My Categorization

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My Categorization

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

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Tradeoffs Considered

• 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?

Cost Usability Effectiveness Multi-viewer Ani
mation
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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

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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!

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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)

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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

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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

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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)

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Note that barrier spacing is different than image
slit spacing
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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

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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)

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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

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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

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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!

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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

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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

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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

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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

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Remarks

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

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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

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Nerd.
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Remarks

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

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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