![Page 18: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/18.jpg)
Binocular Disparity
– Horizontal disparity arises from lateral separation of the eyes (parallax)
– Relative depth is coded by disparity scaled inversely by the square of viewing distance
(ad)
D2
– Stereopsis (solid sight) refers to depth perception from disparity
![Page 19: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/19.jpg)
Depth from Disparity
ScreenScreen
Fixation Point, FFixation Point, F
LeftLeftEyeEye
RightRightEyeEye
PP
FFPPRR PPLL
– Horizontal disparity arises from lateral separation of the eyes
2D
adLR
ScreenScreen
Fixation Point, FFixation Point, F
LeftLeftEyeEye
RightRightEyeEye
PP
FF PPRRPPLL
DD
dd
aa
![Page 20: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/20.jpg)
Stereoscopic Voxels
from Davis and Hodges 1995
![Page 21: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/21.jpg)
![Page 22: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/22.jpg)
![Page 23: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/23.jpg)
http://www.pandigitalmedia.com/bgussin
![Page 24: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/24.jpg)
Sensitivity to disparity
• People are extremely sensitive to relative disparity. Stereopsis is a hyperacuity– discrimination thresholds of a few seconds of arc
– Upper limit: patent versus qualitative stereopsis
• much poorer sensitivity to absolute disparity• thus very sensitive to depth differences between
stimuli; poor ability to estimate absolute distance
![Page 25: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/25.jpg)
Sensitivity to disparity
• Disparity has an inverse square dependence on distance
• Thus, stereopsis is most effective for estimating depth and surface shape at near distances
![Page 26: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/26.jpg)
Sensitivity to disparity
• many people are stereo-anomalous– cannot see depth from disparity (about 5% of
population) or– cannot see motion-in-depth from changing disparity
or– have deficits in particular part of the visual field, or
for crossed disparity, or for uncrossed disparity
• cannot rely on all subjects seeing stereoscopic depth
![Page 27: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/27.jpg)
• Two of the main issues in stereopsis are– matching of corresponding parts of the two
images – estimation of depth from disparities
![Page 28: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/28.jpg)
1 2 3
A B
Keplerian projection
Correspondence problem
• If features are similar a matching ambiguity arises
• Human stereopsis usually matches images very effectively
• Often the most difficult problem in stereoscopic computer vision
![Page 29: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/29.jpg)
Random-dot stereograms
![Page 30: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/30.jpg)
• not all features in one eye’s image have a corresponding feature in the other image
• these monocular zones play an important role in perception of objects and surface properties in binocular vision– depth from monocular occlusion– luster – binocular rivalry
![Page 31: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/31.jpg)
.
Opaque object
Left-eye monocular zone
Right-eye monocular zoneBinocular occlusion zone
(a) When a near occluding object is shorter than the interocular distance, both eyes see the region between the occlusion zones.
(b) When the occluding object is longer than the interocular dis-tance, neither eye sees the region between the monocular zones.
. .
Opaque object
Distant surface
Left-eye monocular zone
Right-eye monocular zone
Binocular zone
(c) The near object may not be visible to the left eye if near and far surfaces are similar. The object is camouflaged for this eye. The near object may be visible to the other eye against a different background. It appears on the nasal side of the far object.
Near object
Far object
.
A
d
C
g
fA
d
(d) Tracings of drawings made by Leonardo da Vinci to illustrate monocular occlusion zones created by looking through an aperture. (Adapted from Strong 1979)
![Page 32: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/32.jpg)
Fusion
• Typically a wide range of disparities present in a scene
• If disparities are modest people ‘fuse’ the images of the object in the left and right and perceive a unitary object
• Outside this range objects are seen doubly (diplopic) or one eye’s image is suppressed (binocular rivalry)
![Page 33: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/33.jpg)
Fusion
• Only a range of disparities near the horopter are seen singly (Panum’s fusional area)
• Also a limited range of disparities for which depth can be obtained from disparity. But depth can be seen in diplopic images
• Fusion depends on size, contrast, disparity gradient, temporal factors …
![Page 34: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/34.jpg)
Estimation of Depth from Disparity
• Relation between horizontal disparity and depth varies with distance and location of surface wrt head (recall the curvature of the horopter)
• Need to account for viewing system parameters of distance and eccentricity to judge– metric depth, relief, surface curvature, surface slant …
– absolute retinal disparity does not provide viewing system parameters need: ‘sensed’ eye position, vertical disparities, other depth cues, …
![Page 35: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/35.jpg)
Stereoscopic issues in displays
![Page 36: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/36.jpg)
• Types of display based on ‘ocularity’– Monocular : Image presented to one eye only
• no stereopsis, rivalry with dark images
– Biocular : same image presented to both eyes• Stereopsis specifies a flat surface
• stereoscopic artefacts can arise with misalignment
– Binocular : eye specific (dichoptic) images presented to each eye
• Stereoscopic imagery possible
• Autostereoscopic - binocular display that requires single display and no special eyewear
![Page 37: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/37.jpg)
• Methods of presenting stereoscopic displays– hmds– shutters– polaroid- linear, circular– anaglyphs– barrier, lenticular– holograms– ….
![Page 38: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/38.jpg)
![Page 39: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/39.jpg)
From www.stereographics.com
![Page 40: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/40.jpg)
From www.stereographics.com
![Page 41: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/41.jpg)
Example - 3ality autostereoscopic display
• Many new autostereoscopic displays based on lenticular sheets or parallax barrier methods – trade spatial resolution for stereopsis
• Shutter and some other systems trade temporal resolution for stereopsis (flicker)
• 3ality display codes stereoscopic information in luminance, preserving spatial and temporal resolution (at expense of dynamic range).
![Page 42: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/42.jpg)
![Page 43: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/43.jpg)
• Viewer wears glasses with a pair of orthogonal polarizing filters
• At each pixel, left eye should see a certain amount of light of one polarization, and the right eye a certain amount of the other
• Left and right eyes images mixed by summing luminance of the two images (vector sum) - ‘magnitude’ of the vector
![Page 44: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/44.jpg)
Images from Kleinberger et al, Stereoscopic Displays and Applications X, SPIE vol #5006
![Page 45: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/45.jpg)
• An ‘extra’ liquid crystal panel twists the light for each pixel to the appropriate intermediate polarization - ‘angle’ of the vector
• Eyewear decomposes the combined light into appropriate amount of left and right eye polarization
![Page 46: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/46.jpg)
![Page 47: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/47.jpg)
![Page 48: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/48.jpg)
Autostereoscopic version
![Page 49: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/49.jpg)
• When are stereo displays useful?– 3D visualisation– ambiguous/poor monocular information– static displays– direct 3D manipulation– cluttered, complicated scenes
![Page 50: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/50.jpg)
• some issues– field of view
– depth resolution
– ghosting and crosstalk
– refresh rate for time multiplexed techniques
– distortion, alignment and calibration
– focus
– head tracking, view dependence
– ‘orthostereoscopy’ vs visual comfort
![Page 51: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/51.jpg)
Generating Stereoscopic Displays
• A range of algorithms have been proposed to deal with generating stereoscopic imagery to deal with– fusion, focus problems– head movement– optimising range of depth portrayed
• we’ll look at these in next week’s seminars
![Page 52: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/52.jpg)
• Trade-offs in field of view in binocular displays– 100% overlap
• stereoscopic vision over the FOV
• less distortion effects
• total FOV is same as monocular FOV
![Page 53: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/53.jpg)
– Partial Overlap:• stereopsis restricted to binocular overlap region
• parts of normal binocular field sees monocular view: rivalry possible, no stereopsis
• total FOV exceeds monocular FOV
• distortion introduces disparity even if optics for the two eyes are matched
![Page 54: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/54.jpg)
Calibration and Alignment
• Calibration is critical for stereoscopic displays. Some parameters:– interpupillary distance (IPD)
• varies with subject 51mm ~ 76mm
• vergence changes effective IPD slightly (may be a small artifact in precise AR displays)
– convergence of the optics– relative rotational alignment of the displays– interocular differences in linearity, distortion, image
size
![Page 55: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/55.jpg)
• In stereoscopic displays relative misalignment may distort space
• Alignment is critical for tele-operation systems which fuse images from multiple sensors or in augmented reality
![Page 56: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/56.jpg)
• Distortion– Nonlinear mapping from object space to image
space arising from lens or display systems– radial distortions are common e.g. pincushion
or barrel distortions– for stereoscopic displays, distortion is
particularly troublesome when not matched in the two eyes
![Page 57: Cosc 6326/Psych6750X Vision and Visual Displays. Why do we have two eyes? Binocular vision has several advantages including –increased field of view –redundancy](https://reader036.vdocuments.net/reader036/viewer/2022081514/56649d0b5503460f949df673/html5/thumbnails/57.jpg)