Rebel Without a Cause

My passion for stereoscopic displays guided me to the booths and displays I’ll describe. My method, which has not varied over the years, is to start at one corner of the hall and work my way to the other end of the hall, passing every booth. I think many people do this rather than select the booths that might be of greatest interest. Of course such selection would take planning and forethought but I prefer to make it an adventure. There are two problems with this method. The first is that somehow I miss interesting booths. Next is that I get interrupted on the way, because after three decades in the field, people know me. So I stop and talk to them, and sometimes they have something exciting to show me at another booth and we wander to it. In a trade show like this one with 550 booths, I can lose my way. The booths look alike and are in a repetitive pattern so it’s easy to get disoriented. Trade shows are an exercise in cognition and spatial relations as much as anything else.

I should say that there was little stereo at this show. You’d hardly know we are in a stereo boom in the cinema from the evidence presented here.

At the Pavonine booth (a Korean firm) I saw an autostereoscopic display with a raster barrier. The display had a limited head box and a visible raster. They also offer monitors with a micropolarizer technology from Arisawa, and what they showed look fairly good. The difficult with this display technology is that interdigitation of perspective views produces a visibility of image structure that tends to pull away from image quality. Moreover, displays like this that are line sequential have half resolution in the stereo mode, unlike field sequential displays that refresh the same pixel time and again. However, the 30 inch Pavonine had a fairly decent head box despite the fact that these displays suffer from a parallax instrumentation effect. Moving the head up and down will change the juxtaposition of the polarization elements and the underlying display so the image will become pseudostereoscopic. But they’re working on a way to overcome that using a wire grid polarizer that’s in intimate juxtaposition with the display elements themselves.

SeeReal Technologies had two desktop size displays, one with head tracking and one without. It’s an interdigitated stereogram using refractive optics or lenticules rather than a raster barrier. In one embodiment there is no head tracking and that display had an extremely small head box. I can’t believe it could be useful for anybody at a desktop who has to spend hours a day doing a job of work. Also, the image was ragged with jaggies. They showed another monitor using a sophisticated position finder that locks to your head location. Once again it has a small head box, but it can follow you, or your eyes and it will maintain a stereo image. I don’t know if the device slides the display’s image or moves the refractive screen. In the past this company has actually offered a display that did the latter.

For the head tracked display they’re using a field-sequential technology that on a liquid crystal monitor was refreshing at about 35 Hz a monitor. Unfortunately, it flickered greatly. Another problem intrinsic to this kind of a display is that only one user at a time can see a good stereo image.

I was told they also had a good holographic display but they kept it hidden from me.

At the Kopin booth they had a nice head-mounted stereoscopic display–with about VGA resolution. They also showed a 1280×720 display that could be viewed through a loupe, which was beautiful; and that could be the basis for an even better head-mounted display, for the fans of head-mounted displays.

When head mounted displays are combined with head tracking they give me and lot of folks a bit of a problem. I for one get dizzy. The explanation is that there is a breakdown of the visual and vestibular pathways. Once at a tradeshow years ago in San Jose I became a billiard ball in a pod simulator and got shot around a pool table a great speed. It was a trip but when I took off the display and got out of the booth I had to crawl to the StereoGraphics booth down the hall. Once there I hid on the floor out of site until I could walk. The following mourning when I woke up I suffered a vertiginous flashback.

PureDepth is one of a couple of companies that is using a technology I saw several years ago at StereoGraphics when the people who developed it in New Zealand brought it by. There has been some development. It’s a technology that uses two liquid crystal panels in superimposition. They have two versions, one having a greater front-to-back spacing than the other. The display has a certain charm. They also demonstrated an algorithm that can interpolate the front and back images in a way that can make it look like there’s a smooth transition between the two panels. Most of the material I saw existed on two planes, however. I was told that working on a licensing deal with a pachinko manufacturer. It sounds like a good fit. Also, at the Samsung booth they had a 40-inch panel that showed off the technology.

This is a volumetric display using layers. As far as I know, it was the Lumières–the French film and motion picture inventors–who came up with this first in the 1890’s. They used a series of transparencies shot with a view camera having limited depth of field. The transparencies were stacked on a light box. Curiously, I independently came up with approach this when I was 12 years old, by stacking Kodachrome transparencies on top of each other.

It’s an interesting technology and it may have a niche market applications. The most important niche market might be handheld devices, but handheld devices must use thin displays; and thin is not what PureDepth is about.

One of the problems that people in the stereoscopic display industry face has to do with the fact that liquid crystal panels just don’t refresh fast enough to be useful for the standard field sequential display using shuttering eyewear, like my invention, CrystalEyes. No matter what the manufacturer’s specification may say, because of the way they take the measurements, they just don’t indicate how suited LC panels are in this context. They work entirely differently from CRTs, and I haven’t found one off-the-shelf that will support the field-sequential technique. So it was nice to see a 19-inch field emission display from Field Emission Technologies that make the grade. But it won’t be available as a product for several years. Field emission displays can be refreshed quickly. In fact, they can be considered to be flat CRTs.

One thing that’s apparent, and has been apparent for years, is that rear-projection monitors are few and far between. I am interested in this technology because of the recent addition of stereoscopic capability to the TI DLP engine that is being offered for this application, and at this time many such monitors have appeared that will support the active eyewear field sequential approach — none of which were shown at this show. It’s curious that the first TV set available that can play terrific quality stereo images was not in evidence.

Despite the fact that there are excellent monitors from JVC using their D-ILA technology, and Sony using LCoS, and Samsung and others using DLP technology, I saw but two such monitors in 550 booths (I may have missed a few but they were few and far between). And they weren’t being promoted by the monitor manufacturers; they were just being used for display purposes. It’s sad to see the eclipse of such an excellent technology because s in terms of price-performance they’re outstanding. We live in a world in which flat, or actually thin and anorexic panels dominate.

Here is where I let you down as a reporter. I visited one booth that showed a cell phone proof-of-concept using two cameras to produce a stereo image on a lenticular or raster barrier display. I should know the name of the manufacturer and I should know if what I saw used refractive or barrier optics. Even though I can’t recall these important details (somebody send me the information if you have it–might have been Sharp) I think it was interesting. Although the lenses were something like half an inch apart they worked fine for close-ups of my face. Low values for lens interaxial are fine for close-ups and work especially well for wide angle lenses.

I was at SID for one day to walk the floor, but I did go to the awards luncheon that took place at noon on Wednesday the 23rd. I was pleased to see Actuality Systems get an award for their Perspecta volumetric display. They’ve gotten something very difficult to turn into a product; a problem that has eluded some pretty fine minds including people at Texas Instruments.

But most curious was the luncheon talk given by Charles M. Falco, who is a professor at the College of Optical Sciences at the University of Arizona. He delivered a lecture on the science of optics and the history of art in which he claims to have discovered that Renaissance painters used optical techniques to produce their perspective paintings. I think it has been clear for some time that Renaissance painters had used optical techniques like the camera obscura to help them in their painting. Moreover Renaissance painters did not discover perspective. What we call rectilinear perspective or optical perspective was well understood centuries before. You can see it in the paintings on the wall of the villas of Pompeii. You can even see it in the bas-reliefs of the Babylonians. Falco’s presentation was co-authored by David Hockney, the deservedly famous artist who chronicled my neighborhood in the Hollywood Hills for years with portraits and landscapes. I didn’t find anything controversial in Falco’s presentation but he alleged that what he was presenting was controversial. I may well be missing the point but Dr. Falco seemed to me to be a rebel without a cause.

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