In this connection one should keep in mind that the single camera, single projector simultaneous cross polarized technique used so successfully with 3D film for over 30 years may again appear for 3D video. LCOS and other modalities already have 4Kx2K resolution so a split lens with top/bottom images will give a 4Kx1K pair, sufficient for modest sized cinemas. SONY has recently started using a split lens for projecting LCOS 3D. It is well known that split lenses for cameras and projectors, either top/bottom or right/left, have been widely used for 3D for some 50 years. If one uses anamorphic lenses to film and project (e.g., as the standard CinemaScope format for theatrical 2D has done for decades), then one does not need to throw away any pixels or use complex image-degrading codecs. Anamorphic lenses have often been used for video and SONY even sold them for use with camcorders and consumer projectors a decade ago. I have described many of these formats for 3D in my previous articles and there are whole books and websites devoted to widescreen.

It is feasible to use a single imaging chip of 8Kx4K with high brightness lamp and high quality lenses to compete in terms of image quality and cost with the other projection approaches, and to create hires single chip or dual chip or frame sequential 3D lenses for video cameras that will avoid the horrific problems of matching all parameters of twin cameras.

NHK (the Japanese entity that uses government money to buy up the 3D rights to the Olympics and other world sporting events for their own amusement and never shows them to anyone) has been using 8Kx4K ((7680x4320 or 32M pixels with 4320 scan lines) UHD cameras and projectors since the Aichi Expo in 2005—the same Expo where NewSight Corp. installed an 180 inch autostereoscopic video wall—and it’s use for single camera, single projector 3D should be very straightforward. There is of course a substantial prior art on single camera techniques (e.g., see the SIT article on my page) and work continues (e.g., US 7215809, US 7181136, US 7170547).

All this points to the fact that the real reason for Real D’s current dominance in 3D digital projection is not possession of a special technology but the $100M or so invested. They would almost certainly have the same dominance if they had promoted any of the other 4 common 3D projection technologies instead. However the apparently proprietary and simple nature of the CP switcher was undoubtedly appealing. It appears that in addition to the approx. $75 to $150K cost of the hardware and screen (most for the 3 chip projector), Real D requires theaters to pay a $30K/year licensing fee and to buy the expensive (ca $3/pair-but see below) plastic CP glasses, the cost of which, in the fastidious and rich USA at least, is passed onto the customers. A family of 4 seeing 5 3D films a year will spend about an extra $60 for Real D glasses, $10 for paper glasses (i.e., theaters often add 50 cents to the ticket price) vs. nothing (presumably) for shutter glasses or recycled paper or plastic glasses. Incidentally, I have submitted this article to four Real D execs for comment, but they have decided that silence is the safest option. I agree.

The economics for theater owners may be impressive. There are about 6 circuits in the USA with over 1000 screens and I have heard of recent purchases of 500 3D projectors by an Indian company and 700 by GDC of Singapore. Assuming that a dual projector setup with equal brightness and image quality costs about half the $100K of a high end 3 chip, this would be about $50 million in savings for 1000 screens and if there is a $30K/year licensing fee that is another $30 million. On the other hand, $100 each for active glasses in a 300 seat theater equals $30K and supposing a very busy theater with 1000 shows/year with replaceable batteries and very durable 1000 use glasses ( or the ca. $100 Infitec glasses), this costs the theater $30/show or approx. 10 cents per customer. $50 glasses or ones that last twice as long lowers this to about 5 cents vs ca. 30 cents with the XPAND throw away glasses, but breakage and cleaning/battery costs will occur. A more realistic projection is 100 shows/year and this translates to $1/customer so the theater owners who do the math should be strongly motivated to use dual projectors with passive glasses or active glasses with replaceable batteries or perhaps the Infitec system if the cost of projectors and glasses is modest, the image is sufficiently bright, and the color asymmetry is tolerable for a two hour film. Of course it is very likely that soon they will have even better options with some version of the new stereoscopic projectors referenced here.

Passive LP or CP glasses can be made for about 30 cents each, or as little as 5 cents for LP in paper, and of course reused so that customers do not need to pay a premium. It is true that if one tips the head about 10 degrees to the side, the ghosting advantage of LP over CP disappears, but few find it necessary to watch 3D movies with head tilted and even with 2D virtually everyone keeps their head vertical. With shutter glasses there are no extra charges and no problems with head tipping but of course there will be some breakage and the theater must clean the glasses and replace dead batteries. Batteries in new glasses from 3DTV Corp should last for over 500 hours, based on the actual in-theater performance so far and 1000 hours if a smaller LCD is used. As with the XPAND glasses, a simple method permits assessment of remaining battery voltage to prevent their failure during shows.

3D WINDOW™ Universal Cinema System from 3DTV Corp : 3D WINDOW™ Universal Cinema System from 3DTV Corp with microprocessor controlled LCD shutter glasses that sync to any professional or cinema emitter from any companyThe current generation of wireless shutter glasses incorporates a microprocessor, which enables many desirable functions including power management, which extends battery life, and easy check on battery level. This renders the venerable CrystalEyes obsolete due to power consumption, bulkiness and weight, fragility and necessity of ca.10X higher emitter power due to use of 60 to 120 microsec sync pulses rather than approx. 18 microsec for modern glasses.

Image brightness is always a major consideration with 3D and the active CP technique (e.g., StereoPlate, Z-Screen) passes about 25-27% in the case of double LC layer (for pi-cells or surface mode LC with LC layer thickness about 5 mcm). Of course in multilayered (super high contrast—i.e., low ghosting) LC pi-structures the optical efficiency will drop further. The LCD shutter glasses (with a single LC layer as a rule) pass about 32-35% in case of pi-cells and about 20-25% in case of pi-cells doped with cholesteric LC. These will have an overall contrast about 100:1 (uncompensated) with a driving voltage no more than 12V in comparison with a contrast between 10 and 30:1 in uncompensated undoped pi-cells with driving voltage about 20V. Dual polarized DLP or LCD projection can pass up to a max of 38% (but probably typically below 30%) and up to ca 60% with dual LCD polarized internally (eg by Barco) or with use of special external filters (e.g., http://www.advisol.co.il/StereoBright%20home.html or http://www.silverfabric.de/html/sf_polarizers.htm ). Standard LCD projectors have significant chromatic aberration and existing polarization but the latter can be largely eliminated simply by a layer or two of common clear acrylic in front of the lens. There are many efforts to improve dual LCD polarized projection (e.g., WO 2005/121867, WO 2006/088275, WO 2007/070245).

Uncompensated CP and LP methods (i.e., normal theatrical paper or plastic 3D viewing glasses with just one layer of the plastic polarizer) used with CP or LP on projectors give a typical stereo separation ratio of up to 100:1 while the compensated (pi-cell or surface mode LC) active glasses currently used can give up to 500:1 on axis. ColorLink has reported up to 5000:1 contrast in compensated systems (e.g., see their glasses patent WO 2007/024713) which is better than the best Nitto Denko LP plastic sheets. Many others can quickly issue such products as the entire LCD display industry of necessity researches polarization tech, but until recently only a few have given serious attention to 3D issues (e.g., WO 2007/043153). In practice however, such complicated compensation is not used for active glasses. For example, the StereoGraphics CrystalEyes active shutter glasses use one rotated half-wave retarder to transform the elliptical polarization caused by residual birefringence of the liquid crystal into quasi LP for increased on-axis contrast (i.e., with the eyes looking straight ahead perpendicular to the LCD shutter), but with little increased contrast off axis, so the eyes see the periphery with poorer stereo contrast (i.e., more crosstalk) and the result averaged over the whole image should be about the same 100:1 contrast as with uncompensated passive glasses.

However, the bottom line is whether any of this makes a difference in the image quality and enjoyment by the average viewer, and it is my view that they will be equally satisfied with the cheapest method. For example, my own observations on a variety of monitors with the various types of wireless IR shutter glasses driven by our Universal Emitter show essentially identical image quality (ghosting, color, contrast) of the cheapest and most expensive models (i.e., $30 vs $800).