A PROTOTYPE MULTI-VIEWER 3D TV DISPLAY

Phil Surman, Ian Sexton,

Richard Bates, Wing Kai Lee

IMAGING AND DISPLAYS RESEARCH GROUP

DE MONTFORT UNIVERSITY, LEICESTER, UK

3D TELEVISION REQUIREMENTS

No Glasses (autostereoscopic)

Must support multiple viewers

Large viewing area

Compact housing size

Utilise readily-available technology

Low(ish cost)

 

Autostereoscopic

Holographic Multiple ImageVolumetric

RealImage

HoloformMulti-view

Binocular

VirtualImage

FixedViewingZones

HeadTracking

 3D DISPLAYTAXONOMY

HOLOGRAPHICA holographic display is one where the image is produced by wavefront reconstruction

The ideal stereoscopic display would produce images in real time that exhibit all the characteristics of the original scene. This would require the reconstructed wavefront to be identical and could only be achieved using holographic techniques. The difficulties of this approach are the huge amounts of computation necessary to calculate the fringe pattern, and the high resolution of the display, which has to be of the order of a wavelength of light (around 0.5 micron).

HOLOGRAPHY

MITQinetiQ

EASLM

OASLM

AOM

Verticalscanner

Imaginglens

Outputlens

Verticaldiffuser

Horizontalscanner

HOLOGRAPHY

Large complex hardware for small image volume

High computational overhead Naturally-lit scenes difficult

Unlikely for next generation TV

Maybe head tracking could be used

Virtual image

Real Image

• Swept volume

• Static volume

VolumetricA volumetric display is one where the image is produced within a volume of space, and the space may be either real or virtual.

VOLUMETRIC

Virtual Image

Static Volume

Swept Volume

VOLUMETRIC: PROS AND CONS

Image transparency.

Difficult capture for video

Non-Lambertian distribution difficult Swept volume not suitable for TV as this needs ‘window’ presentation

• Motion parallax• No accommocation / convergence rivalry

HOLOFORM: Large number of views give smooth motion parallax and hence hologram-like appearance.

MULTI-VIEW: Series of discrete views presented across viewing field – these give motion parallax over limited region.

BINOCULAR: Two views only presented. These may occupy fixed positions or follow viewers’ eye positions using head tracking.

MULTIPLE IMAGE DISPLAYSIn multiple image displays, two or more images are seen across the width of the viewing field.

QinetiQ

HOLOFORM

Cambridge

Holografika

Holoform displays presentcontinuous motion parallax across the viewing field

• Motion parallax Large amounts of information

must be displayed Large image capture camera

In multi-view displays, a series of discrete views are presented across the viewing field.

Multi-view Displays

LENTICULAR PARALLAXBARRIER

VIEWINGZONES

SCREEN

2 4 6 1 3 5 7

1 3 5 7 2 4 6

2 4 6 1 3 5 7

1 3 5 7 2 4 6

X Y

X Y

A display that is so real you can almost touch the objects as they come out of the screen in 3D has been a dream for many years. But no longer claims Philips technology which is combining LCD manufacture, optical screen design and image processing software to deliver second generation 3D consumer technology.

Philips Multiview Display

• Simple construction• Philips is 3D/2D switchable

Viewing area rather limited for TV use Reduced resolution – but only factor of 3 in each direction for Philips display and factor of 2 for Sanyo 4-view.

Multi-view – Pros and Cons

• SINGLE VIEWER, FIXED VIEWING ZONES: Allows only small viewer head movement - < 65mm laterally.

• SINGLE VIEWER, HEADTRACKED: Enables greater freedom of head movement

•MULTI-VIEWER, HEAD TRACKED: The same pair of images are presented to every viewer and large freedom of movement enabled.

BINOCULAR DISPLAYSBinocular, or two-image, displays may be one of three basic types:

Fixed Viewing Zones

Sharp 2D/3D Parallax

Barrier Display

LEFTRIGHT RIGHT LEFT

Lenticular

SeeReal Prism Mask Display

RealityVision HOE Display

Binocular:Single Viewer, Head Tracked

SeeReal Head Tracked Display

• PRISM MASK: SeeReal have produced a head-tracked version.

• HOE: A head-tracked RealityVision display is probably being developed by Samsung, but no definite information is available about this.

• LENTICULAR (i) : Heinrich-Hertz-Institut have produced display that enables lateral head movement.

• LENTICULAR (ii) : Heinrich-Hertz-Institut display developed to also allow for Z-direction.

STEREO IMAGE PAIR ON ONE LCD SCREEN EXIT PUPILS FORMED IN VIEWING FIELD EXIT PUPIL PAIR FOR EACH VIEWER PUPILS FOLLOW VIEWERS EYES BY HEAD TRACKING

Binocular:Multi-user, Head TrackedSingle user methods cannot be developed into multi-user displays.

FIRST PROTOTYPE

TWO-YEAR €6M PROJECT LED BY PHILIPS DMU CARRIED OUT MULTI-USER DISPLAY

WORK ATTEST FINISHED IN MARCH 2004 PROOF-OF-PRINCIPLE PROTOTYPE

DEVELOPED UNDER ATTEST

SCREENA

B

CMULTIPLE EXIT PUPILS

TOP VIEWSVIEWER

EXIT PUPIL PAIR

L

R

Exit Pupils

STEERING ARRAY REPLACES CONVENTIONAL BACKLIGHT ARRAY EFFECTIVELY SERIES OF LENSES AND

LIGHT SOURCES SPACING DETERMINES DISTANCE PROVIDES 2-DIMENSIONAL CONTROL

Exit pupil

Illuminationsources Steering array

lenses

Exit pupil

Illuminationsources

Steering array lenses

Toviewer

Aperture

Driver board

LED array

STEERING ARRAY ELEMENT

Coaxial optical element has no off-axis aberrations.

Light contained within element by total internal reflection.

IMAGE MULTIPLEXING LCDs TOO SLOW FOR TEMPORAL MUX LEFT AND RIGHT IMAGES ON ALTERNATE

LINES HIGH RESOLUTION LCD (1200 X 1600) MUX SCREEN BEHIND LCD

MUXscreen

Steeringarrays

To exit pupils

R

L

Left exit pupil

Right exit pupil

LCD

Demonstrator Array

DEMONSTRATOR TARGETS

VIEWER A

VIEWER B

Viewer positions determined by Polhemus 4-target head tracker

STEERING ARRAY

FOLDING MIRROR SCREEN

ASSY.

Prototype

BRIGHTNESS BANDING CROSSTALK

FIRST PROTOTYPE RESULTS – ISSUES TO BE ADDRESSED:

BRIGHTNESS ARRAY USES LOW DENSITY 3mm LEDs

(ORIGINALLY MADE FOR DEMONSTRATOR)

90 x 3mm WHITE LEDs

LED DRIVERS

LIGHT

BANDING

Apertures

Illuminating surfaces

Refracting surfacesLight to screen

(a) Array element configuration (top view)

(b) Appearance of aperture images

(c) Intensity variation

Distance across array

Relativeintensity

00

X

CIE chromaticity diagram

0.5

0.5

Y

Figure 4. White LED colour variation

0 50 100 150 200 250 0

10

20

30

40

50

60

70

80

90

100

Re

lativ

e In

tens

ity %

Distance / mm DISTANCE (mm)

RE

LA

TIV

E I

NT

EN

SIT

Y (

%)

LCD DIFFRACTION

NEC LCD SUB-PIXEL MICROSTRUCTURE

POINT SPREAD FUNCTION

3 COMPONENTS: 270 µM PIXEL PITCH 90 µM SUB-PIXEL PITCH 15 µM MICROSTRUCTURE

FIRST PROTOTYPE

• USES 1800 x 3mm WHITE LEDs

• PERFORMANCE RELATIVELY POOR, BUT SUFFICIENT FOR PROOF OF PRINCIPLE

• EXIT PUPILS MOVE IN ~ 30 mm INCREMENTS

• EXPERIENCE GAINED USED FOR SECOND PROTOTYPE

DRIVERS

SECOND PROTOTYPE CURRENTLY UNDER CONSTRUCTION

5120 WHITE SURFACE-MOUNT LEDs

I6-ELEMENT LED ARRAYS WITH LENSING

EXIT PUPILS MOVE IN ~ 10 mm INCREMENTS

GLASS OPTICAL ELEMENTS – LESS SCATTER

ANTICIPATE IMAGE WILL STILL BE DIM

CROSSTALK REDUCED BY:

OPERATING LCD IN PORTRAIT ORIENTATION

USING MORE SUITABLE LCD

16-element LED Array Module

WHITE LED& LENS ARRAY

DRIVER CHIP

HEAT SINK

HEAT SINK DRIVER

CHIP

LIGHTLIGHT

MICROLENS ARRAY

SCATTERING REDUCEDAT APERTURE AND

LENS SURFACE

FUTURE RESEARCH

• CONSUMERS WILL DEMAND HANG-ON-WALL – FOLDING NOT SUFFICIENT

• DIFFERENT CONFIGURATION NEEDED

• LEDs MAY NOT MOST SUITABLE SOURCE: Brightness variation Colour variation Insufficient light output Large number of units

• COULD USE ARRAY OF BLUE JUNCTIONS WITH COMMON PHOSPHOR

FOLDING WILL REDUCE SIZE TO CURRENT LARGER REAR PROJECTED SETS

WON’T BE SIZE OF SLIMMER REAR PROJECTED SETS AS FACETED COMPONENTS CAN’T BE USED

DIFFICULT CONSTRUCTION:

SURFACE-SILVERED

HIGH ACCURACY

VISIBILITY OF CORNERS

Bottom layerTop layer

Apertures

Refractingsurfaces

Light toLCD

Illumination Plane

TOP VIEWSEMI-COAXIAL ARRAY

FLAT ILLUMINATION PLANE

ACYLINDRICAL LENS SURFACE

LARGE NUMBER OF INEXPENSIVE MOULDED ELEMENTS

HANG-ON-WALL

ARRAY ELEMENT

HANG-ON-WALL CONFIGURATION

SCREENASSY.

STREERING

ARRAYS

MIRRORS

ILLUMINATION PLANES

VIEWERS

SLMs CAN BE USED (TRIED MONOCHROME LCD BUT TOO DIM)

POSSIBLY USE SLM IN FOURIER TRANSFORM PLANE OF OPTICS FOR GREATER EFFICIENCY

LIGHT COULD BE PIPED OR PROJECTED

EVERY ILLUMINATION PLANE HAS SAME INFORMATION

LEFT

RIGHT

STATIC MUXSCREEN

LCD

REALARRAY

VIRTUAL ARRAY

TEMPORALMUX SCREEN

LCDTemporal Multiplexing

Static Multiplexing

TEMPORAL MUX – (IF FAST LCD NOT AVAILABLE)

2-image Head-tracked Stereo:Advantages

•Minimum amount of information displayed.

•Smallest extra bandwidth required for transmission ~ 10 - 15% (exploits redundancy in stereo pair).

•Simplest image capture – could be single camera pair (but might be better to have an array to enable processing).

A

B

A

B

EYES FOCUS ON PLANE OF SCREEN

EYES CONVERGE ON ‘OBJECT’

L

R

FALSE ROTATION

FOCUS / ACCOMMODATION RIVALRY

NO MOTION PARALLAXIMAGE GEOMETRY DISTORTIONS

2-image Stereo:Limitations

DMU’S APPROACH AIMED AT TV MARKET: i.e. SEVERAL VIEWERS OVER ROOM-SIZED AREA NOT SINGLE-VIEWER OR THEATRE PRESENT STEREO PAIR ONLY: NO MOTION PARALLAX BUT - LEAST AMOUNT OF INFORMATION DISPLAYED IMAGES PLACED IN VIEWING FIELD ONLY AT EYE LOCATIONS SIMPLEST CAPTURE AND TRANSMISSION

HOWEVER, APPROACHES OTHER THAN TWO-IMAGE HEAD TRACKED DISPLAYS MIGHT BE APPROPRIATE, FOR EXAMPLE:• MULTI-VIEW, AS CAN BE VERY SIMPLE TO IMPLEMENT• HOLOFORM, WHERE REDUNDANCY IN IMAGE IS EXPLOITED•VOLUMETRIC WHERE IMAGE IS OPAQUE

THESE TECHNIQUES WILL BE EXPLORED WITHIN THE 3D TV NETWORK OF EXCELLENCE

3D TV NETWORK OF EXCELLENCE

EU FUNDED CONSORTIUM IN FRAMEWORK 6 OF IST PROGRAMME

4-YEAR PROJECT STARTED IN SEPTEMBER 2004

150 RESEARCHERS FROM 19 ORGANISATIONS

LED BY BILKENT UNIVERSITY

HAS STRONG ACADEMIC BIAS

• TC1: 3D SCENE CAPTURE AND SCENE REPRESENTATION

• TC2: 3D TV CODING AND OTHER GENERIC ISSUES

• TC3: TRANSMISSION

• TC4: SIGNAL PROCESSING ISSUES IN 3D TV

• TC5: 3D TV DISPLAY TECHNIQUES

WORK IS COVERED WITHIN 5 TECHNICAL COMMITTEES:

WILL COVER ALL ASPECTS OF 3D (NOT JUST TV)

ROADMAPPING WITH QUESTIONNAIRES AND DELPHI ANALYSIS

CONTACT BETWEEN NETWORKS

COMPLEMENT ADRIA DISPLAYS NETWORK AND NoE

WILL HAVE INFLUENTIAL STEERING GROUP – LOT OF INTEREST

CURRENTLY UNDER EVALUATION - RESUBMIT SEPTEMBER IF UNSUCCESSFUL

3D TELEVISION SPECIFIC SUPPORT ACTION (TESSA)

DMU

3D CONSORTIUM(INTERNATIONAL)

SID RUSSIA& BELARUSCHAPTERS

ASIA PACIFICTECHNOLOGY

NETWORK

PHOTONICSCLUSTER (UK)

ADRIA DISPLAYSNETWORK

SID UKCHAPTER

LE CLUBVISU

(FRANCE)

3D TVNETWORK OFEXCELLENCE

DMU AT HUB OF 3D NETWORKING

‘Specific support actions are intended to support the implementation of FP6, and may also be used to help prepare for future Community research policy activities.’

CONCLUSIONS

THE INTENTION IS FOR 3D TV TO COME TO MARKET WITHIN THE NEXT TEN YEARS.

TIMING IS RIGHT AS LCD AND OTHER ENABLING TECHNOLOGIES ARE RAPIDLY EVOLVING.

TWO-IMAGE HEAD TRACKING PARTICULARLY SUITED FOR 3D TV, BUT OTHER METHODS TO BE CONSIDERED ALSO.