1. copyright@Jung,Bily,Jingjing 20/10/2004 Display Technology: Stereo&3D Display Technologies David F. McAllister Department of Computer Science North Carolina State University Raleigh, NC 27695-8206 Tel:919-233-8164 Fax:919-233-8578 Email: david@cmonline.com

2. copyright@Jung,Bily,Jingjing 20/10/2004 Recently there have been rapid advancements in 3D techniques and technologies. Old techniques have been improved, and new ones have been developed. Our brain integrates these two images into one three- dimensional picture.

3. copyright@Jung,Bily,Jingjing 20/10/2004 Overview Introduction Depth Cues Physiological Depth Cues Psychological Depth Cues A Technology Taxonomy Stereo Pairs Display Technology Overview Separating Left and Right Eye Views Cross Talk Field Sequential Techniques Time-Parallel Techniques

4. copyright@Jung,Bily,Jingjing 20/10/2004 Accommodation ( short viewing distances ) Process of lens changing shape Convergence ( short viewing distances ) Inward rotation of eyes Binocular disparity ( medium viewing distances ) Difference in the images projected on the left and right eye retinas Motion parallax Different view of a scene in response to movement Physiological depth cues Psychological depth cues

5. copyright@Jung,Bily,Jingjing 20/10/2004 http://info.geography.siu.edu/people/oyana/Teaching/485_551/5th_lecture.htm single-image random dot stereograms created by Peter Chang and Gareth Richards in EnglandPeter Chang and Gareth Richards in England

6. copyright@Jung,Bily,Jingjing 20/10/2004 Linear perspective Shading and shadowing Physiological depth cues Psychological depth cues

7. copyright@Jung,Bily,Jingjing 20/10/2004 Aerial perspective Interposition Physiological depth cues Psychological depth cues

8. copyright@Jung,Bily,Jingjing 20/10/2004 Retinal image size Texture gradient Color Physiological depth cues Psychological depth cues

9. copyright@Jung,Bily,Jingjing 20/10/2004 Stereo pair Holographic Multiplanar (Volumetric) Physiological depth cues Psychological depth cues

10. copyright@Jung,Bily,Jingjing 20/10/2004 Physiological depth cues Stereo Pairs Stereo Pairs Psychological depth cues

11. copyright@Jung,Bily,Jingjing 20/10/2004 Stereo Pairs Horizontal disparity Left Image+ Right Image=Spatial Images Two interleaved images unite as one.

12. copyright@Jung,Bily,Jingjing 20/10/2004 Vertical disparity Correct Incorrect Physiological depth cues Psychological depth cues

13. copyright@Jung,Bily,Jingjing 20/10/2004 Cross talk is when left images reach right eye, and right images reach left eye Introduction Depth Cues Physiological Depth Cues Psychological Depth Cues A Technology Taxonomy Stereo Pairs Display Technology Overview Separating Left and Right Eye Views Cross Talk Field Sequential Techniques Time-Parallel Techniques

14. copyright@Jung,Bily,Jingjing 20/10/2004 Images are presented alternately Most common techniques is shutter glass stereo Takes advantage of persistence of vision Frame rate must be very high Field Sequential Techniques Time-Parallel Techniques

15. copyright@Jung,Bily,Jingjing 20/10/2004 Both views are presented simultaneously Dual viewing: Anaglyph (red/green) glasses Polarised glasses Main issue is cross—talk Separate viewing: Head--mounted displays Time-Parallel Techniques Field Sequential Techniques

16. copyright@Jung,Bily,Jingjing 20/10/2004 Overview 3D Displays:Viewing Devices Required Field Sequential Devices CrystalEyes ZScreen system Pulfrich Technique FakeSpace PUSH Display Work Bench Displays VREX Micropolarizers Large Format Displays IMAX Fakespace Systems Displays The VisionDome

17. copyright@Jung,Bily,Jingjing 20/10/2004 Glasses: LCD ‘shutter’ or active stereo (most systems)---e.g. CrystalEyes LCD display technology Two crossed,polarized layers per eye One permanently polarized One switchable Controlled by an IR signal Cross polarized or ‘passive’ stereo (e.g. IMAX / ZSreen glasses) two lenses Polarized in orthogonal directions Two projectors produce different images --Polarize with filters

18. copyright@Jung,Bily,Jingjing 20/10/2004 What is a CrystalEyes like? What is it? One kind of stereo shutter glasses,using active glass system How does it work? Creates illusion of stereo by alternating left and right eye iimages between frames Glasses alternately block out each eye so that each eye sees every other image Requires very high refresh rates Currently used for many systems including CAVE Property merit A high dynamic range----ensure that only the correct image is shown to each eye. Not suffer from ghosting and double-images result Disadvantages Display system must have a very high frame rate Glasses must have some power supply so batteries or wires are required CrystalEyes Field Sequential Devices Pulfrich Technique FakeSpace PUSH Display ZScreen system Work Bench Displays VREX Micropolarizers

19. copyright@Jung,Bily,Jingjing 20/10/2004 Physiological depth cues Pulfrich Technique FakeSpace PUSH Display ZScreen system What is it? Passive glass system Polarized glasses How does it work Property Advantages: don’t need as quick of a refresh rate as you do with shutter glasses cheap an require no power supply Disavantages: low dynamic range, may suffer from ghosting or image cross talk. Solution to prevent ghosting electrode-segmentation------increasing the effective dynamic range of the system and produces a high quality stereo image Work Bench Displays VREX Micropolarizers

20. copyright@Jung,Bily,Jingjing 20/10/2004 Ploarized glasses Cheap Light and comfortable More or less indestructible Continuous image in both eyes (2 projectors) Two projectors---alignment issues Non-polarizing screen required 50% light loss Can’t tilt your head more than a few Degrees Shutters vs polarization Expensive( ~$250+) One display(Screen or projector) Heavier and more uncomfortable --Batteries and electronics inside Batteries run out – maintenance issues Much more fragile 50% light loss ---could avoid with two active layers

21. copyright@Jung,Bily,Jingjing 20/10/2004 CrystalEyes Field Sequential Devices Pulfrich Technique ZScreen system Pulfrich Effect This effect is called Pulfrich-effect in honor of the german physicist Carl Pulfrich (1858-1927). When viewing a moving image,the user can see two different images if a filter is placed over one eye Usually a neutral-density filter Also works with sunglasses with one lens removed The perception in the covered eye is slowed,thus that eye sees an older image If the images are created correctly(for example,rotating the scene about a vertical axis),the current image and the delayed image will form a stereo pair Cheap and capable of being broadcast,but requires constant motion Fakespace push display Work Bench Displays VREX Micropolarizers Pulfrich-Glasses The darkened eye reacts slower to optical stimuli. It's based on a time-parallax in horizontally moving objects. The parallax is determined by the speed of movement. In case the movement stops the image turns 2D.

22. copyright@Jung,Bily,Jingjing 20/10/2004 Fakespace push display Work Bench Displays VREX Micropolarizers Pulfrich Technique CrystalEyes Field Sequential Devices ZScreen system How does it work? using a box shaped binocular viewing device with attached handles which is mounted on a triad of cylindrical sensors.

23. copyright@Jung,Bily,Jingjing 20/10/2004 ‘Workbench’ Similar to a wall display Tiltable Possibly can be made flat Usually used with tracking Usually used by one person Used as a wide screen monitor Using active glasses stereo technique User has very little room to move around Field of regard is small Fakespace push display Work Bench Displays VREX Micropolarizers Pulfrich Technique CrystalEyes ZScreen system Field Sequential Devices Fakespace ImmersaDesk R2 Fakespace ImmersaDes M1 FakeSpace ImmersaDesk A “portable” semi-immersive environment: VR ‘Responsive’Workbench

24. copyright@Jung,Bily,Jingjing 20/10/2004 What is it? an optical device that can change the polarization of an LCD display on a line by line basis. How does it work A periodic array of microscopically small polarizers that spatially alternate between mutually perpendicular polarizing states. Passive polarized glasses are needed to view the image Requiring a single-frame stereoscopic image format combining a left-eye perspective view with a right-eye perspective view to form as composite image,which contains both left and right- eye information alternating on a line-by- line basis. VREX Micropolarizers Pulfrich Technique CrystalEyes Field Sequential Devices ZScreen system Fakespace push display Work Bench Displays

25. copyright@Jung,Bily,Jingjing 20/10/2004 IMAX Fakespace Systems Displays The Vision Dome How does it work How does it work when projecting stereo,IMAX uses the standard field sequential polarized projection mechanism where the user wears passive glasses. when projecting stereo,IMAX uses the standard field sequential polarized projection mechanism where the user wears passive glasses. allow multiple users allow multiple users IMAX SCREEN IMAX PROJECTOR

26. copyright@Jung,Bily,Jingjing 20/10/2004 IMAX Fakespace Systems Displays The Vision Dome One kind of immersive technology 4-sided Cave UCL’s Cave 4-sided CAVE in UNIMAS VR Lab, Kota Samarahan, Sarawak IMAX a Extension of flat screen stereo—Cave Small room theatre Back-projected screens: walls,Floor,Ceiling required active shuttering glasses Any combination from 2-6 sides of box Designed to avoid HMD(Head Mouted Device) limitations on update rate

27. copyright@Jung,Bily,Jingjing 20/10/2004 When the idea of a CAVE was conceived,it was originally supposed to be 6-sided. 6-sided CAVE –2.5m x 2.5m x 2.5m –Back projektion –Aktive stereo –1 person with tracking, + a few observers without tracking IMAX The Vision Dome IMAX Fakespace Systems Displays

28. copyright@Jung,Bily,Jingjing 20/10/2004 A another Extension of flat screen stereo—GeoWall The GeoWall created to be a cheap and portable alternative to the CAVE Uses two projectors and polarized light glasses (passive glasses system) Can be used for an entire classroom full of people IMAX The Vision Dome IMAX Fakespace Systems Displays The Vision Dome

29. copyright@Jung,Bily,Jingjing 20/10/2004 What is it? Multiple projector system Project onto domed surface overhe-ad Can cover as much as 180 or more 180*180 ---Hayden Planetarium (Trimension) Using distorted images: IMAX Fakespace Systems Displays The Vision Dome How the environments looks in it? Distorted images

30. copyright@Jung,Bily,Jingjing 20/10/2004 Alternating Pairs Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Autostreoscopic Displays Volumetric Displays Overview

31. copyright@Jung,Bily,Jingjing 20/10/2004 Alternating Pairs Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Autostreoscopic Displays Figure 1 VISIDEP

32. copyright@Jung,Bily,Jingjing 20/10/2004 Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror - A mechanical moving slit display - Popularized by Homer Tilton - Parallactiscope - No commercially viable products Autostreoscopic Displays

33. copyright@Jung,Bily,Jingjing 20/10/2004 The DTI System Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Figure 2 - Each stereoscopic image is half the full resolution of the screen -The stereoscopic display is quite sensitive to the position of the viewer’s head Autostreoscopic Displays Figure 3 From above

34. copyright@Jung,Bily,Jingjing 20/10/2004 Seaphone Display Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror - A right eye system, a left eye system and head tracking system - The stereo viewing area determines the number of viewers Autostreoscopic Displays Figure 4

35. copyright@Jung,Bily,Jingjing 20/10/2004 Seaphone Display Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Autostreoscopic Displays Figure 5

36. copyright@Jung,Bily,Jingjing 20/10/2004 The Sanyo Display Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Autostreoscopic Displays -Use LC technology -Head tracking System -Use two image splitter - No ghosting

37. copyright@Jung,Bily,Jingjing 20/10/2004 The HinesLab Display Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Autostreoscopic Displays Figure 6

38. copyright@Jung,Bily,Jingjing 20/10/2004 Oscillating Plane Mirror Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Volumetric Display - No disconnection of accommodation - All depth cues would be consistent - According to the focal length of The mirror, dramatic improvement in view volume depth can be obtained.

39. copyright@Jung,Bily,Jingjing 20/10/2004 Varifocal Mirror Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Volumetric Display - A commercial multiplanar - Use a flexible circular mirror anchored at the edges.

40. copyright@Jung,Bily,Jingjing 20/10/2004 Rotating Mirror Moving Slit Parallax Barrier The DTI System Seaphone Display The Sanyo Display The HinesLab Display Alternating Pairs Oscillating Plane Mirror Varifocal Mirror Rotating Mirror Volumetric Display -Use RGB lasers for point plotting and a double helix mirror rotating at 600 rpm as reflecting device