Depth perception
1 Images removed due to copyright restrictions.
Please refer to lecture video
2 Cues used for coding depth in the brain
Oculomotor cues Visual cues
accommodation Binocular vergence stereopsis
Monocular motion parallax shading interposition size perspective
3 Stereopsis, basic facts and demos
4 Two simple methods for creating stereo images
1 2
stereo camera swiveled regular camera
5 Image is in public domain.
Demos, page 1
6 Images removed due to copyright restrictions.
Please see lecture video or Figure 1 of Schiller, Peter H., Geoffrey L. Kendall, et al. "Depth Perception, Binocular Integration and Hand-Eye Coordination in Intact and Stereo Impaired Human Subjects." Journal of Clinical & Experimental Ophthalmology 3, (210).
Demos, page 1 & 2
7 Autostereogram from Magic Eye
Images removed due to copyright restrictions.
Please see lecture video or the autostereogram from The Magic Eye, Volume I: A New Way of Looking at the World. Andrews McMeel Publishing, 1993.
Autostereograms: see Howard and Rogers, Depth Perception, Vol 2, pp. 549-556.
Demos, page 3
8 Retinal disparity utilized for stereopsis
Target hits corresponding retinal points Target hits non-corresponding retinal points target
fix fix target
Vieth-Muller circle
y y x x x = y x = y
9 Stereopsis, neuronal responses
10 V1 cell response to drifting bars at varied stereo depths
0.58 +6.0 +4.0
0.21 +2.0 +1.5 +1.0 +0.5 _ 0 38 + 0
-0.5 Depth (cm)
-1.0 Disparity (degree) -1.5 -0.23 -2.0 -4.0 -6.0 -1.13 -8.0 -10O
3O
0 1 2 O sec 0.14
Image by MIT OpenCourseWare. 11 V1 cell response to drifting bars at varied stereo depths
0.88 +10.0 +8.0 +6.0 +4.0 0.31 +3.0 +2.0 +1.0 +1.0 _ 0 38 + 0 Depth (cm) -0.5
Disparity (degree) -1.0
-0.23 -2.0 -4.0 -6.0 -1.13 -8.0
0
4O
0 1 2 3 0.18o sec
R 38 L
Key down
Image by MIT OpenCourseWare. 12 Basic cell types for stereo
Tuned excitatory far Tuned excitatory near Tuned excitatory zero 100 150 100 125 75 75 100
50 75 50 50 25 25 L R 25
0 0 0 .10 .05 00 05 10 .10 .05 00 05 10 .05 00 05
100 75 100 Tuned inhibitory Far Neural responses (impulses per sec) Neural responses (impulses Near 75 75 50 50 50 25 25 25
0 0 0 .10 .05 00 05 10 .10 .05 00 05 10 .10 .05 00 05 10 Horizontal display (deg)
Image by MIT OpenCourseWare.
13 Basic cell types for stereo
Tuned excitatory Near
] Far Neural activity ]
Tuned inhibitory
Near Fixation point Far Depth
Image by MIT OpenCourseWare.
14 The effects of V4 and MT lesions on stereoscopic depth perception
15 Images removed due to copyright restrictions.
Please see lecture video or Figure 1 of Schiller, Peter H., Geoffrey L. Kendall, et al. "Depth Perception, Binocular Integration and Hand-Eye Coordination in Intact and Stereo Impaired Human Subjects. "Journal of Clinical & Experimental Ophthalmology 3, (210).
16 Stereopsis
Graphs removed due to copyright restrictions.
Please see lecture video or Schiller, Peter H. "The Effects of V4 and Middle Temporal (MT) Area Lesions on Visual Performance in the Rhesus Monkey." Visual Neuroscience 10, no. 4 (1993): 717-46.
17 Motion parallax
18 MOTION PARALLAX, the eye is stationary
A B C
Velocity of motion: A fastest, C slowest, creating velocity gradient With rigidity constraint highest relative velocity is judged to be closest
19 MOTION PARALLAX, the eye tracks
1 a
2
b eye movement object motion a
1
The eye tracks the circle, which therefore remains stationary on the fovea
Objects nearer than the one tracked move 2 b at greater velocities on the retinal surface than objects further; the further objects actually move in the opposite direction on the retina. 20 21 Motion parallax
To derive depth information from motion parallax neurons are needed that provide information about velocity and direction of motion and perhaps also about differential motion.
The majority of cells in V1 are direction and velocity selective. Some appear also to be selective for differential motion.
Cells that process motion parallax have also been found in MT.
22 Brain activation by stereopsis and motion parallax in normal and stereoblind subjects with fMRI
23 Images are projected here
24 25
A: Stereo
27 B: Parallax
28 C: Stereo + Parallax
29 Shading
30 31 32 TheThe powerpower ofof shadingshading forfor depthdepth perceptionperception
33 Examples of the 12 different shadings used
34 The next five displays have identical, repeating elements which are shaded differently in each set yielding a variety of stable and conflicting percepts
35 36 37 38 39 40 Stereo and shading in harmony and in conflict
Demos, page 4-7
41 f f f
42 43 44 Putting stereo, parallax and shading together
45 3HUFHSWLRQ 35, no. 11 (2006): 1521.
about the visual system."
about the
Image removed due to copyright restrictions.
Please see lecture video or see Display 24 of Schiller, Peter H., and Christina E. Carvey. "Demonstrations of Spatiotemporal Integration and What they Tell us About the Visual System." Perception 35, no. 11 (2006): 1521.
46 Separate and combined disparity, parallax and shading depth cues
Graphs removed due to copyright restrictions.
Please see lecture video or Figure 3a,b of Schiller, Peter H., Warren M. Slocum, et al. "The Integration of Disparity, Shading and Motion Parallax Cues for Depth Perception in Humans and Monkeys." Brain Research 1377 (2011): 67-77.
47 Perspective
48 Image removed due to copyright restrictions.
Please see lecture video or see William O'Brian, "Because it's here, that's why," New Yorker, September 21, 1963, 42.
49 50 51 52 53 Perspective illusion
54 55 The Savage family
Painting is in public domain. Edward Savage 56 Hand-eye coordination and Binocular integration tests
57 Needle test
58 Movie of needle test needle_binoc needle_monoc
59 Touch-panel test
60 Examples of test of binocular integration
61 Binocular integration test, figures
A
B
62 Binocular integration test, words
S U D T R Y A S U D T R Y
B SSTT UU RR DD YY SSTT UU RR DD YY
63 Summary, depth:
1. Numerous mechanisms for analyzing depth have been identified that include vergence and accommodation, stereopsis, parallax, shading, and perspective.
2. Several cortical structures process stereopsis utilizing disparity information; the number of disparities represented is limited as in the case of color coding.
3. Utilizing motion parallax for depth processing necessitates neurons specific for direction, velocity and differential velocity; several areas, including V1 and MT process motion parallax.
4. Area MT contributes to the analysis of motion, motion parallax, depth, and flicker; however, these analyses are also carried out by several other structures.
5. Litte is known at present about the manner in which information about shading and perspective is analyzed by the brain.
64 MIT OpenCourseWare http://ocw.mit.edu
9.04 Sensory Systems Fall 2013
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