My Categorization

2. My Categorization • Free-Viewing Displays • SIRDS • Stereo Pairs • Barrier-Strip • Lenticular • Aided-Viewing Displays • Anaglyph • Polarized • Field-Sequential

3. Tradeoffs Considered Cost Usability Effectiveness Multi-viewer Animation • How easy/cheap is it to construct? • How easy is it to view? • How pronounced is the effect? • How many people can view the display with stereopsis at the same time? • How easy is it to make an animated version of the display?

4. Displays for the naked eye • Multi-viewer is easy because people come naturally equipped • Cost, usability, effectivness, and animation vary greatly • SIRDS • Stereo Pairs • Barrier-Strip • Lenticular

5. Single Image Random Dot Stereograms (SIRDS) • Commonly known as “Magic Eye” • Appear to be noise -- they are! (with constrains) • Guide dots (if provided) indicate propert convergence depth • Only depth cue is stereo-disparity so the stereo-blind(10% of population) never see anything but noise!

7. Remarks • Notoriously difficult to view • Encode little visual information • Depth data is quantized (integral pixel offsets) • Extremely cheap to produce (with a computer) • Animation is possible (makes them easier to view as well)

8. Stereo Image Pairs • Simplest form of autostereograms • Landmarks in image act a guides to aid in finding proper convergence • More angular adjustment of eyes is required than in SIRDS • Higher image quality at the cost of more difficult viewing

10. Remarks • Simplest to produce (darkroom, hand, software,etc.) • Compelling depth effect • Viewable by many people at once • High-strain with extended viewing • Strain limits animation

11. Barrier Strip Displays • Making viewers consciously adjust their ocular convergence is uncomfortable for some, impossible for others. • Barrier strip displays use a grill of occluding elements to block view of images from either eye • Viewers must be in certain locations to see effect (angle and distance are tuned)

12. Note that barrier spacing is different than image slit spacing

13. Remarks • Encode clean stereo disparity information • Comfortable for extended viewing (natural convergence point) • Barriers block 50% of light going in and out, usually requres backlighting • Harder to construct (ugly trig) • Rigid and expensive (structure requred to maintain barrier spacing) • Animation is no harder than still • Commercial equipment available for medical imaging

14. Lenticular Displays • Defeat brightness problem of BS by controlling ray path with lenses instead of barriers • Array of long cylindrical lenses (per pixel column) refract light to places with same distance constraint as BS, continuous angle • 100% of light passes in and out, no backlighting necessary • Wider field of view (limited by TIR and self-occlusion)

16. Remarks • Animation is possible with still source images using motion of viewer • Able to ~reproduce lightfield • More expensive/complex than BS with higher quality and less contraints • Drop-in graphics libraries can turn any 3d program into a lenticular display source

17. Displays with special viewing hardware • Hardware can enable better {usability, effectiveness, multi-viewer, animation} at the cost of cost -- the normal technology vs nature tradeoff. • Anaglyph • Polarized • Field-sequential • Dual display

18. Anaglyph • Nerdy/Cool red-blue glasses • Cyan, not blue! • Two images overlap (like SIRDS) but are differentiated by color • Filters over each eye collect light from one image but not the other • Works based on intensity of light -- colorblind people see them fine!

20. Remarks • Convergence is natural • Crosstalk can be annoying • “Color bombardment” causes strain and after-effects • Strain limits long term viewing • Same depth resolution/quality as raw stereo pair • Small incremental cost • Easy to make with (software/hand) • Animation is easy

21. Polarized Displays • Approach is similar to anaglyph • Polarization differentiates L-R channels • Requires two polarized light projectors (instead of just a printed page) • Screen must be polarization-preserving • Light loss and crosstalk occur when uses tilt head

23. Remarks • The cost-wise step up from anaglyph • Completely natural viewing experience • No strain (unless glasses cramp your style) • Ideal for theaters (IMAX), because high up-front costs and low incremental costs

24. Field Sequential Displays • Polarized projectors and screens do not make economic sense on a single-user scale • Move system complexity to the glasses from the display • LCD shutters over each eye control light flow from conventional display (monitor/projector) • Inexpensive control box triggers shutter • Several (expensive) glasses can be driven by one control box

25. Liquid Crystal Shutter Glasses L R End of each scan-line.

26. Remarks • Convergence is natural (still) • Some crosstalk can occur with lingering phosphors, slow shutters, synchronization issues • Cost is proportional to the number of viewers

27. Dual Displays • Enough monkey business, just stick a monitor in front of each eye. • Heavy (and expensive) headgear provides bright, immersive experience • Can be combined with headphones and head tracking to modify experience based on head movement

28. Nerd.

29. Remarks • Expensive • Completely natural focus (lenses embedded in headgear) • Very effective • Animation is standard • Only one user at a time • Prices are dropping

30. Conclusions • Noooooo! My awesome comparison matrix is gone! • Usability • Lenticular and dual displays are best • Effectiveness • SIRDS and anaglyph are the worst • Multi-viewer • Barrier-strip and dual displays have the most constrains • Animation • Its always possible but strain limits application to videos