The world is 3D. But everything that’s a reproduction of it-newspapers, TVs, computer displays-we watch in 2D. It’s surprising the way we’ve gotten used to viewing and working with all this 2D. Have you ever, while playing a video game, craned your neck to the left to try and see what was behind something on the screen? Did you feel foolish about it later?
Think about 3D TV for a while: your favourite TV serial recorded and broadcast in true 3D. Imagine your family sitting all around the TV box, instead of in front of it, or perhaps even walking round it to get different perspectives. Sounds far fetched? Science fiction, right? Well, not exactly!
Yes, there’s still quite a while to go before we’ll be able to buy something like that off the shelf. Some say it’ll be as soon as the year 2020, ‘the year of perfect vision’, that we’ll get true real-time 3D displays you can walk all around. Others aver it’ll be at least a fifty years from now. The truth is, no one knows for sure!
Our aim here is to inform you of some pretty amazing prototypes out there-devices that are the state of the art in holographic and stereoscopic techniques. And all developed and showcased today-not 50 years hence!
The Technologies
There are many 3D display technologies being worked upon. Three prominent categories are stereoscopic, holographic-in-air, and enclosed volumetric displays. Stereoscopic displays may require special glasses, IMAX-style, or may not, but they’re basically just two different shots of a scene, each fed to one eye, to create the illusion of 3D.
The term ‘holography’ means a lot of different things, but it’s been popularised in movies such as Star Wars, with R2-D2 projecting the image of Princess Leia-so think about holography as ‘the Star Wars’ thing’!
Enclosed volumetric displays are probably the least known of the three-these are 3D renditions of scenes within a spinning volume. We take a look at examples of each of these.
Stereoscopic Displays
These are more advanced than you might imagine. Take a look at NuVision’s Web site (www.nuvision3d.com): “Welcome. To the most advanced stereoscopic technology available. To absolute, true depth, flicker-free 3D realism. To a world as real as the one you live in. Welcome to the future.” 
Monitor overlays, in conjunction with special glasses, can afford a degree of 3D realism
One of their products-the SX line of display kits-uses a “high-speed liquid crystal modulator” that you use as an overlay for your existing monitor, in conjunction with special glasses, to give you 3D realism. Now if only this system were cheap enough for the majority to afford!
There are several such systems in existence, and each claims to be better than the other. We’ve all experienced such 3D in IMAX theatres; there’s nothing new about such products. Personal 3D has, however, seen improved realism in the past decade. But who wants to wear comical-looking glasses?
Mark Lucente of IBM’s Thomas J Watson Research Center wrote in 1997, “Real-time 3D holographic displays are expensive, new, and rare. Although they alone, among 3D display technologies, provide extremely realistic imagery, their cost must be justified. Each specific computer graphics application dictates whether holovideo is a necessity or an extravagant expense.”
And expensive and rare they continue to be. An example of a holovideo system is the Heliodisplay of IO2Technology, which projects TV, streaming video and computer images into the air-the images actually float in mid-air! The Heliodisplay is compatible with most video sources, and, in fact, is interactive: it’s a floating touch-screen. Remember the movie Minority Report?
A post on a popular geeks’ forum said, “News of a 3D display that projects an interactive image into thin air, the Heliodisplay, is not exactly fresh. What is new however, is that this once far-fetched conceptual object is now real, working and being sold. The Heliodisplay projects into the air-without the need for a special screen-images fed to it from a variety of sources. In a way, it’s a working version of R2D2’s holographic projection system.” 
IO2Technology says the Heliodisplay is the world’s first interactive video-into-air display. At bottom right is a close-up of the observer’s hand ‘going into’ the image
So how does it work? Well, the display is a box no bigger than your PC cabinet lying on its side. This box sucks in air, ‘conditions’ it, and then expels the air and uses lasers to project images on to this ‘conditioned’ air. Sounds vague? It is, and IO2 isn’t going to give you any more details about the working of the system just yet. They do, however, inform you that the air is “safe” and say that even if you run the machine for a full day in a sealed room, the air would still be breathable!
Our best guess is that there’s ionisation involved, but in the end, we’re as clueless as the rest of the world! The fact is that here we have a truly holographic display that works!
So have we attained true 3D Nirvana then? Well, not quite! The problem with IO2’s display is that it is still nothing but a computer display. Even with this display, craning your neck to see what’s behind that box in a game will not help you see any better. Moving to the side will give you reduced visibility, just like with a computer monitor!
The great thing is that this is a step forward, and it’s still a display technology that projects an “emulated 3D image” (as with the 3D in games) into thin air, and allows you to interact with it. You can actually ‘touch’ your Start button, and pass your hand through the scenery. It’s also remarkable that you can connect almost anything with a video-out function to this device!
The Illusion Of Holographic Displays
Laser Magic Productions says on their Web site, “There is no easy way of creating a walking, talking ‘holographic projection’ in the real world. Real laser-created holograms just don’t work that way. There is no current technology to project a real life-sized, moving, talking hologram in a public place that permits a person to walk all the way around and view it from all sides. 
We think the two initial markets (for holo-TV) will be in medical visualisation and military applications”
Dr Harold “Skip” Garner, Jr Professor of Biochemistry and Internal Medicine, University of Texas Southwestern Medical Center at Dallas
The virtual 3D world where you can project anything you want into thin air like The HoloDeck of Star Trek fame is still a long way off. Laser Magic Productions of Playa del Rey, California, has developed a family of 3D projection technologies that accomplish the illusion of Holographic 3D Projection.”
“Illusion”? Yes, there are five technologies that Laser Magic Productions mentions, all of which produce the “illusion” of 3D projection. These include the HoloTank, a 3D volumetric display created by projecting scanned laser light or vector video graphics into a liquid medium resulting in 3D holographic-type projections. Moving laser or video images are projected into a liquid chamber (like an aquarium) in which proprietary microscopic particles are suspended. When vector graphics such as words, line art, cartoons and abstract geometric images are projected into the Tank, they are imaged in 3D, resulting in holograms within the Tank.
Another innovation by Laser Magic Productions is the LaserCube, a way of displaying laser imagery in 3D space without particulates in the air. Images projected into the LaserCube appear to float in space. To give you a flavour for the kind of technology that goes into laser imagery, a LaserCube consists of two elements: the Imaging Cube and the Projector. The Projector is what projects the images, and the images are formed within the Cube.
This Imaging Cube is made up of multiple parallel imaging screens created from a fibre-optic-like material. This material acts as the holographic medium-remember that for a hologram to be formed, a medium is always required! 
The HoloTank can project video images into a liquid medium to produce 3D video images with real depth
Now, when laser light is projected into the Cube, the light forms an image on the first of the imaging screens, and then passes through to the next-and so on. The same image appears on each of several parallel planes, creating the holographic illusion of depth and perspective.
What about the Projector? That’s where the images come from. How does it work? There are several modes of operation, and in one mode, three lasers are mounted within the Projector. These produce red, yellow and green laser beams. The three beams are directed through a scanning system that creates abstract laser images. These have an interesting property: they move and change in response to sound-be it music, voice or even ambient audio.
Now, one can play something so that it acts as the sound source, or, ambients sounds (if any) can be used as the audio source. The circuits in the Projector are thus able to translate this audio into laser images that are projected out of the Projector and into the Imaging Cube. Thus, by modulating audio instead of the laser light itself, one can control the image that is formed.
Because of the arrangement of the optical imaging material within the Cube, the projected laser images appear like dancing holograms. One can walk around and view the results from any angle. 
Images projected into the LaserCube appear to float in space
A second method of displaying holograms entails using high-power lasers and a larger Imaging Cube suspended overhead. In this arrangement, the Projector unit containing the lasers and control systems is remotely mounted, and projects from a distance into the Cube. The projected images materialise with no apparent origin because laser beams are not visible in the air until they hit the Cube’s imaging material. So there’s no way to tell where the images are coming from!
There are several uses for holography besides just entertainment: advertising and medical applications are just two of them. But why is true 3D so difficult? The answer is basically the computational power required. As an example, Apple proudly mentions Voxel Inc.’s Digital Holography System (DHS), which uses Apple computers: “A patient with a brain tumour lies motionless on the operating table. The surgeon must effectively remove the tumour without damaging surrounding tissue. Previously, this was undertaken without the ability to capture in 3D the anatomical relationships within the patient’s body. But now, Voxel’s Mac-based DHS gives surgeons a life-size, 3D X-ray view of the patient.
“Ordinary X-rays only provide 2D representations, and technologies such as MRI and CT provide only ‘slices’, each representing a 2D picture of a single plane within the body-the surgeon and radiologist are left to imagine a meaningful whole. Surgeons have long needed a 3D X-ray view of the patient, giving them a clear picture, for example, of how deeply to cut to completely remove a tumour. By providing a life-size, transparent ‘twin’ of the patient, Voxel’s technology does just that.
“If ever there was an application that requires extreme processing power, it’s volume imaging,” says Voxel founder and CIO Michael Dalton.
So how are 2D ‘slices’ turned into holograms? Surgical candidates first undergo a CT or MR scan, resulting in a series of 2D image cross-sections that are converted to DICOM (Digital Image Communications in Medicine) format. The DICOM images are transferred to a computer. A piece of software called the Voxpad then reconstructs the 2D slices into a 3D view of the anatomy, which simulates the corresponding ‘Voxgram’.
In doing so, the computer must process from 20 to 120 megabytes of pixel data as many times per second as possible to achieve the real-time 3D manipulation required to approximate the Voxgram. “The raw processing power of this application really stresses computer systems,” says Dalton.
Voxel’s DHS uses 2D slices. That’s the key here. It’s no simple matter to display holographic objects in motion-to just use multiple cameras to record a scene, then play it back in 3D. But steps have been taken along that direction too.
2020: Holo-TV?
This year, as recently as June, the first ‘true’ 3D movies were created, by Dr Harold “Skip” Garner, professor of biochemistry and internal medicine at UT Southwestern, at the UT Southwestern Medical Center. It’s been reported: “In a small research laboratory at UT Southwestern Medical Center, a grainy, red movie of circling fighter jets emerges from a table-top black box, while nearby, a video of a rotating human heart hangs suspended in a tank of gooey gel.”
The report in Science Daily goes on to say that such movies will not be commercially viable for entertainment purposes anytime soon, but Dr Garner and his holo-TV have been featured in Popular Science’s June 2005 issue. The magazine put Dr Garner’s achievement in a list of the top five “great ideas for the future.” 
The Perspecta Spatial 3D System’s 20-inch dome, displaying a 3D image of a heart. It occupies a volume in space, giving users an all-encompassing view
Image courtesy of Actuality Systems Inc., Bedfort, MA, USA © 2004 David Shoppen
“An important next step is to take our proof of principle technology that we have now, and move it into a commercial entity,” said Dr Garner. “We think the two initial markets will be in medical visualisation and military applications, such as heads-up displays for helmets and military aircraft and coordinating battlefield information.”
“I predict that by the year 2020, that being the year of ‘perfect vision,’ we will have holo-TV in our homes,” said Dr. Michael Huebschman, a researcher in Dr Garner’s lab and one of the developers of the technology.
Dr Garner’s system is based on a small chip covered with about a million tiny mirrors. According to Popular Science, the basic principle is this: a digital micromirror device (DMD) is used, which is made up of nearly a million reflective panels. Each of these reflective panels can be angled by a computer several thousand times a second (!) to reflect or deflect beams of light, thus producing moving pictures. The DMD can be programmed to produce a desired image.
Dr Garner’s key insight was that he could use laser light on the DMD instead of using a regular projection bulb. He programmed the DMD to reflect a sequence of 2D interference patterns-called interferograms-that alter the laser in such a way that it produces a 3D hologram. (The summation of two or more interacting electromagnetic waves-light, for example-is commonly known as interference between the waves). So what’s happening here is basically a sequence of 2D interferograms becoming responsible for a 3D image.
This, however, was not Garner’s biggest challenge: remember that for any 3D image to materialise, a volume that acts as a screen is required. That was the challenge-to find a suitable projection surface that has a volume.
A column of mist should be OK, because it has particulates on which light can be reflected. But mist diffuses the projected image. Garner is therefore working with a display composed of layers of micro-thin LCD panels, each of which can (when electrically charged) be made clear or opaque. The panels flash on and off in quick such quick succession while assemble the hologram that the speed convinces the eye it’s seeing a solid object.
Other such displays exist today, but instead of using a series of 2D interferograms, they slice up a 3D image and send the 2D data sliver by sliver to the LCD screens. This method requires far greater processing power. Which is why Garner’s approach is the most viable solution for 3D TV. “We’re sending the 3D images as a 2D interferogram,” Garner says, and this doesn’t require any more bandwidth than today’s TV signals-“so we can use the current broadcast infrastructure.”
As for creating the holographic content, it would have to be recorded with a series of cameras shooting from different viewpoints.
Dr Garner and his research team-Dr Huebschman and programmer Bala Munjuluri-have published details of their system in several publications. For technical details and sample holographic movies, see http://innovation.swmed.
edu/research/instrumentation/res_inst_dev3d.html. What we’ve provided here is a rough overview, and to understand the system in detail, a good knowledge of interferograms is essential.
Think of Garner’s assembly as Dr Bell talking on his ‘telephone’ with his assistant Watson, compared with our casual usage of cell phones today. 2D interferograms bounced off the million mirrors of a DMD may well be the prototype that leads to 3D TV-who knows?
Perspecta Spatial 3D (www.actuality-systems. com) urges, “End Flat-Screen Thinking.”
Think of it as a plug-and-play crystal ball. The Perspecta Spatial 3D System includes a 20-inch dome displaying full-colour and motion images that occupy a volume in space, giving users a 360 degree all-encompassing view-and without the need for goggles.
Perspecta renders all movement from widely-used open-standard 3D applications. The resolution of the gizmo is a 100 million voxels! A voxel is a volumetric pixel.
The Web site proclaims, “Gone are the days when colleagues squeezed in behind your desk to view an HIV molecule or patient MRI. With Perspecta Spatial 3D, everyone sees everything all the time.” The system exploits the fact that the brain can integrate a series of 2D cross-section images (the device spins at 730 rpm) into a volume-filling 3D image.
From a whitepaper on the site, we learnt that spatial 3D is different from flat-screen 3D projection or the use of stereoscopic goggles. Spatial 3D refers to 3D imagery that truly occupies a volume of space. The scientific term for a spatial display is a ‘volumetric display’.
The Perspecta Spatial 3D System projects 3D imagery that seems to hover inside a transparent dome. “Spatial 3D gives you a unique perspective on information because you can walk around the imagery to inspect it from different angles.” And the site emphasises that the 3D imagery is “truly three-dimensional; it isn’t an illusion and doesn’t require wearing any goggles.”
The Perspecta system is probably the closest we’ve gotten so far to the holy grail of true 3D projection. So what’s missing? Not too much, except that the ‘crystal ball’ isn’t too large, and that you can’t interact with it in any way. And, of course, it’s expensive-$40,000 (more than Rs 17 lakh). But still, the system does blur the line between sci-fi and actuality-pun intended!
The Way Ahead
The list of systems we’ve mentioned above is in no way exhaustive. There are virtually tons of different 3D visualisation systems you’ll find if you Google the appropriate terms. We haven’t bothered with mentioning more of them here because there are just too many! 
The Perspecta Spatial 3D System displaying a breast tumour. Medical researchers and surgeons benefit tremendously from 3D views
Image courtesy of Actuality Systems Inc., Bedfort, MA, USA © 2004 David Shoppen
One thing we can expect is for such systems to become more common. For example, in July 2002, electronics giant Sharp, together with Japanese telecoms operator NTT DoCoMo, launched a mobile phone with a tiny 3D LCD screen, and more than 2 million units have been sold. And in November of 2003, Sharp released a notebook computer with a 15-inch LCD screen that can switch between 2D and 3D viewing modes.
“All” we want right now is for such systems to be scalable in terms of size, and for them to become cheaper. For technological reasons, it will be several years before something like the Perspecta Spatial 3D System can be hooked up to a PlayStation or Xbox. Also, the display technology needs to improve-at present, full-resolution images are displayed in only eight colours, and brightness and contrast could be improved. And, of course, there’s the issue of raw computational power-but of which, of course, we can be assured that we’ll get up to speed in a few years.
With goggles and a degradation of overall experience, it may not be that far off: Actuality Systems says it might build lightweight versions of the 3D display that could be marketed to consumers for use with video game consoles. CTO Gregg Favalora says the company has plans to begin work on such a display. Favalora also says, “Component costs will decrease. There could be a desktop unit in the future.”
And here’s the interesting part for all you gamers reading this: Actuality Systems has produced an SDK for Perspecta that is an extension of Mesa-the open-source implementation of OpenGL-which could open up gaming possibilities. In which case, true-3D DOOM 3 could well be something you’ll play in your lifetime!