« iepriekšējāTurpināt »
INTERNATIONAL SYMPOSIUM ON
TECHNOLOGY AND ARTS
Three-dimensional imaging from computers and film is reviewed. The
Sony, and Matsushita are described.
by David K. Kahaner
2. Japan Display 92 (12th International
Display Research Conference), 12-14 October, 1992, Hiroshima
(IIS is at the third part of the Tokyo
University campus structure of Hongo, Human three-dimensional or stereo Komaba, and Roppongi). Nearly 130 vision evolved millions of years ago as scientists participated, with 37 papers a critical survival mechanism. Euclid presented, 17 from outside of Japan. wrote about it in 280 AD., and research (The Proceedings are entirely in to duplicate our sense of depth vision English.) There is an active threewith artificially produced images has dimensional (3D) research community been going on since 1600 (in 1890 the in Japan. Last July (1991) the Institute first three-dimensional movies were of Television Engineers of Japan ran a shown at the Paris International Expo- small international workshop at which sition). Thousands of papers have been related research in Japan and the written. This report describes current European Community (EC) was surwork based upon the International veyed. Research activities related to Symposium on Three-Dimensional this are also described in my recent Image Technology and Arts, held from Scientific Information Bulletin article 5-7 February 1992 (in Tokyo), plus on virtual reality (“Virtual reality,” 16(4), industrial tours to NHK, Sony, and 43-45 (1991)]. Two upcoming meetings Matsushita.
also worth noting are the following:
Participation in the symposium was as follows:
DISCUSSION OF SYMPOSIUM 1. Second International Conference on
Artificial Reality and Tele-Existence, The symposium was directed by 1-3 July 1992, Tokyo
(For reasons that I didn't understand, (Visonics), L. Lipton (StereoGraphics), viewing axes of left and right eyes when the industrial participants from the P. McLaurin (University of South both are focusing on a point (converUnited States were small or very small Carolina), M. Holzbach (Asaca), and gence). Adjustment of the focal length companies. The Japanese were well J. Hamasaki (University of Tokyo). Of
J. Hamasaki (University of Tokyo). Of of the crystalline lens (accommodarepresented by Toshiba, Sony, NHK, course, any errors are entirely my own.
course, any errors are entirely my own. tion) is another clue, although this is Fujitsu, Hitachi, etc. Does this mean It is useful to make the distinction mostly monocular. Binocular parallax that large U.S. industry is not inter- between 3D, biplano-stereoscopic, and is the most important binocular clue, ested in three-dimensional imaging? multiplano-stereoscopic images. (This relating to the fact that each eye sees a Certainly not, as there are products dichotomy is due to L. Lipton.) True slightly shifted view of the image. Indifrom Bolt Bernack and Newman, Texas 3D images not only give the sensation viduals differ greatly in their ability to Instruments, Tektronix, and others on of depth but allow observers to "look use these clues either because of physthe market already. So where were they? around" to their sides and perhaps even ical impairments, training, or some Perhaps this symposium was not too their back. Biplano-stereo images are processing difficulties. This is much well advertised outside of Japan. Also, produced from (only) two original like color vision: people who lack it there was a meeting of the Society of images. They also can give a very real- entirely discover so at an early age; Photo-Optical Instrumentation Engi- istic sensation of depth but have no others whose abilities are below averneers (SPIE) at about the same time in “look around" capability. An observer age may go through their entire lives San Jose, CA. SPIE is a large meeting moving his/her head while viewing a accommodating in other ways. for which 3D imaging, especially holog- stereo image causes the image to shift Images can be viewed on electronic raphy, is one part, and it probably kept slightly, but no occluded visual infor- displays such as TVs, cathode ray tubes U.S. participation lower than normal.) mation comes into view and the per- (CRTs), flat panels, etc. or in hard
This symposium was supported by spective remains the same. Multiplano copy form such as a photograph, plot various electronics, television, and images are composed of more than two image, and so forth. Viewing images robotics societies in Japan, as well as original images and do have some look
original images and do have some look may or may not require the use of the Ministry of Posts and Telecommu- around capability. An imaging system special glasses. Anaglyph images require nications (MPT). At the opening cere- in which the image aspect changes
in which the image aspect changes red/green glasses and most people are mony, MPT representative Saito depending on the observer's viewpoint
depending on the observer's viewpoint familiar with these from a large number explained that 3D is considered the is called autostereoscopic. In describ- of motion pictures (in the 1950s and most important research project that ing systems, the distinction between 1960s) that required them, but their his ministry is currently undertaking. A 3D and stereo images is often ignored. use can be traced back to as early as funded 5-year project will focus on Indeed, there are "3D" and even "4D” 1858. Anaglyph techniques can be used developing 3D image transmission workstations on sale, but this almost
workstations on sale, but this almost for viewing either still images on paper technology to permit transmission of always means three-dimensional images or dynamic images such as films. these images over optical fiber. Appli- projected onto a two-dimensional (2D) However, the current trend for films, cations are seen to be TV telephones display device. I will try to use the terms video tape, or computer screen images and conference systems. MPT has allo- accurately but won't change terms that has been toward polarized glasses cated $1.3M in FY92 and plans to allo- authors use in describing their work. instead, or systems without glasses. cate at least that much in subsequent In viewing the real world, it is known Current work seems to be primarily years. Some cooperation with overseas that the sense of depth is the result of directed toward stereo vision, although research groups is being considered. ten or more different factors. For exam- the main technique for full 3D imaging (See also the electronically distributed ple, overlapping or occlusion, where is holography, i.e., the reconstruction report on MITI's plans for an “Image" one object obscures part of another, is of the object wavefront. The original laboratory, image.lab, 20 Feb 1992.) a depth clue that does not depend on principle involves illuminating the object
I would like to express my thanks to having two eyes. Another monocular with a laser and simultaneously recordseveral attendees who patiently clue is the image of road edges that we ing the reflected (or diffused) light from explained many aspects of this technol- expect to be parallel. Similar monocu- the object and a reference beam from ogy to me, especially M. Pusch (Heinrich- lar clues are related to retinal image the laser, creating an interference fringe Hertz Institute, Germany, and Uni- size, areal perspective, shading, shadows, pattern. The recorded pattern can later versity of Tokyo), W. Fetter texture, etc. An important binocular be illuminated with the same laser to (SIROCO), R. Kroiter and P. Panabaker clue to distance from the observer is
clue to distance from the observer is reproduce the image. Work in holo(Imax), M. Starks (3D TV), H. Tilton the difference in angle between the graphic techniques has recently focused on using conventional light rather than Nevertheless, we are still years away images are often too dark or the color a laser and the creation of holographic from practical holography in our homes is poor. The process is simple in principle stereograms, in which multiple images such as holographic TV. For example, but tricky in practice. For example, of an object are recorded by ordinary any practical holographic display device when viewing computer screens, the cameras at different positions and a relying on Benton's approach will color filters need to be matched to the hologram of each image is recorded require time-bandwidth products far screen phosphors. Otherwise there is sequentially. Holograms can provide a exceeding those available with single cross-talk and the observer becomes very high resolution and geometrically channel acousto-optic modulators and confused by
by the stereoscopic accurate image that can be viewed will require other techniques such as information. without glasses and in principle is multichannel modulators, parallelism, If right then left eye images are disindistinguishable from the original etc.
played sequentially from a source, and object. But initial enthusiasm for There are some other 3D techniques. a synchronized shutter system in front holography has waned somewhat as An interesting one (S. Yamada, Shibaura of the eyes allows the right eye image to practical problems reproducing color Institute of Technology) involves pro- only enter the right eye, etc., then stereo and providing dynamic displays have jecting a sequence of cross-sectional vision can be observed. The shutter can not yet been effectively solved. Also, “slices” on a screen whose diameter is be mounted in glasses that are matched many techniques for holographic changing. If the moving speed of the with a display in which two constituent imaging produce images smaller than screen and the scanning speed of the pictures are presented in alternation observers would like to see. As one images are fast enough and synchronized instead of simultaneously. The glasses researcher commented, holograms properly, 3D images can be recognized occlude one eye and then the other in provide too much information, i.e., it by an afterimage effect of human eyes. synchronism with the image presentaisn't really necessary to completely Yamada's main application is to view- tion. This is often called “field sequenreconstruct the wavefront to have an ing of medical images.
tial." This method avoids the retinal effective image. However, some of the The “Pulfrich” effect is another that rivalry caused by anaglyph viewing but most exciting developments in this area can be used for stereo vision on a nor- can introduce other discomfort such as are being carried out at the mal television with glasses. This uses the increase of flicker (on 60-Hz disMassachusetts Institute of Technology the brightness dependent delay-time plays), the introduction of time paral(MIT) media laboratory under the direc- of the human eye-brain to create the lax between the two images, or the tion of Prof. Stephen Benton. Benton's impression of a pseudo-stereo picture. possibility of "ghosting” between the early claim to fame was the invention This was demonstrated in Germany a images due to phosphor persistence. of the white light transmission (dubbed year ago to broadcast pseudo-stereo On computer displays flicker can be rainbow) hologram and, more recently, via normal television equipment. solved by increasing from 60 to 120 the practical demonstration of holo- Observers saw (with the help of a dark frame refreshes per second, although graphic video. The laboratory is also glass filter on the right eye-glass lens) this is accomplished by halving the working on holograms that are in full stereo pictures when the objects moved number of pixels that are painted per color, large size, animated, and can be from the right to the left on the screen. frame, perhaps leading to lower resototally synthesized by computer. Per- According to different velocities of lution. (Also see the comment by Starks haps most importantly, this work has objects in different depth levels, a stereo- below concerning “apparent” resolure-energized the field and forced picture was seen. One advantage of tion of 3D images.) Most glasses-based researchers to take a more serious look this technique is that the observer can shutter systems use LCDs, which work at ongoing related work. At this sym- choose between watching with glasses with polarized light. Currently, glasses posium papers discussed applications (stereo) or without (2D). The major using LCDs can provide good switchof holography to medicine, cameras for disadvantage is that everything must being speed and reasonable extinction of holographic imaging of moving objects, in motion. (There were no papers the alternating lenses. The electroand holographic TV using liquid crys- presented at this symposium on the optical polarizing shutters now in use tal displays (LCDs). All the speakers Pulfrich effect.)
transmit about 30% of the unpolarized pointed to Benton's work as years ahead, A serious issue with either 3D or input light (rather than 50% for peralthough he did not attend the sympo- stereo vision is viewer comfort. This fect polarizers), and this reduces the sium. (The work is known from his can range from little-or-none to phys- image brightness a little, but in pracpublications as well as his recent visit iological disturbances that can cause tice this does not appear to be a major to Japan.)
nausea in some observers. Anaglyph problem. Some eye-glass shutters are connected by wires to the monitor 100:1. The main problems are that they since their inception in cave dwellings (tethered); others are controlled by are expensive to produce, especially in and will continue to adapt. (Kroiter's] infrared and are wireless. Another system large sizes, and difficult to manufac- work is limited mostly to entertainuses a polarizing shutter mounted on ture because of low production yields. ment and not the distribution or prethe display device and eye-glasses with For future displays Uchida felt that a sentation of information. When one fixed (circularly) polarized lenses. While target specification that would be leaves the realm of entertainment and this reduces the complexity of the eye- achieved in a few years was as follows: enters scientific applications, one finds glass system, the large screen-covering
that it is information that is most imporshutter is expensive to produce and is Resolution: 50 um in pixel pitch
tant, not the general public's accepfragile. Lipton (StereoGraphics) Diagonal size: 10-40 in, with 100 in desirable tance of an image for entertainment.") commented that his company produced Viewing angle: +45° vertical,
Nevertheless, in the past few years such systems for Tektronix but had
many objective studies of binocular many difficulties and is now using shutter Response time: 15 ms
vision and perception have been perglasses. For images that are generated Reflectivity or
formed and there is now a substantial by film (as opposed to those generated transmittance: 60-80%
collection of data that are being used in by computer), it is extremely important Contrast ratio: 50:1
the planning of real systems. For that all aspects of the production process, Grayscale: 50-100
example, work to determine the angular including film registration, color balance
field over which 3D vision was effective during the developing, balanced He also noted that among the most has led to the design of large screen illumination during projection, etc., be promising ideas was the use of opti- theaters by the Canadian company Imax. maintained.
cally addressed, amorphous silicon plus Also, the Russian author S. Amelianova Flat panel displays are frequently ferroelectric liquid crystal, with 5-10 um wrote a paper on a very careful used as part of a stereo imaging system. resolution, 70 us response time, and
resolution, 70 us response time, and experiment to develop methods to Among these, liquid crystal displays 60:1 contrast ratio. The main problem evaluate observer's 3D vision thresholds are popular. The “standard” type LCD here seems to be that the active area is in 3D perception and parallax. is a direct matrix display, which has a only about 1.4 cm, currently.
Amelianova's thesis was a 1991 Oscar structure of light modulating material As mentioned above, 3D vision is winner for technical achievements. sandwiched by horizontal and vertical partly physical, and partly psychologi- (Starks notes that Russian/Soviet work stripe electrodes. The horizontal elec- cal, and hence it is difficult to accu- in 3D is substantial.) Other studies are trodes are scanned one by one and sig- rately quantify and resolve problems even more focused on perception. For nal voltages are applied to all the verti- associated with it. For example, M. Starks example, a strange but common visual cal electrodes according to the image points out that “ordinary consumer sensation, named “Ganzfeld,” concerns on the selected horizontal electrode. NTSCTVs with well done VHS stereo- what happens when our total field of Plasma display panels and electro- scopic tapes look equal or superior to view is obscured by a single light color, luminescent displays have fast response any HDTV I've seen ... due to the fact such as in a fogor a white-out. This has but LCDs do not, although they have that stereo will usually have a greater been a basic topic for psychologists high resolution and good color repro- information content than mono and since the 1930s, and an experiment was ducibility. Increasing the number of the highly sophisticated image process
the highly sophisticated image process- reported at the symposium by M. Hara scan lines rapidly decreases the average ing systems in the brain have been (Asahi University). The problem is far brightness of LCDs. But great strides evolved to take advantage of this." from settled, and much more research have been made in this technology, and Another psychological issue is related is needed to understand how we process at least one symposium participant, to perception of images. We are accus- binocular images. T. Uchida (Tohoku University), felt that tomed to seeing close-up pictures of I was surprised to discover the qualthey will be mass produced and suit- people framed by the edge of our view- ity of work going on at the Industrial able for portable PCs and workstations ing screen, photograph, etc. R. Kroiter Products Research Institute of the in the near future.
(Imax) wondered if we will be as ready Ministry of International Trade and An active matrix display has a diode to accept heads cut off at the neck Industry (MITI), located in the city of or thin film transistor (TFT) at each floating in space? (This may be a real Tsukuba and presented by T. Takeda. pixel. These displays can provide fast concern, but not to everyone. McLaurin This project is designed to measure response time (less than 10 ms), good commented to me that “we have all basic ocular functions, eye movement, display quality, and contrast better than adjusted to new presentation formats accommodation, and pupil diameter
during actual vision of 3D displays. helmet-mounted displays, suffer severe project onto a screen 29 meters wide The fundamental motivation here is to limitations due to the poor resolution that is specially metallically coated after determine if there are any hazards to of their LCD displays. However, imaging erection. This kind of technology is users, such as the concerns once voiced applications are also rife in science. In still far too expensive to be available in that the electromagnetic radiation from 1982, C. Smith wrote that “future gen- the home, but it is gratifying to see such video display terminals (VDTs) would erations will be astonished that for a hi-tech ideas made into successful be harmful. The group has developed a few decades in the 20th century we
products. 3D optometer that is capable of mea- were happy to accept these small flat L. Lipton (StereoGraphics) suring these quantities yet allowing the images as a representation of the real
images as a representation of the real described the infrastructure necessary eye to move freely with a 40° horizontal three-dimensional world." It seems for practical use of electronic stereo and 30° vertical range. One important obvious that in robotics, photogram- displays by working scientists. result of their experiments is that the metry, pattern recognition, etc., three- Stereo Graphics markets one of the most greater the depth stimulation presented dimensional imaging would be a great successful of these. Symposium particby the stereo pictures, the more the help.
ipants from the West were well aware observer's focus point shifts. Observers P. Panabaker from Imax made an of this and spoke highly of it, but Japanese then perceive blurred images and interesting presentation about commer- attendees were strangely unaware of it. struggle to reduce the blur and adjust cial applications of 3D in theaters. Imax Lipton made another point that in some to the depth perception. The adjustment is a Canadian company established about fields of science, stereo imaging is part process produces more visual fatigue 15 years ago with the assistance of the of the training and hence professionals than when viewing 2D images. Creators National Film Board (NFB) of Canada. in these disciplines use it as a standard of stereo images strive to evoke as much (Those readers who, like me, are film tool, cartography being an obvious depth sensation as possible to heighten buffs will know that NFB has been at example. However, in other areas, stutheir viewer appeal and may unwit- the forefront of film making since the dents and young researchers are not tingly add to viewer fatigue.
earliest days of cinema.) Imax builds similarly exposed and these people have There is no doubt that entertain- complete theaters and shows films that to be alerted to the possibilities. I ment has been a prime mover in this it produces itself. Almost 2 years ago, I admit to being persuaded by this and subject. Imax, mentioned above, builds wrote about Fujitsu's 3D computer feel that there are two points here. large stereo motion picture systems that generated movie at the Osaka Expo'90 First, that research in the general area are used in theaters around the world. (see the electronic report fujitsu.3d, of stereo or 3D imaging will go forNHK, the Japanese governmental TV 25 April 1990). This exhibit was created ward. Second, that it has already prosystem, is hoping to develop stereo TV, by Imax, which also did the Suntory gressed to the stage where it is now and presumably its main customers will exhibit (which I did not see.) Panabaker practical; computers that can generate be ordinary viewers, not scientists. NHK described the care that is required to one view perspective can just as easily scientists are already talking about produce 3D films that are not only very generate a slightly different one. Modbroadcasting of stereo images in the realistic but also comfortable to watch erately priced systems exist that can 21st century. All these applications for long periods of time. For computer convert this to stereo images on most involve enhancing the sense of “pres- graphics, Imax generates and records workstations and even many PC monence" or "reality" and are often accom- images at 4000x3000 pixel resolution, itors, and these can be viewed comfortpanied by enhancements in audio pres- recorded on separate left and right ably by any one of several polarized ence as well. Similarly, high definition 70-mm film frames, and has shown such glass systems, wired or wireless. I believe TV (HDTV) is another related tech- films as early as the mid-1980s. For the that scientists now using computer nology, and it is obvious that stereo TV Fujitsu exhibit Imax used lesser resolu- graphics could put these techniques to is being viewed as the next step beyond tion (2048x1500) but produced excellent use immediately. Also useful, HDTV. NHK estimates that in 1990 11 minutes of full color, fully shaded but for a different constituency, there there were about 80,000 viewers of rasterized images, with separate film are not only stereo slide and print HDTV in Japan but that the number strips for each eye. Each frame required cameras available but a $3,500 Toshiba would be 10 million by the year 2000. It several minutes of computation on camcorder as well. (M. Starks pointed is also not surprising that research in VP200 class machines and the project out that the Korean Goldstar Com"virtual reality” (VR) is associated with spanned 21 months. The two Imax pany has recently received a patent for stereo imaging. At the moment, how- projectors are huge--each requires more a 3D VCR.) All of the above are barely ever, VR systems, especially those using than 15 kW of arc illumination--and more expensive to purchase and process