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					                                                                                                in focus


3D TV beginners
start here
The Deputy Technical Director of the EBU, David Wood examines the
excitement surrounding 3D TV technology. He provides a look at the
background of 3D production and puts forth that if ever 3D TV had a chance
of succeeding, the time is now.

A Hollywood moviemaker, in the flush            reduce the potential for eyestrain, though      problems to overcome too. Today’s 3D
of box office success, claimed that 3D          probably not eliminate it. Furthermore, 3D      will be a subset of natural vision, which
(cinema) stands for ‘Dollars, Dollars, and      works better the more definition there is in    provides some, but not all, of its elements.
more Dollars’. What could it stand for in       the picture, so, in this age of HD, it has a    Everything – production, delivery, and
television in Europe? Could it be ‘Dilemma’     head start.                                     display must be done carefully and
(three times)? - or would it be more like 3x    What is important now for those in              purposefully in 3D TV, to reduce the
‘Do it now!’. That is the enigma for 2009       broadcasting is to understand how 3D TV         propensity for eyestrain. Though it may
and 2010.                                       works, what it can do, and what making          seem simple, in fact there is no place here
There is no doubt that 3D TV has a great        a test or starting a service could mean.        for ‘lash ups’.
‘wow’ factor when you see it first time.        For sure, if your senior management have        There are considered to be three
Many people love it – particularly the          not already asked you what the company          generations of 3D TV which will
young. But it is a risky venture. It is not     should do about 3D TV, they soon will.          progressively come into play in the
HDTV, which is certain to be the future         This article is intended to give you at least   decades ahead.
of television. 3D comes with a history.         a summary, which should help you in your        These are:
3D cinema has emerged, flourished, and          decision making.                                1st Generation 3D TV. This category of
faded just as quickly, in cycles of ominous     In getting to grips with 3D TV, it is           system is practical today, and could be
regularity. Could it be just a fashion for TV                                                   broadcast. It is essentially the combination
also, which will evaporate? Will the public                                                     of left and right eye pictures. The viewer
tire of wearing glasses, and having axes                                                        needs glasses, and the left and right
thrown at them? On the small screen, will                                                       picture are ‘fused’ by the brain into a
there be more to it than a fairground show?                                                     picture with depth - provided there are no
3D production costs in Hollywood are said                                                       more than allowed differences between
to be about double those for 2D, so this                                                        the left and right pictures.
has got to be very popular. 3D production                                                       2nd Generation 3D TV. These systems
grammar can be quite restrictive. Looking                                                       record a large number of pairs of signals,
to Hollywood, there the current rule of                                                         and usually present them on a display
thumb is that for 2D versions of 3D movies,                                                     that does not need glasses (auto-
about one third of the material can used as                                                     stereoscopic). There are limitations on
it is, one third has to be adjusted, and one                                                    resolution and viewing position with
third can’t be used. The best produced 3D                                                       today’s technical systems, but they may
production is going to be different to the                                                      eventually become practical consumer
best 2D production of the same event or         Fig 1. The two Panasonic cameras are            electronics.
story. Content compatibility is an issue.       mounted side by side on a cross-bar rig in      3rd Generation 3D TV. Here we record
The public too will be in for expense.          this shot taken at Broadcast Asia in June       the entire light field or object wave. No
The higher quality systems will need a          2009. The two HD cameras provide HD-            eyestrain. Pictures look great. We are
new TV display, though possibly not a           SDI outputs.                                    probably 30-50 years away from such
new set-top box. However good 3D is,                                                            systems becoming practical.
will the recession put a brake on sales?        important to understand what it is not -        The 3D TV we speak of today is usually
These are the risks, but having said that,      despite the hype. It is not natural vision      1st Generation - based on two camera
we should also recognise that if ever 3D        as we see it everyday. To provide that we       images, which are shot, edited, encoded
TV had a chance of succeeding, it is now.       would need the many gigabits needed to          and delivered to the viewer, who will
The great bugbear of 3D in the past was         record and transmit a full optical ‘wave-       have some arrangement (usually special
eyestrain. By using digital post processing     front’ (technically the ‘object wave’).         glasses) to ensure that the left and right
in production, and in the receiver, we can      There would be many more technical              eye signals get to the right home (eye).




06 tech-i | http://tech.ebu.ch | september 2009
3D Production                                    a lot of options, and all of them would
3D TV is shot with a rig which may be            work. The question is whether 3D TV
                                                 can possibly be a success unless we all
                                                                                                       when did it start?
like that in Fig 1. There are many rules to
be applied to production grammar in 3D,          converge onto one system. This area is
including the use of wide angle lenses,          to some extent a ‘standard’s wild west’.
small apertures, carefully chosen ‘lens to       The options for transmitting 3D TV come
first object distance’, and limited depth        down to the following.
range in the shot. These are (of course)         1. Send a COLOUR ANAGLYPH which is
to make nice looking 3D which exploits              a composite of the HDTV left and right
the depth facility, but also to minimise            matrixed luminance pictures, coloured
eyestrain. There is an art in 3D production         Red and Blue/Green, in a single picture.
grammar. It is far from just putting two            This method has limitations in colour
cameras next to each other – though that            fidelity and resolution, but does not need
is where you start.                                 any new infrastructure.
The camera rigs can be arranged to allow         2. Sent TWO HDTV PICTURES left, right:               The first live 3D television broadcasting
the inter-lens spacing to be varied, and the        i.e. a simulcast. This is the high quality/       took place 27 years ago in February
lens toe-in (the ‘vergence’) to be adjusted.        bit rate hungry solution.                         1982 from Hamburg by EBU Member,
There are different views about the use          3. Send TWO ‘HDTV’ PICTURES BUT
                                                                                                      ARD, to the German public. Between
of ‘toe-in’, with electronic processing. It is     ARRANGED TO LOOK LIKE ONE
possible to keep the cameras pointing              HDTV FRAME. This can be done by                    six and seven million anaglyph glasses
directly forward and electronically ‘point’        a) assembling left and right as over and           were sold to the German public for
the camera via frame processing.                   under anamorphic, b) by arranging them
                                                                                                      the occasion. EBU Sub-group V1
When the material is shot, there is more to        as side by side anamorphic, c) by using
                                                   what is called offset subsampling (one             was studying 3D TV at the time, for
do. The left and right pictures need to be
processed for correct geometry alignment,          sample left, then one sample right, and            which David Wood was the Secretary.
and to ensure that the depth position of the       so on), or d) assemble left and right on           The ARD programme was produced
key objects in the shot is good. One reason        alternate lines. There is a compromise
                                                                                                      by Hans Herbst, a pioneer of new
to adjust this is to ensure that when there        with this system in quality and bandwidth.
is a scene cut the main objects do not jump        If one of these systems is used, there is          technology in German broadcasting,
wildly in depth position – this will really        a loss of resolution in either the vertical,       and much of the technology was
start the eyestrain bells ringing. There           horizontal, or diagonal planes. But the            developed by the IRT in Munich.
are some systems available for 3D post             results will not be as bad as you may
                                                                                                      This programme was the first of
production, such as the Quantel ‘Pablo’.           think, because the stereopsis process in
If you visit such companies, they will take        the brain effectively lays the left signal         a number of 3D TV broadcasts in
you on a tour of what their equipment              on top of the right signal, so what you            Germany and France. The basic
does.                                              see is a sum of them. In theory at least,
                                                                                                      principles of a left and right eye picture
3D Delivery                                        it would also be possible to complement
                                                   the system with additional resolution later        were the same as those used today,
Once the 3D programme is assembled,
it needs to be delivered to the viewer.            if it was valuable, using the MPEG SVC             though registration of images and picture
As you might expect, laboratories and              system or similar.                                 quality has been improved by today’s
manufacturers all over the world have            4. Send ONE HDTV PICTURE plus
                                                                                                      digital technology. The first 3D movie
come up with proposals for this, and many           something which allows the two left and
have made working systems. There are                right pictures to be reconstructed in       8     was made in 1922.




                                                                                              tech-i | http://tech.ebu.ch | september 2009 07
                                                                                             in focus

                                                                                             transmission format which will work
                                                                                             with either b or c displays, to encourage
                                                                                             competition for quality, features, and price.
                                                                                             3D TV Standards
                                                                                             Lots of standards groups are ‘in the act’.
                                                                                              ITU-R SG6, the home of Rec. 601. and
                                                                                             Rec. 709. has been working over the past
                                                                                             year assembling information. It’s due to
                                                                                             meet again in October 2009.
                                                                                             The DVB Project is just about to launch
                                                                                             work in its Commercial Module on
                                                                                             requirements for 3D TV.
                                                                                             The SMPTE has produced a report on
                                                                                             scenarios and requirements, and plans
                                                                                             to go further.
                                                                                             The ISO/IEC JTC1 MPEG group
                                                                                             has developed the standards for
                                                                                             ‘2D+something’ compression.
                                                                                             The Blu-ray Consortium has proposals in
                                                                                             discussion, as has the DVD Consortium.
                                                                                             There are methods also used on the
                                                                                             Open Internet.
                                                                                             Where do we go from here? Will there be
                                                                                             a grand reconciliation? Is there a role for
                                                                                             the EBU to play?
                                                                                             Closing Thoughts
                                                                                             Several things are clear.
                                                                                             The higher the quality of the pictures, the
                                            7    the receiver – a difference signal , or a   better is the 3D TV. This is not the place for
                                               ‘depth map’.                                  loss of resolution or compression artefacts.
                                            Each of these methods has advantages and         This must be factored into plans.
                                            disadvantages – and proponents.                  All 3D TV systems have the potential to
                                            3D Displays                                      cause eyestrain. It can be minimised only if
                                            The options for 3D TV displays fall into         we pay attention to detail all the way along
                                            five groups.                                     the production and delivery chain. But don’t
                                            a. Normal colour TV displays. This can be        expect miracles. Do not expect the viewer
                                               used with colour anaglyph transmission,       to watch 3D TV for very long continuous
                                               given the user has the red green/blue         periods, unless he is a seasoned 3D TV
                                               glasses needed.                               viewer with eyes accustomed to the optical
                                            b. New displays with active shutter glasses.     gymnastics needed. Think in terms of an
                                               left and right pictures are shown             hour or two at most.
As you might expect,                           alternately with a 100/120Hz display          3D TV can have a lot of impact, but
laboratories and                               rate. Shutter glasses open/close in sync.     it is not true complete natural vision.
                                                                                             There are limitations.
manufacturers all over the                     controlled by an IR transmitter in the
                                                                                             The most critical issue today is deciding on
                                               display.
world have come up with                     c. New displays with passive polarised           a unique transmission format for left and
                                                                                             right signals, which operate in an HDTV
proposals, and many have                       glasses. left and right shown alternately
                                                                                             environment.
                                               with switched polarised screen cover and
made working systems.                          a 100Hz/120Hz display rate, or left and       Most of all, today you need to know how
There are a lot of options,                    right on alternate lines.                     3D TV works - so quiz the EBU, the
                                            d. Anamorphic displays. No glasses               manufacturers, or try it yourself. The 3D
and all of them would work.                    needed, but other limitations. One of the     TV train is rolling, and you need to work
The question is whether                        major developing companies, Philips, has      out the cost of a ticket on it. If 3D cinema,
                                                                                             packaged media, Internet, and broadcast
3D TV can possibly be                          withdrawn from this area. Most suited to
                                                                                             services from private broadcasters, are
                                               2nd generation 3D TV.
a success unless we all                     Each of these also has its own advantages        successful then the ‘3D’ in Europe might
converge onto one system.                   and disadvantages. Current opinion in the        turn out to stand for 3x ‘Demand (from the
                                            broadcasting community is that options b         public)’.
                                            and c are the best for broadcasting today.
                                            It would be possible to define a standard




08 tech-i | http://tech.ebu.ch | september 2009

				
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