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Neil A. Dodgson
Most of the perceptual cues we use to visualize 3D structures are available in 2D projections. This is why we can make sense of photographs and images on a television screen, at the cinema, or on a computer monitor. Such cues include occlusion, perspective, familiar size, and atmospheric haze.
Four cues are missing from 2D media: stereo parallax—seeing a different image with each eye; movement parallax—seeing different images when we move our heads; accommodation—the eyes' lenses focus on the object of interest; and convergence—both eyes converge on the object of interest. All 3D display technologies ( stereoscopic displays) provide at least stereo parallax. Autostereoscopic displays provide the 3D image without the viewer needing to wear any special viewing gear.
Gregg E. Favalora
Volumetric displays produce volume-filling three-dimensional imagery. Each volume element or voxel in a 3D scene emits visible light from the region in which it appears. Given their ability to project volume-filling autostereoscopic imagery, these displays are being adopted in fields as diverse as medical imaging, mechanical computer-aided design, and military visualization. The author uses the term autostereoscopic to describe a display property that lets observers experience a 3D effect without requiring any additional eyewear.
Vendors are developing software that lowers the barrier to adoption by providing compatibility with new and legacy applications. At least one firm is developing a display-independent visualization environment with the aim of accelerating the adoption of 3D displays overall.
The widespread adoption of volumetric 3D displays requires the ability to integrate tightly into today's visualization software. Given that ability, developers can deploy volumetric displays across the fields where they are most critically needed.
Chris Slinger, Colin Cameron, and Maurice Stanley
Invented in 1947 by Dennis Gabor, holography—from the Greek holos, for whole—is a 3D display technique that involves using interference and diffraction to record and reconstruct optical wavefronts. Holography's unique ability to generate accurately both the amplitude and phase of light waves enables applications beyond those limited by the light manipulation capabilities of lens- or mirror-based systems.
Computer-generated holography avoids the interferometric recording step in conventional hologram formation. Instead, a computer calculates a holographic fringe pattern that it then uses to set the optical properties of a spatial light modulator, such as a liquid crystal microdisplay. The SLM then diffracts the readout light wave, in a manner similar to a standard hologram, to yield the desired optical wavefront.
Although CGH-based display systems can be built today, their high cost makes them impractical for many applications. However, as compute power and optical hardware costs decrease, CGH displays will become a viable alternative in the near future.
Benjamin Watson and David Luebke
Building a wall-size display that supports human visual acuity during close-up viewing would require approximately 670 megapixels, with 190 dpi. A wall display that supports the eye's hyperacuities would require roughly 165 gigapixels at 3,000 dpi. This is more than 10,000 times the pixels available in today's largest displays.
Obviously, we won't see such displays for a long time. In the meantime, researchers are pursuing a more realistic and still extremely useful challenge: printer-resolution (600 dpi) wall displays updated at 240 Hz, requiring 7.2 gigapixels.
The real challenge of these displays is bandwidth, to which the authors offer one innovative solution: adaptive frameless rendering. This approach abandons the traditional concepts of animation as a sequence of images, or frames, and departs from viewing images as temporally coherent grids of samples, or pixels. Instead, it generates samples selectively when and where they are needed.
Mary Lou Jepsen
Most development efforts toward the ultimate display technology focus on the initial demonstration, with little consideration of the demo's manufacturability. Efforts to make the product commercially available generally hit tremendous obstacles and die out within a few years.
Unfortunately, researchers who build and successfully demonstrate prototypes usually are unaware of the difficulties involved in bringing them to market. In many cases, these displays remain prototypes and will never make it to become a product. The hard part of a manufacturable solution is the cost: Bandwidth, video encoding, circuit design and yield, display uniformity, reliability, and image quality all take their toll.
When developing the ultimate display, an organization should focus on the manufacturing pipeline, leveraging its existing capacity to get from demo to product more quickly.