1

How Much Reality? Comfortable 3-D viaSingle Lens Stereo

Kartik Thumbavanam PadmanabhanAdvisor : Prof. Mel Siegel

2

How do we humans perceive depth?

How do we see the world in 3-D ?Principle of stereoscopy

3

Depth Cues

Binocular Parallax Convergence and AccommodationPrimary Cue – Binocular DisparityOther Cues

OcclusionRelative SizeSuperposition

4

Binocular Parallax"apparent motion" or a “perspective shift”

5

ConvergenceSimultaneous inward movement of both eyes toward each other

6

Accommodation

Expansion and contraction of ciliarymuscles

7

Primary Cue-Binocular Disparity

8

Is More Disparity Good ?

Conventional Binocular StereoscopyHigh Intraocular separation – High disparity

IssuesTime to fuseEye strain

Disparity α 1/(Ease Of Fusion)

9

How much disparity is just enough ?

How much intraocular separations?Big enough to stimulate stereopsisAllow strain free viewing

Intraocular separations of 1-3mm of human 60-65mm

10

Solution :Single Lens Stereoscopy

Light striking different sub-regions of aperture are differentDifferentiate two views in a single optic path

11

Techniques Implemented

Single Optic PathSpatial Domain

Anaglyphic StereoscopyTemporal and Spatial Domain

Light Valve Technique

12

Anaglyphically Encoded Single Lens

StereoscopyColor Filters

Subtractive FilteringRed/Blue color encoded viewsDecoded by Anaglyph glasses

13

Relative Disparity

14

Why is this technique not preferred ?

Increased Eye-channel crosstalkLack of brightnessRetinal RivalryColor Bombardment

15

Single Lens Stereo via Light ValvesLCD Shutters

http://electronics.howstuffworks.com/lcd3.htm

16

Experimental Setup12V DC

120V AC

Controller Box

Camera

TV

17

Advantages

More LightLess Cross-talkNo retinal rivalryNo color bombardment

18

Experiments

Goal of experimentsExperiments

Quantitave Comparison of the study of Binocular Stereo vs. Single Lens

Eye StrainDepth PerceptionTime of Fusion

19

Nature Of Experiments

Involving less learningLess human brain-eye co-ordinationHelpful in predicting the depth cuesTo validate the single-lens stereo in more quantitave mannerExperiments performed using brainteasers, loop-trapping puzzles, Rubix cube and Pick and Place experiments

20

Experimented Conditions:Each of the above 4 experiments are performed under 5 different conditions with total of 18 subjects:

• Direct Vision Two Eyes • Direct Vision One Eye • Direct Vision Monoscopic • Binocular Stereo • Single-Lens Stereo

21

ScreenshotsNo Stereo

Binocular Stereo Single-Lens Stereo

22

Observations:Eye Strain: Less Stressful Direct Vision Two Eyes <Direct Vision One Eye < Single Lens Stereo < Direct Vision Monoscopic < Binocular Stereo More StressfulPerspective distortion was noticed frequently when the experiments were done near camera.Motion parallax was noticed in pick and place operation when the part of background was made moving. (noticed very recently)

23

Observations…contd.The standard deviations obtained in any case was less whenever there was a ‘trick’ associated with the experiment irrespective of conditions. There was a little learning associated to Pick and place and Rubix cube experiment and more learning in case of brainteasers.Overall spread of standard deviations were in the order: Direct Vision Two Eyes < Direct Vision One Eye < Single Lens Stereo < Direct Vision Monoscopic < Binocular Stereo

24

Conclusions from experiments

Very apparent viewing comfort with Single Lens Stereo with no compromise on depth perceptionTime to fuse is less for Single Lens StereoFocusing closer to the object enhances depth perceptionDepth cues are exploited in a quantitative way.

25

Thank you