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What’s on page 13-25? Tom Butkiewicz
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What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Dec 21, 2015

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Page 1: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

What’s on page 13-25?

Tom Butkiewicz

Page 2: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 3: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 4: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Refresh Rates

• Flicker from shutter systems

• Halve refresh rates

• 2 eyed 120Hz != 1 eyed 60Hz

• Phosphors

• 2 Polarized Monitors + Half Silvered Monitor

Page 5: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Brightness

• Filter glasses – remove frequencies– dim images

• Shutter glasses– Brightness halved over time– Never 100% clear (shutter and polarized)

Page 6: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 7: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Example

• Hypothetical stereoscopic display

• Standard CRT

• LCD shutter glasses

Page 8: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

• Spatial resolution– Res = 1280 x 1024– Shutter cut vertical in half– Res = 1280 x 512

• Angular resolution– “comfortable viewing distance” = 18 inches– Screen size = 33” x 26”– Φ = 1.9 min x 3.8 min = 1.9’ x 3.8’

• Pixel Pitch– Pitch = (33cm/1280) = (26cm/1024)

= .025cm/pixel

Page 9: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

• Field of view– FOV = 40° x 32°

• Depth resolution– (0.00025 x 0.46) / (0.65 – 0.00025) = 0.0018m

• Refresh rate:– 120Hz refresh rate = 60Hz per eye

• Brightness:– LCD shutter transmits 30% of light– Screen seen 50% of the time– Overall: brightness = 15%

Page 10: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Interactive Stereoscopic Display

• Autostereoscopic displays:– Advantages:

• No viewing aids required• Multiple 3D views of the scene

• Interactive systems can achieve this viewpoint-dependence– Head Tracking (HMDs and HTDs)

Page 11: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 12: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Example

• Same system as before– Add head tracking

• Interactive• Motion parallax

• Head / Boom system

Page 13: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

• Same typical monitor– 1280x1024

• Special optics– 90° field of view for each eye– Partially overlapping– FOV = 135° x 90°– Φ = 90° / 1280 = 4.2’ = 0.0012 radians– Coarse resolution

• Easily change optics to suit different tasks– FOV vs Angular Resolution

Page 14: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

• Depth resolution– Must calculate the pitch for infinite-focus

screen at 46cm:• Pitch = 0.0012 x 46cm = 0.056 cm

– D = (0.00056 x 0.46) / (0.065 – 0.00056) = 0.0040 m

Page 15: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Lenticular Screen

• Array of cylindrical lenses– Generates autostereo image– Directs 2D images into viewing subzones– Viewer puts one eye in each subzone

Page 16: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 17: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Lenticular Screen

• Horizontal resolution -> one pixel per lenticule

• Vertical resolution -> same as back screen

• N subzones created by N pixels behind each lenticule

Page 18: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Side-Lobes are duplicate sub-zones off to the side of the main centered viewing zone.

Moving out of viewing zone into side-lobes causes pseudoscopic 3D image (right <-> left)

Page 19: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Limitations

• High horizontal resolution required

• Pixel size limits number of views

• Imperfections in lenses focusing abilities– Reduces the directivity– Emerging rays not parallel

• Need to have back screen perfectly aligned with lenticules– Hard because CRTs not flat

Page 20: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

• Can be used with multiple projectors

• Diffusing screen

• High horizontal resolution and large number of views possible

• High bandwidth costs

Page 21: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Integral photography

• Similar to lenticular imaging

• Small spherical lenses instead of vertical cylinders

• Up and down in addition to left and right

• Requires more resolution or 2D array of projectors

Page 22: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Example

• Horizontal resolution– Res of each view = screen width / lenticle

width = horizontal res of back screen / number of views

• Horizontal angular resolution = lenticule width / Dscreen

Page 23: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Depth Resolution

• Finite size of horizontal imaging elements

• Limits resolvable depth levels

Page 24: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 25: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Depth Resolution

• Subzones may overlap– Due to imperfect direction from lenses– Can degrade depth resolution– Since image space quantized depth res not degrade

until blur angle approaches the angle of the viewing subzones

Page 26: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Depth resolution

– To avoid loss of resolution:

– αc is the spread due to min electron beam width / focal length of lenticules

– αd = 2 asin λ(wavelenght) / pitch

subzonedlc 222

Page 27: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 28: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 29: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 30: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 31: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Brightness + Color

• Lenticular screens offer comparatively good brightness to other methods such as parallax barriers.

• Directs only a fraction of the screen, but collects light from a larger area.

• Color can be problem because of CRT phosphor layouts.

Page 32: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.

Example

• Similar to Hamasaki’s using Braun tube– Allows accurate registration of vertical pixel strips– 8 views– 256 x 256 each– 1 mm lenticules– Focal length 2.25 mm– Horizontal pitch .125 mm– Min electron beam size 0.07 mm– Subzones 35 – 40 mm wide at 750 mm distance

Page 33: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.
Page 34: What’s on page 13-25? Tom Butkiewicz. Refresh Rates Flicker from shutter systems Halve refresh rates 2 eyed 120Hz != 1 eyed 60Hz Phosphors 2 Polarized.