This is not a full technology report on 3D because there is still so much development going on and standards yet to be formulated. This report covers observation of 3D demos at CEDIA and what I have been told or have read about 3D that should remain true regardless of future standards.
3D Display Technology: Active LCD Shutter System
During the Sony press conference at CEDIA we were told their goal has been, and continues to be, market innovation, and that 3D HDTV was their next project. Sony had a flat panel LCD running a 3D Demo in their booth. Panasonic brought their 3D truck to the show providing a 3D demo using their 103” plasma. I asked the rep in the truck about the Sony statement. It received a chuckle along with a short check list of Panasonics deep involvement from Hollywood to television broadcasters. Panasonic claimed that 3D video and film cameras have been fully developed and stand ready to provide native 3D content. During the presentation Panasonic stated their goal of bringing 3D content to the home, not only with Blu-ray but also via broadcast DTV and they were working on that DTV specification. Mitsubishi was providing a demo with their 65” laser-driven LaserVue rear projection DLP. Digital Projection provided a 3D demo via their Titan 3D projector along with their Intelligent Lens Memory system providing cinemascope capability via zoom/focus rather than anamorphic lens on a 2.35 screen in the neighborhood of 240 inches. These demos were all based on stereoscopic technology using the active LCD shutter glasses. This requires batteries for the glasses along with an IR transmitter from the display or 3D source to activate and synchronize them to the video. Basically the LCD for each eye is turned on and off at 120Hz for 60 frames, blocking light or allowing light to pass through, creating stereoscopic vision when synchronized with the video.
Shane Sturgeon, my son Alexander, and I all tested the active LCD shutter system coming to similar conclusions; there was a tendency for flicker and an intermittent fuzzy loss of focus for most of the material with each demo. The Panasonic demo noted that their system was designed to recreate the full aspect of vision by allowing your eyes to naturally change focus as you go from close objects to distant objects in the image. Nonetheless, my son and I found the close objects to lose focus. My son felt some of the objects appeared flat. Shane stated that all of the “Active 3D” demos were quite hard on the eyes and that one even left him with a mild headache afterwards.
In all cases the active LCD shutter glasses significantly reduce light output of the display (each eye is now seeing an image half the time) along with changing the color temperature. They also have some weight to them. This color issue was most noticeable at the Mitsubishi demo. Without glasses the color temp was pushed predominantly blue with some red. The Digital Projection demo had the least amount of color error. In all demos I could see the white balance change with and without glasses. In the case of Mitsubishi, and then Panasonic, the glasses compensated for the naked-eye color response toning down the blue and red for a more natural color temperature. If 3D makes it into the market I smell another calibration spec coming down the line to compensate for this along with some control or feature for switching between 2D and 3D display color temp settings. This could include different color decoding alignments too. Yet with that statement I am getting way ahead of what I do not know! The drop in light output though is significant and disconcerting, being the most problematic with front projectors driving screens that are too large. This always has been, and continues to be, a common problem in the home theater market with most having just enough light horsepower to squeak by. The glasses can easily create a dim image with these products even when the proper screen size and gain was selected. On the other end of the spectrum, you have very bright LCD flat panel technology, with which some dimming might even be welcomed!
3D Display Technology: Passive Polarization System
The active LCD shutter system has competition, supported by JVC and LG as used by Hollywood at your local cinemaplex, in the form of significantly less expensive non-active light weight glasses using polarizing filters. One eye is polarized vertically and the other horizontally requiring a display capable of polarization to create stereoscopic vision. So far this has been the predominant method used by Hollywood and IMAX. On the convention floor JVC had a very small area (directing you to their special rooms at the Omni Hotel) with 3D computer animation running on their 3D X-pol GD-463G10 1080p LCD display. While the 3D experience was impressive the resolution dropped in half, clearly visible as the old fashioned vertical scan lines (the black horizontal spaces in between) from our analog NTSC television system of yesteryear. At the Omni Hotel was another 3D demo using a 2D to 3D converter product connected to another GD-463G10 LCD. The conversion had the appearance of a diorama with flat 2D cutouts along with that half resolution response chock full of scan lines.
We all agreed that we preferred the passive polarizing system. It had none of the negative attributes of the active system, and for display characteristics the passive system appeared to have no effect on color temperature and far less drop in light output. Unfortunately, the half vertical 3D resolution was the down fall! This is caused by the X-pol passive polarizing sheet that creates two polarized images for the glasses by separating each vertical line of pixels yielding an interlaced 1920x540 lines for one eye and 1920x540 lines for the other. The only passive polarizing solution is to use rectangular pixels and double the pixel matrix vertically to 2160 or double both for 3840x2160. An active polarizing sheet would allow X-pol to use a standard 1920x1080 pixel matrix and is under development (although I am hard pressed to find where I heard this). Either way, the X-pol display system comes with a manufacturing disadvantage due to the extra costs required that the active shutter system eliminates for any display technology. On the other hand the passive glasses will be dirt cheap compared to the current $200 each for active glasses. For a family of three, that adds $600 to the 3D at home bill providing a more competitive stance for X-pol.
Panasonic stated at CEDIA their intention to bring stereoscopic 3D to the market in the next 1-2 years. Content will come from Blu-ray 3D first, followed by broadcast DTV at a later date. Blu-ray is easy enough to implement (expect 3D players by early to mid 2010) and will be the reference standard for full resolution 3D content but what about DTV? There are a variety of methods and any of them require a simple change in encoding specs that will allow the 3D spatial content data to be included in the transmission making 3D fully compatible with our current 2D HD system. It is clear and evident that broadcast 3D will take a hit in resolution and while I can’t find a smoking gun, the systems proposed infer a negative impact on 2D content; they will be sending more data and bandwidth is limited by the old DTV MPEG2 based system. Satellite and cable have an edge providing direct 3D programming since they are proprietary systems that can be changed to MPEG4 or other codecs (satellite already uses MPEG4).
Stereoscopic 3D is Just the Beginning
In the October 2009 issue of Widescreen Review is an article titled “Is 3D Ready For The Home?”, from Chris Chinnock providing in-depth coverage of all 3D technologies besides the stereoscopic one presented at CEDIA. On page 50 is a chart breaking down the individual application requirements for 4 types of 3D technology. The two applications mentioned here are in the Stereoscopic family with only one of the many possible applications being glasses-free. The other three technologies, Autostereoscopic, Volumetric and Light Field lead to numerous applications that don’t require any glasses at all. I think you will find the following paragraph of interest.
3D Basics You can Expect
Posted by Richard Fisher, January 14, 2010 8:36 AM
About Richard FisherRichard Fisher is the President of Mastertech Repair Corporation, serving north east Atlanta, Georgia, and has been servicing, calibrating and reviewing audio video products since 1981. Tech Services USA, a division of Mastertech, creates sites, communities and libraries for consumers and professionals to share their technology knowledge and learn from each other. These include The ISF Forum and HD Library. HDTV Magazine exclusively publishes HD Library and Forum for Tech Services USA.
Richard is ISF and HAA certified providing calibration and A/V reproduction engineering services. Richard is a technical consultant and also provides performance ISF and HAA home theater systems and calibration via Custom HT. Mastertech Repair Corporation is a factory authorized service center for Hitachi, Mitsubishi and Toshiba and a member of the National Electronics Servicing Dealers Association, NESDA, and the Georgia Electronics Servicing Dealers Association, GESDA.