CHAPTER-1

AIMS TO PROJECT 3D TV

Project Aims to Create 3D Television by 2020

Tokyo - Imagine watching a football match on a TV that not only shows the players in three

dimensions but also lets you experience the smells of the stadium and maybe even pat a goal

scorer on the back.

Japan plans to make this futuristic television a commercial reality by 2020as part of a

broad national project that will bring together researchers from the government, technology

companies and academia.

The targeted "virtual reality" television would allow people to view high definition

images in 3D from any angle, in addition to being able to touch and smell the objects being

projected upwards from a screen to the floor.

"Can you imagine hovering over your TV to watch Japan versus Brazil in the finals of

the World Cup as if you are really there?" asked Yoshiaki Takeuchi, development at Japan's

Ministry of Internal Affairs and Communications.

While companies, universities and research institutes around the world have made

some progress on reproducing 3D images suitable for TV, developing the technologies to

create the sensations of touch and smell could prove the most challenging, Takeuchi said in

an interview with Reuters.

Researchers are looking into ultrasound, electric stimulation and wind pressure as

potential technologies for touch.

Such a TV would have a wide range of potential uses. It could be used in home-

shopping programs, allowing viewers to "feel" a handbag before placing their order, or in the

medical industry, enabling doctors to view or even perform simulated surgery on 3D images

of someone's heart.

The future TV is part of a larger national project under which Japan aims to promote

"universal communication," a concept whereby information is shared smoothly and

intelligently regardless of location or language.

[1]

Takeuchi said an open forum covering a broad range of technologies related to

universal communication, such as language translation and advanced Web search techniques,

could be established by the end of this year.

Researchers from several top firms including Matsushita Electric Industrial Co. Ltd.

and Sony Corp. are members of a report on the project last month.

The ministry plans to request a budget of more than 1 billion yen to help fund the project in

the next fiscal year starting in April 2006

[2]

CHAPTER-2

INTRODUCTION

Three-dimensional TV is expected to be the next revolution in the TV history. They

implemented a 3D TV prototype system with real-time acquisition transmission, & 3D

display of dynamic scenes. They developed a distributed scalable architecture to manage the

high computation & bandwidth demands. 3D display shows high-resolution stereoscopic

color images for multiple viewpoints without special glasses. This is first real time end-to-end

3D TV system with enough views & resolution to provide a truly immersive 3D experience.

2.1 Why 3D TV

The evolution of visual media such as cinema and television is one of the major

hallmarks of our modern civilization. In many ways, these visual media now define our

modern life style. Many of us are curious: what is our life style going to be in a few years?

What kind of films and television are we going to see? Although cinema and television both

evolved over decades, there were stages, which, in fact, were once seen as revolutions:

1) at first, films were silent, then sound was added;

2) cinema and television were initially black-and-white, then color was introduced;

3) computer imaging and digital special effects have been the latest major novelty.

So the question is: what is the next revolution in cinema and television going to be?

If we look at these stages precisely, we can notice that all types of visual media have

been evolving closer to the way we see things in real life. Sound, colors and computer

graphics brought a good part of it, but in real life we constantly see objects around us at close

range, we sense their location in space, we see them from different angles as we change

position. This has not been possible in ordinary cinema. Movie images lack true

dimensionality and limit our sense that what we are being seeing is real.

Nearly a century ago, in the 1920s, the great film director Sergei Eisenstein said that

the future of cinematography was the 3d motion pictures. Many other cinema pioneers

thought in the same way. Even the Lumière brothers experimented with three-dimensional

(stereoscopic) images using two films painted in red and blue (or green) colors and projected

simultaneously onto the screen. Viewers saw stereoscopic images through glasses, painted in

the opposite colors. But the resulting image was black-and-white, like in the first feature

stereoscopic film "Power of Love" (1922, USA, Dir. H. Fairhal).

[3]

CHAPTER-3

Basics of 3D TV

Human gains three-dimensional information from variety of cues. Two of the most

important ones are binocular parallax & motion parallax.

3.1 Binocular Parallax

It means for any point you fixate the images on the two eyes must be slightly

different. But the two different image so allow us to perceive a stable visual world. Binocular

parallax r defers to the ability of the eyes to see a solid object and a continuous surface

behind that object even though the eyes see two different views.

3.2 Motion Parallax

It means information at the retina caused by relative movement of objects as the

observer moves to the side (or his head moves sideways). Motion parallax varies depending

on the distance of the observer from objects. The observer's movement also causes occlusion

(covering of one object by another), and as movement changes so too does occlusion. This

can give a powerful cue to the distance of objects from the observer. For example, you are

sitting in the train & trees are going opposite side to you. Wheatstone was able to

scientifically prove the link between parallax & depth perception using a stereoscope- the

world's first three dimensional display device. So, there will be a question in your mind that

what are this depth perception, stereoscopic images & stereoscope. Let's understand these

words.

3.2.1 Depth perception

It is the visual ability to perceive the world in three dimensions. It is a trait common to

many higher animals. Depth perception allows the beholder to accurately gauge the distance

to an object.

The small distance between our eyes gives us stereoscopic depth perception. The

brain combines the two slightly different images into one 3D image. It works most effectively

for distances up to 18 feet. For objects at a greater distance, our brain uses relative size and

motion to determine depth. The ability to distinguish objects in a visual field. Figure 1 shows

the depth perception.

[4]

Fig.3.1 Depth Perception

As shown in the figure, each eye captures its own view and the two separate images

are sent on to the brain for processing. When the two images arrive simultaneously in the

back of the brain, they are united into one picture. The mind combines the two images by

matching up the similarities and adding in the small differences. The small differences

between the two images add up to a big difference in the final picture ! The combined image

is more than the sum of its parts. It is a three-dimensional stereo picture.

The word "stereo" comes from the Greek word "stereos" which means firm or solid.

With stereovision you see an object as solid in three spatial dimensions-width, height and

depth--or x, y and z. It is the added perception of the depth dimension that makes stereovision

so rich and special.

3.2.2 Stereographic Images

It means two pictures taken with a spatial or time separation that are then arranged to

be viewed simultaneously. When so viewed they provide the sense of a three-dimensional

scene using the innate capability of the human visual system to detect three dimensions.

Figure 2 shows the stereographic images.

[5]

Fig.3.2 Stereoscopic Images

As you can see, a stereoscopic image is composed of a right perspective frame and a left

perspective frame - one for each eye.

When your right eye views the right frame and the left frame is viewed by your left

eye, your brain will perceive a true 3D view.

Fig.3.3 Stereoscopes

3.2.3 Stereoscope

It is an optical device for creating stereoscopic (or three dimensional) effects from flat

(two-dimensional) images; D.Brewster first constructed the stereoscope in 1844. It is

provided with lenses, under which two equal images are placed, so that one is viewed with

the right eye and the other with the left. Observed at the same time, the two images merge

[6]

into a single virtual image, which, as a consequence of our binocular vision, appears to be

three-dimensional.

For those wondering what "stereoscopic" is all about, viewing stereoscopic images

gives an enhanced depth perception. This is similar to the depth perception we get in real life,

the same effect IMAX 3D and many computer games now provide.

3.3 Holographic Images

A luminous, 3D, transparent, colored and nonmaterial image appearing out of a 2D

medium, called a hologram. A holographic image cannot be viewed without the proper

lighting. Holographic images can be viewed in virtual space (behind the film plane), in real

space (in front of the film plane), or in both at once. They may be orthoscopic, that is, have

the same appearance of depth and parallax as the original 3D image, or pseudoscopic, in

which the scene depth is inverted. Holographic images do not create a shadow, since they are

non-material. They can only be viewed in.

[7]

CHAPTER-4

OVERVIEW OF THE SYSTEM

3D video usually refers to store animated sequences, whereas 3D TV includes real-

time acquisition, coding & transmission of the dynamic scene. In this seminar we present first

end-to-end 3D TV system with 16 independent high resolution views & auto stereoscopic

display. They have used hardware synchronized cameras to capture multiple perspective

scenes. They have developed a fully distributed architecture with clusters of PCs on the

sender & receiver side. The system is scalable in the number of acquired, transmitted, &

displayed video streams. The system architecture is flexible enough to enable a broad range

of research in 3D TV. This system provides enough viewpoints 8 enough pixels per

viewpoint to produce a believable & immersive 31) experience. In these system there are

following contribution:

1. Distributed architecture

2. Scalability

3. Multiview video rendering

4. High-resolution 3D display

5. Computational alignment for 3D display

4.1 Model Based System

One approach to 3D TV is to acquire multiview video from sparsely arranged cameras

& to use some model of the scene for view interpolation.

Typical scene models are per-pixel depth maps, the visual hull, or a prior model of the

acquired objects, such as human body shapes as shown in the figure 4.

[8]

Fig.4.1 Interpolations

It has been shown that even coarse scene models improve the image quality during view

synthesis. It is possible to achieve very high image quality with two layer image

representation that includes automatically extracted boundary mattes near depth penetration.

The Blue-C system consists of a room-sized environment with real-time capture & spatially

immersive display. All 3D video systems provide the ability to interactively control the

viewpoint, the feature that has been termed free viewpoint video by the MPEG Ad-Hoc

Group on 3D Audio 8 Video (3DAV). Real-time acquisition of scene models for general,

real-world scenes is very difficult. Many systems do not provide real-time end-to end

performance, and if they do they are limited to simple scenes with only a handful of objects.

Using a dense light field representation that does not require a scene model but on the other

hand, dense light field require more storage 8 transmission bandwidth. So, related to this light

field systems is our next topic.

4.2 Light Field System

A light field represents radiance as a function of position & direction in regions of

space free of occludes. The light field describes the amount of light traveling through every

point in 3D space in every possible direction. It varies with the wavelength A, distance x &

the unit vector direction w. In this system, the ultimate goal, which Gavin Miller called the "

hyper display ", is to capture a time varying light field passing through a surface & emitting

the same light field through another surface with minimum delay. Acquisition of dense,

[9]

dynamic light fields has only recently become feasible. Some system uses a bundle of optical

fibers in front of high definition camera to capture multiple views simultaneously. The

problem with the single camera is that the limited resolution of the camera greatly reduces the

number & resolution of the acquired views. Dense array of synchronized cameras will give

high resolution light fields. These cameras are connected with the cluster of PCs. Camera

array consists of up to 128 cameras & special purpose hardware to compress & store all the

video data in real-time. Most light field cameras allow interactive navigation & manipulation

of the dynamic scene. Now, let's move on to the architecture of the 3D TV.

[10]

CHAPTER-5

ARCHITECTURE OF 3D TV

Figure 5 shows the schematic representation of 3D TV system.

Fig.5.1 3D TV System

The whole system consists mainly three blocks:

1. Acquisition

2. Transmission

3. Display Unit

The system consists mostly of commodity components that are readily available

today. Note that the overall architecture of system accommodates different display types.

Let's understand the three blocks one after another.

5.1 Acquisition

The acquisition stage consists of an array of hardware-synchronized cameras. Small

clusters of cameras are connected to the producer PCs. The producers capture live,

uncompressed video streams & encode them using standard MPEG coding. The compressed

video then broadcast on separate channels over a transmission network, which could be

digital cable, satellite TV or the Internet.

[11]

As explain above each camera captures progressive high-definition video in real time.

Generally they are using 16 Basler A101fc color cameras with 1300X1030, 8 bits per pixel

CCD sensors. The question might be arising in your mind that what are CCD image sensors

& MPEG coding?

5.1.1 CCD Image Sensors

Charge coupled device are electronic devices that are capable of transforming a light

pattern (image) into an electric charge pattern (an electronic image). The CCD consists of

several individual elements that have the capability of collecting, storing and transporting

electrical charge from one element to another. This together with the photosensitive

properties of silicon is used to design image sensors. Each photosensitive element will then

represent a picture element (pixel). With semiconductor technologies and design rules,

structures are made that form lines, or matrices of pixels. One or more output amplifiers at

the edge of the chip collect the signals from the CCD. An electronic image can be obtained

by - after having exposed the sensor with a light pattern - applying series of pulses that

transfer the charge of one pixel after another to the output amplifier, line after line. The

output amplifier converts the charge into a voltage. External electronics will transform this

output signal into a form suitable for monitors or frame grabbers. CCDs have extremely low

noise figures. Figure 6 shows CCD sensors.

Fig.5.2 CCD Image Sensor

CCD image sensors can be a color sensor or a monochrome sensor. In a color image

sensor an integral RGB color filter array provides color responsively and separation. A

monochrome image sensor senses only in black and white. An important environmental

parameter to consider is the operating temperature.

[12]

5.1.2 MPEG-2 Encoding

MPEG-2 is an extension of the MPEG-1 international standard for digital

compression of audio and video signals. MPEG-2 is directed at broadcast formats at higher

data rates; it provides extra algorithmic 'tools' for efficiently coding interlaced video, supports

a wide range of bit rates and provides for multichannel surround sound coding. MPEG- 2

aims to be a generic video coding system supporting a diverse range of applications.

Different algorithmic 'tools', developed for many applications, have been integrated into the

full standard. To implement all the features of the standard in all decoders is unnecessarily

complex and a waste of bandwidth, so a small number of subsets of the full standard, known

as profiles and levels, have been defined. A profile is a subset of algorithmic tools and a level

identifies a set of constraints on parameter values (such as picture size and bit rate). A

decoder, which supports a particular profile and level, is only required to support the

corresponding subset of the full standard and set of parameter constraints.

Now, the cameras are connected by IEEE-1394 High Performance Serial Bus to the

producer PCs. The maximum transmitted frame rate at full resolution is 12 frames per

seconds. Two cameras each are connected to one of the eight producer PCs. All PCs in this

prototype have 3 GHz Pentium 4 Processors, 2 GB of RAM, & run Windows XP.

They chose the Basler cameras primarily because it has an external trigger that allows

for complete control over the video timing. They have built a PCI card with custom

programmable logic device (CPLD) that generates the synchronization signal for all the

cameras. So, what is PCI card?

5.1.3 PCI Card

The power and speed of computer components has increased at a steady rate since

desktop computers were first developed decades ago. Software makers create new

applications capable of utilizing the latest advances in processor speed and hard drive

capacity, while hardware makers' rush to improve components and design new technologies

to keep up with the demands of high end software.

[13]

Fig.5.3 PCI Card

There's one element, however, that often escapes notice - the bus. Essentially, a bus is

a channel or path between the components in a computer. Having a high-speed bus is as

important as having a good transmission in a car. If you have a 700-horsepower engine

combined with a cheap transmission, you can't get all that power to the road. There are many

different types of buses. In this article, you will learn about some of those buses. We will

concentrate on the bus known as the Peripheral Component Interconnect (PCI). We'll talk

about what PCI is, how it operates and how it is used, and we'll look into the future of bus

technology.

All 16 cameras are individually connected to the card, which is plugged into the one

of the producer PCs. Although it is possible to use software synchronization, they consider

precise hardware synchronization essential for dynamic scenes. Note that the price of the

acquisition cameras can be high, since they will be mostly used in TV studios.

They arranged the 16 cameras in regularly spaced linear array. See the figure 8.

Fig.5.4 Arrays of 16 Cameras

[14]

The optical axis of each camera is roughly perpendicular to a common camera plane.

It is impossible to align multiple cameras precisely, so they use standard calibration

procedures to determine the intrinsic & extrinsic camera parameters. In general, the cameras

can be arranged arbitrarily because they are using light field rendering in the consumer to

synchronize new views. A densely spaced array proved the best light fields capture, but high-

quality reconstruction filters could be used if the light field is under sampled.

5.2 Transmission

Transmitting 16 uncompressed video streams with 1300X1030 resolution & 24 bits

per pixel at 30 frames per seconds requires 14.4 Gblsec bandwidth, which is well beyond

current broadcast capabilities. For compression & transmission o1 dynamic muitiview video

data there are two basic design choices. Either the data from multiple cameras is compressed

using spatial or spatio-temporal encoding, or each video stream is compressed individually

using temporal encoding. The first option offers higher compression, since there is a lot of

coherence between the views. However, it requires that a centralized processor compress

multiple video streams. This compression-hub architecture is not scalable, since the addition

of more views will eventually overwhelm the internal bandwidth of the encoder. So, they

decided to use temporal encoding of individual video stream on distributed processors.

This strategy has other advantages. Existing broadband protocols & compression

standards do not need to be changed for immediate real world 3D TV experiments. This

system can plug into today's digital TV broadcast infrastructure & co-exist in perfect

harmony with 2D TV.

There did not have access to digital broadcast equipment, they implemented the

modified architecture as shown in figure 9.

[15]

Fig.5.5 Modified System

Eight producer PCs are connected by gigabit Ethernet to eight consumers PCs. Video

stream at full camera resolution (1300*103D) are encoded with MPEG-2 & immediately

decoded on the producer PCs. This essentially corresponds to a broadband network with

infinite bandwidth & almost zeros delay. The gigabit Ethernet provides all-to-all connectivity

between decoders & consumers, which is important for distributed rendering & display

implementation. So, what is gigabit Ethernet? '

5.2.1 Gigabit Ethernet

It a transmission technology, enables Super Net to deliver enhanced network

performance. Gigabit Ethernet is a high speed form of Ethernet (the most widely installed

LAN technology), that can provide data transfer rates of about 1 gigabit per second (Gbps).

Gigabit Ethernet provides the capacity for server interconnection, campus backbone

architecture and the next generation of super user workstations with a seamless upgrade path

from existing Ethernet implementations.

5.3 Decoder & Consumer Processing

The receiver side is responsible for generating the appropriate images to be displayed.

The system needs to be able to provide all possible views to the end users at every instance.

The decoder receives a compressed video stream, decode it, and store the current

[16]

uncompressed source frame in a buffer as shown in figure 10. Each consumer has virtual

video buffer (VVD) with data from all current source frames. (I.e., all acquired views at a

particular time instance).

Fig.5.6 Block Diagram of Decoder and Consumer processing

The consumer then generates a complete output image by processing image pixels

from multiple frames in the VVB. Due to the bandwidth 8 processing limitations it would be

impossible for each consumer to receive the complete source of frames from all the decoders.

This would also limit the scalability of the system.

Here is one-to-one mapping between cameras & projectors. But it is not very flexible.

For example, the cameras need to be equally spaced, which is hard to achieve in practice.

Moreover, this method cannot handle the case when the number of cameras & projectors is

not same.

Another, more flexible approach is to use image-based rendering to synchronize

views at the correct virtual camera positions. They are using unstructured lurnigraph

rendering on the consumer side. They choose the plane that is roughly in the center of the

depth of field. The virtual viewpoints for the projected images are chosen at even spacing.

Now focus on the processing for one particular consumer, i.e., one particular view. For each

pixel o (u, v) in the output image, the display controller can determine the view number v&

the position (x, y) of each source pixel s (v, x, y) that contributes to it.

To generate output views from incoming video streams, each output pixel is a linear

combination of k source pixels:

0 (u, v) Σ wts (v, x, y) ............ (1)

[17]

The blending weights w can be pre-computed by the controller based on the virtual

view information. The controller sends the position (x, y) of the k source pixels to each

decoder v for pixel selection. The index c of the requesting consumer is sent to the decoder

for pixel routing from decoders to the consumer. Optionally, multiple pixels can be buffered

in to the decoder for pixel block compression before being sent over the network. The

consumer decompresses the pixel blocks & stores each pixel in VVB number v at position (x,

y). Each output pixel requires from k source frames. That means that the maximum

bandwidth on the network to the VVB is k times the size of the output image times the

number of frames per second (fps). This can be substantially reduced if pixel block

compression is used, at the expense of more processing. So to provide scalability it is

important that this bandwidth is independent of the total number of the transmitted views. .

The processing requirements in the consumer are extremely simple. It needs to compute

equation (1) for each output pixel. The weights are pre computed & stored in a lookup table.

The memory requirements are k times the size of the output image. Assuming simple pixel

block compression, consumers can easily be implemented in hardware. That means decoders,

networks, & consumers could be combined on the one printed circuit board. Let's move on to

the different types of display.

[18]

CHAPTER-6

MULTIVIEW AUTO STEREOSCOPIC DISPLAY

6.1 Holographic Displays

It is widely acknowledged that Dennis Gabor invented the hologram in 1948. he was

working on an electron microscope. He coined the word and received a Nobel Prize for

inventing holography in 1971. The holographic image is true three-dimensional: it can be

viewed in different angles without glasses. This innovation could be a new revolution – a new

era of holographic cinema and of holographic media in whole.

Holographic techniques were first applied to image display by Leith & Upatnieks in 1962.

In holographic reproduction, interference fringes on the holographic surface to reconstruct the

light wave front of the original object diffract light from illumination source. A hologram

displays a continuous analog field has long been considered the “holy grail “of 3D TV. Most

recent device, the Mark-2 Holographic Video Display, uses acousto-optic modulators, beam

splitters, moving mirrors & lenses to create interactive holograms. In more recent systems,

moving parts have been eliminated by replacing the acousto-optic modulators with LCD,

focused light arrays, and optically addressed spatial modulators, digital micro mirror devices.

Figure shows the holographic image.

Fig.6.1 Holographic Image

[19]

All current holo-video devices use single-color laser light. To reduce the amount of

display data they provide only horizontal parallax. The display hardware is very large in

relation to size of the image. So cannot be done in real-time.

6.2 Holographic Movies

We have developed the world's first holographic equipment with the capability of

projecting genuine 3-dimensional holographic films as well as holographic slides and real

objects – for the multiple viewers simultaneously. Our Holographic Technology was

primarily designed for cinema. However it has many uses in advertising and show business as

well.

At the same time we have developed a new 3d digital image processing and projecting

technology. It can be used for creation the modern 3d digital movie theaters and for the

computer modeling of 3d virtual realities as well. On the same principle we have already

tested a system 3d color TV. In all cases audience can see colorful 3-d inconvenient

accessories.

Developed in the Holographic Laboratories of Professor Victor Komar (NIKFI), these

technologies have received worldwide recognition, including an Oscar for Technical

Achievement in Hollywood, a Nika Film Award in Moscow, endorsement from MIT's Media

Lab and many others.

On this website you can find general information about our technology, projects, brief

history of 3d and holographic cinema, investment opportunities and sales. For more specific

questions please check FAQ section on the ENQUIRE page. You can also send us a message

via email: the addresses are on the CONTACT page. We have developed the world's first

holographic equipment the genuine 3-dimensional holographic films as well as holographic

slides and real objects – for the multiple viewers. Our Holographic Technology was primarily

designed for cinema. However it has many uses in advertising and show business as well.

6.2.1 Volumetric Displays

It use a medium to fill or scan a three-dimensional space & individually address &

illuminate small voxels. However, volumetric systems produce transparent images that do not

provide a fully convincing three dimensional experience. Furthermore, they cannot correctly

reproduce the light field of a natural scene because of

[20]

their limited color reproduction & lack of occlusions. The design of large size volumetric

displays also poses some difficult obstacles.

6.2.2 Parallax Displays

Parallax displays emit spatially varying directional light. Much of the early 3D

display research focused on improvement to Wheat stone's stereoscope. In 1903, F.Ives used

a plate with vertical slits as a barrier over an image with alternating strips of left-eye/right-

eye images. The resulting device is called a parallax stereogram. To extend the limited

viewing angle 8 restricted viewing position of stereogram, Kanolt & H.Ives used narrower

slits & smaller pitch between the alternating image strips. These multiview images are called

parallax panorama grams.

Stereogram & panorama grams provide only horizontal parallax. Lippmann proposed

using an array of spherical lenses instead of slits. This is frequently called a 'fly's eye" lens

sheet, & resulting image is called integral photograph. An integral is a true planar light field

with directionally varying radiance per pixel. Integral sacrifice significant spatial resolution

in both dimensions to gain full parallax. Researchers in the 1930s introduced the lenticular

sheet, a line of array of narrow cylindrical lenses called Isnticules. Lenticular images found

widespread use for advertising, CD covers, & postcards. To improve the native resolution of

the display, H.Ives invented the multi-projector lenticular display in 1931. He painted the

back of a lenticular sheet with diffuse paint & used it as a projection surface for 39 slide

projectors. Finally high output resolution, the large number of views & the large physical

dimensions of or display leads to a very immersive 3D display. Other research in parallax

displays includes time multiplexed 8 tracking-bass systems. In time multiplexing, multiple

views are projected at different time instances using a sliding window or LCD shutter. This

inherently reduces the frame rate of the display & may lead to noticeable flickering. Head-

tracking designs are mostly used to display stereo images, although it could also be used to

introduce some vertical parallax in multiview lenticular displays. Today's commercial auto

stereoscopic displays use variations of parallax barriers or lenticular sheets placed on the top

of LCD or plasma screens. Parallax barriers generally reduce some of the brightness &

sharpness of the image. Here, this projector based 3D display currently has a native resolution

of 12 million pixels.

[21]

Fig.6.2 Images of a scene from the viewer side of the display (top row) and as seen from some of the cameras (bottom row).

6.2.3 Multi Projector

Displays offer very high resolution, flexibility, excellent cost performance, scalability,

& large-format images. Graphics rendering for multiprojector systems can be efficiently

parallelized on clusters of PCs using, for example, the Chromium API. Projectors also

provide the necessary flexibility to adapt to non-planar display geometries. Precise manual

alignment of the projector array is tedious 8 becomes downright impossible for more than a

handful of projectors or non-planar screens. Some systems use cameras in the loop to

automatically compute relative projectors poses for automatic alignment. Here they will use

static camera for automatic image alignment & brightness adjustments of the projectors.

[22]

CHAPTER-7

3D DISPLAY

This is a brief explanation that we hope sorts out some of the confusion about the many

3D display options that are available today. We'll tell you how they work, and what the

relative tradeoffs of each technique are. Those of you that are just interested in comparing

different Liquid Crystal Shutter glasses techniques can skip to the section at the end.

Of course, we are always happy to answer your questions personally, and point you to other

leading experts in the field.

Figure shows a diagram of the multi-projector 3D displays with lenticular sheets.

Fig.7.1 Projection-type lenticular 3D displays

They use 16 NEC LT-170 projectors with 1024'768 native output resolution. This is

less that the resolution of acquired & transmitted video, which has 1300'1030 pixels.

However, HDTV projectors are much more expensive than commodity projectors.

Commodity projector is a compact form factor. Out of eight consumer PCs one is dedicated

as the controller. The consumers are identical to the producers except for a dual-output

graphics card that is connected to two projectors. The graphic card is used only as an output

device.

For real-projection system as shown in the figure, two lenticular sheets are mounted

back-to-back with optical diffuser material in the center. The front projection system uses

only one lenticular sheet with a retro reflective front projection screen material from flexible

fabric mounted on the back. Photographs show the rear and front projection.

[23]

Fig.7.2 Rear Projection and Front Projection

The projection-side lenticular sheet of the rear-projection display acts as a light

multiplexer, focusing the projected light as thin vertical stripes onto the diffuser. Close up of

the lenticular sheet is shown in the figure 6. Considering each lenticel to be an ideal

Pinhole camera, the stripes capture the view-dependent radiance of a three-

dimensional light field. The viewer side lenticular sheet acts as a light de-multiplexer &

projects the view-dependent radiance back to the viewer. The single lenticular sheet of the

front-projection screen both multiplexes & demultiplexes the light.

The two key parameters of lenticular sheets are the field-of-view (FOV) & the

number of lenticules per inch (LPI). Here it is used 72" ' 48" lenticular sheets with 30 degrees

FOV & 15 LPI. The optical design of the lenticules is optimized for multiview 3D display.

The number of viewing zones of a lenticular display is related to its FOV. For example, if the

FOV is 30 degrees, leading to 180/30 = 6 viewing zones.

7.1 3D TV for 21st Century

Interest in 3D has never been greater. The amount of research and development on 3D

photographic, motion picture and television systems is staggering. Over 1000 patent

applications have been filed in these areas in the last ten years. There are also hundreds of

technical papers and many unpublished projects.

I have worked with numerous systems for 3D video and 3D graphics over the last 20

years and have years developed and marketed many products. In order to give some historical

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perspective I’ll start with an account of my 1985 visit to Exposition 85 in Tsukuba, Japan, I

spent a month in Japan visiting with 3D researchers and attending the many 3D exhibits at the

Tsukuba Science Exposition. The exposition was one of the major film and video events of

the century, with a good chunk of its 2 1/2 billion dollar cost devoted to state of the art

audiovisual systems in more than 25 pavilions. There was the world’s largest IMAX screen,

Cinema-U (a Japanese version of IMAX), OMNIMAX (a dome projection version of IMAX

using fisheye lenses) in 3D, numerous 5, 8 and 10 perforation 70mm systems - several with

fisheye lens projection onto domes and one in 3D, single, double and triple 8 perforation

35mm systems, live high definition (1125 line) TV viewed on HDTV sets and HDTV video

projectors (and played on HDTV video discs and VTR’s), and giant outdoor video screens

culminating in Sony’s 30 meter diagonal Jumbotron (also presented in 3D). Included in the

3D feast at the exposition were four 3D movie systems, two 3DTV systems (one without

glasses), a 3D slide show, a Pulfrich demonstration (synthetic 3D created by a dark filter in

front of one eye), about 100 holograms of every type, size and quality (the Russian’s were

best), and 3D slide sets, lenticular prints and embossed holograms for purchase. Most of the

technology, from a robot that read music and played the piano to the world’s largest tomato

plant, was developed in Japan in the two years before the exposition, but most of the 3D

hardware and software was the result of collaboration between California and Japan. It was

the chance of a lifetime to compare practically all of the state of the art 2D and 3D motion

picture and video systems, tweaked to perfection and running 12 hours a day, seven days a

week. After describing the systems at Tsukuba, I will survey some of the recent work

elsewhere in the world and suggest likely developments during the next decade.

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CHAPTER-8

CONCLUSION

Most of the key ideas for 3D TV systems presented in this paper have been known for

decade, such as lenticular screens, multi projector 3D displays, and camera array for

acquisition. This system is the first to provide enough view points and enough pixels per view

points to produce an immersive and convincing 3D experience. Another area of future

research is to improve the optical characteristic of the 3D display computationally. This

concept is computational display. Another area of future research is precise color

reproduction of natural scenes on multiview display.

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