When it comes to 3D video displays, it is actually all in your mind. What this means is that all vision, even what you see in the physical world around you, is a set of incomplete sub-images that are transmitted to your brain through the receptacles of your separate eyes. Inside the great computer within your head, these sub-images are used to create a composite three-dimensional rendering based on the data received.
As a result, most forms of 3D display technology are basically ways of tricking the eyes into seeing just enough of a set of sub-images so that the brain will do its duty and provide 3D interpretation rather than settle for thinking of it as the flat two-dimensional view that it actually is. While the data received in the physical world is practically infinite in nature, that which is provided by any form of 3D image production is limited by the technology that produces it. The image cannot be infinite in scope but it must contain enough data for the brain to construct useful interpretations of what it receives. It has to be fooled into thinking it is seeing a real 3D image, in other words.
3D images have been around for a very long time and were made possible on a practical basis by the invention of optics. The stereoscopic picture viewers of the 19th century and the strange 3D glasses used in 1950s movie theaters are steps along the road toward ever more realistic displays.
For a long time, 3D display technology was built around the provision of these types of external modifiers. The viewer needed some form of a dual-lens apparatus so that one eye could see one view of the subject and the other eye could see a slightly different view of the same object. While this works fine, it is, in essence, a retail form of 3D viewing. Each individual needs their own set of viewers, or one set of viewers must be shared back and forth between many individuals.
The search for a practical 3D technology that could be shared among large numbers of people in real time has taken quite a while to accomplish. These wholesale viewing methods have finally achieved a high level of quality coupled with an ever-falling price for the equipment needed on a consumer level. Yet the move from a stereoscopic, glasses-based, display to an autostereoscopic, glasses-free, solution was not an easy one.
In today’s world of 3D displays, there are several different approaches which each have virtues and drawbacks to consider. Those of the glasses-based stereoscopic displays have already been mentioned. In terms of 3D video monitors, there are several major avenues in production or under development at this time.
The first is what is known as an occlusive, or parallax barrier, screen. This produces a 3D image by transmitting two interleaved views that are similar to the slightly different views revealed by your own eyes. An opaque barrier pierced with carefully placed viewing slots allows one eye to directly see one view while the other eye sees through the viewing slot only at an angle and picks up the second view to the side. The big drawback of a strictly occlusive view screen is that it is suited only for small screen displays such as might be found on a smartphone. The 3D effect it offers is mostly viewable only from straight ahead or very nearly so. It is also somewhat dim due to the blockage imposed by the parallax barrier.
The next is a refractive, or lenticular lens, screen. In this type of screen, a sheet of curved lenses is placed in front of the image. This bends the light rays so that they travel multiple pathways outward and create the same multiple-view effect as rendered by an occlusive screen. The big advantage over occlusive screens is that the image is sharper and brighter due to more of the light being transmitted outwards through the clear lenticular lens rather than being heavily blocked by the opaque parallax barrier. The number of viewing angles is also considerably widened. Refractive screens are more expensive to manufacture but offer superior overall performance compared to that of a parallax barrier system.
Stepping up from these are the super multiview devices, which rely upon a methodology of extremely fast transmission rates of multiple views. The eye is simultaneously immersed in multiple images at rates much higher than the human eye can ordinarily process. Seeing both images creates the same impression as one would get from divergent eye views of the same image when delivered at a much lower refresh rate.
It also greatly reduces eyestrain from long-duration viewing by narrowing the conflict between the eye’s need for accommodation (focus upon a particular plane) and vergence (alignment towards a particular distance). These are at odds in a simulated 3D display wherein the eye’s need for accommodation wants to lock in on the flat plane of the monitor and its vergence wants to concentrate on the assumed distance of the object being simulated inside the surface of the display.
Beyond these, there are a number of exotic and free-standing 3D display technologies that are gaining acceptance as well. Volumetric displays abandon the notion of flat screen technology and produce their imagery in a genuine three-dimensional space. A volumetric display might project an image onto a selected spherical-shaped area, for example, as opposed to doing so on a two-dimensional flat plane. In this regard, they are an actual, as opposed to a simulated, three-dimensional view that can be observed and appreciated from every possible vantage point.
The display is created by lasers operating on opposing X and Y axes to trigger light in the spaces where they intersect. While these create amazing three-dimensional views, they are handicapped by their need to operate in relatively low-light environments. They also have limited color palettes available.
A close cousin of the volumetric display is the well-known holographic display. These operate on relatively similar principles but project their images in a way that they can only be seen from a limited range of viewing angles as opposed to the all-around one provided by volumetric ones. Holograms are extremely useful in medical applications due to the precise view they render.
Another intriguing area of development is found in the quest for pseudo-holographic 3D display solutions. These devices offer tremendous commercial possibilities since they are effectively a two-way 3D system. The user not only sees the 3D display but can interact with it in 3D as well. The potential applications for the gaming industry, just for starters, are immense.
The rapid maturation and cross-fertilization of these diverse approaches to 3D rendering has opened up entire new swathes of commercial possibilities. While a very large demand for 3D display technology already exists in the provision of mass entertainment, the backside of that demand is just starting to be scratched. Using 3D technology in the creation of the products later to be shown on 3D viewing platforms is still in its infancy.
Large-scale adoption of 3D displays for advertising purposes is also just coming into widespread acceptance. It is clear, however, that 3D advertising displays will eventually become the norm and current 2D placarding will be rendered obsolete.
Medical usage of 3D imaging grows every single year. The prospects for 3D interactive gaming are astonishing. On a more individual scale, the art world now has an entire third dimension to add to its established canvas of formerly 2D-limited creative expression. Already out there is a host of modern Rembrandts vigorously experimenting with three-dimensional art forms.
