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Computational Light Field window
Displays
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Douglas Lanman Matthew Hirsch
Sub bulletsMIT Media Lab
look like this MIT Media Lab
2. Is “glasses-free 3D” ready?
Nintendo 3DS MasterImage 3D Asus Eee Pad MeMO 3D LG Optimus 3D
E3 2010 Computex 2011 Computex 2011 Mobile World Congress 2011
Toshiba 3DTV Prototype Sony 3DTV Prototype LG 3DTV Prototype
CES 2011 CES 2011 CES 2011
3. Taxonomy of Direct 3D Displays:
Glasses-bound vs. Unencumbered Designs
Immersive
(blocks direct-viewing of real world)
Head-mounted
(eyepiece-objective and microdisplay)
See-through
(superimposes synthetic images onto real world)
Glasses-bound
Stereoscopic
Spatially-multiplexed (field-concurrent)
(color filters, polarizers, autostereograms, etc.)
Multiplexed
(stereo pair with same display surface)
Temporally-multiplexed (field-sequential)
(LCD shutter glasses)
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Multi-planar
Unencumbered (time-sequential projection onto swept surfaces)
Volumetric
(directly illuminate points within a volume) Transparent Substrates
Automultiscopic (intersecting laser beams, fog layers, etc.)
Static
(holographic films)
Holographic
(reconstructs wavefront using 2D element) Dynamic
(holovideo)
Taxonomy adapted from Hong Hua
4. Taxonomy of Direct 3D Displays:
Parallax Barriers
NewSight MV-42AD3 42''
(1920x1080, 1x8 views)
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements)
Unencumbered Volumetric
(directly illuminate points within a volume)
Automultiscopic
Holographic
(reconstructs wavefront using 2D element)
5. Taxonomy of Direct 3D Displays:
Integral Imaging
Alioscopy 3DHD 42''
(1920x1200, 1x8 views)
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Unencumbered Volumetric
(directly illuminate points within a volume)
Automultiscopic
Holographic
(reconstructs wavefront using 2D element)
6. Directional Backlighting
Nelson and Brott, 2010
US Patent 7,847,869
Currently promoted by 3M
Requires a high-speed (120 Hz) LCD panel, an additional double-sided prism film, and a pair of LEDs
Allows multi-view display, but requires higher-speed LCD and additional light sources for each view
7. Taxonomy of Direct 3D Displays:
Multi-planar Volumetric Displays
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Multi-planar
Unencumbered (time-sequential projection onto swept surfaces)
Volumetric
(directly illuminate points within a volume)
Automultiscopic
Holographic
(reconstructs wavefront using 2D element)
8. Taxonomy of Direct 3D Displays:
Transparent-substrate Volumetric Displays
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Multi-planar
Unencumbered (time-sequential projection onto swept surfaces)
Volumetric
(directly illuminate points within a volume) Transparent Substrates
Automultiscopic (intersecting laser beams, fog layers, etc.)
Holographic
(reconstructs wavefront using 2D element)
9. Taxonomy of Direct 3D Displays:
Static Holograms
capture reconstruction
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Multi-planar
Unencumbered (time-sequential projection onto swept surfaces)
Volumetric
(directly illuminate points within a volume) Transparent Substrates
Automultiscopic (intersecting laser beams, fog layers, etc.)
Static
(holographic films)
Holographic
(reconstructs wavefront using 2D element)
10. Taxonomy of Direct 3D Displays:
Dynamic Holograms (Holovideo)
Tay et al. MIT Media Lab Spatial Imaging Group
[Nature, 2008] [Holovideo, 1989 – present]
Parallax Barriers
(uniform array of 1D slits or 2D pinhole arrays)
Parallax-based
(2D display with light-directing elements) Integral Imaging
(lenticular sheets or fly’s eye lenslet arrays)
Multi-planar
Unencumbered (time-sequential projection onto swept surfaces)
Volumetric
(directly illuminate points within a volume) Transparent Substrates
Automultiscopic (intersecting laser beams, fog layers, etc.)
Static
(holographic films)
Holographic
(reconstructs wavefront using 2D element) Dynamic
(holovideo)
11. What is meant by “glasses-free 3D”?
binocular disparity convergence motion parallax accommodation/blur
current glasses-based (stereoscopic) displays
near-term glasses-free (automultiscopic) displays
longer-term volumetric and holographic displays
12. Design Trade-offs
Integral Imaging Parallax Barriers Directional Backlighting
Integral Imaging Parallax Barriers Directional Backlighting
Spatial Resolution low low high
Brightness high low moderate
Cost low low – moderate moderate – high
Full-resolution 2D no yes (dual-layer LCD) yes
Motion Parallax yes yes no
13. Generalizing Parallax Barriers
mask K
…
mask 3
mask 2 mask 2 mask 2
mask 1 mask 1 mask 1
light box light box light box
Conventional Parallax Barrier High-Rank 3D (HR3D) Layered 3D and Polarization Fields
Parallax barriers use heuristic design: front mask with slits/pinholes, rear mask with interlaced views
High-Rank 3D (HR3D) considers dual-layer design with arbitrary opacity and temporal multiplexing
Layered 3D and Polarization Fields considers multi-layer design without temporal multiplexing
19. Tomographic Light Field Synthesis
virtual plane
Image formation model:
ò
- m (r )dr
attenuator
L(x, q ) = I 0 e C
æ L(x, q ) ö
L(x, q ) = ln ç ÷ = - ò m (r)dr
è I0 ø C
backlight l = -Pa
Tomographic synthesis:
2
arg min l + Pa , for a ³ 0
a
2D Light Field
20. Tomographic Light Field Synthesis
virtual plane
Image formation model:
ò
- m (r )dr
attenuator
L(x, q ) = I 0 e C
æ L(x, q ) ö
L(x, q ) = ln ç ÷ = - ò m (r)dr
è I0 ø C
backlight l = -Pa
Tomographic synthesis:
2
arg min l + Pa , for a ³ 0
a
2D Light Field
21. Multi-Layer Light Field Decomposition
Reconstructed Views
Target 4D Light Field
Multi-Layer Decomposition
22. Prototype Layered 3D Display
Transparency stack with acrylic spacers Prototype in front of LCD (backlight source)
35. Polarization Field Displaysviewer moves right
viewer moves down
Stacked Polarization
Input 4D Light Field Rotating Layers
90°
0°
Optimized Rotation Angles for Each Layer
42. Analysis of Parallax Barriers
k
L[i,k]
i
k
g[k]
f[i]
i
L[i,k]
`
light box
L[i, k] = f [i]× g[k] L[i, k ] f [i] g[k ]
43. Analysis of Parallax Barriers
L[i,k]
k
g[k]
i
f[i] `
light box
T
Ken Perlin et al. An Autosteroscopic Display. 2000. L[i, k] = å ft [i] Ä gt [k]
Yunhee Kim et al. Electrically Movable Pinhole Arrays. 2007.
t=1
49. Prototype High-Rank 3D (HR3D) Display
http://cameraculture.media.mit.edu/byo3d
Matthew Hirsch and Douglas Lanman. Build Your Own 3D Display. SIGGRAPH 2010, SIGGRAPH Asia 2010, SIGGRAPH 2011.
52. High-Rank 3D (HR3D) Layered 3D Polarization Fields
www.hr3d.info www.layered3d.info tinyurl.com/polarization-fields
BiDi Screen Tensor Displays
www.bidiscreen.com tinyurl.com/tensordisplays
Notes de l'éditeur
Basically, the tomographic light field synthesis then boils down to solving a linear equation system of the form Ax=b. b is the target light field, A the projection matrix, and the unknowns x are the LCD pixel values
This equation system can be solved with SART – a technique developed, tested, and refined over decades in the medical imaging community.Algorithm is very simple:Initialize some data and find an initial guess of the pixel valuesIteratively update and clamp the solutionUpdate rules require two important operations: a function computing the matrix-vector multiplication Ax, and a function computing the transpose matrix-vector multiplication ATv