Coming at You! 3-D Displays Finally Seem Headed for Commercial Success
by Brian T. Schowengerdt
3-D display technology is coming of age and appears to have reached the tipping point for widespread commercial adoption.
Nowhere was this more apparent than during SID's Display Week this May, where a "Special Session on 3-D in Cinema" organized and co-chaired by Brian Berkeley (Samsung Electronics) and myself, featured six speakers at the forefront of the growing 3-D movement. Phil McNally (Dreamworks Animation), Rob Engle (Sony Pictures Imageworks), John Modell (3ality Digital), and Norman Rouse (Quantel) focused on content creation and showed stunning 3-D clips from their bodies of work, projecting them in stereo on a 25-ft.-wide screen with equipment provided by RealD. Jeff McNall (Dolby Labs) and Rod Archer (RealD) described the technical advances that are enabling the widespread conversion of theaters to 3-D.
The recent successes of 3-D movies (Hannah Montana & Miley Cyrus: Best of Both Worlds Concert Tour set Hollywood records by averaging more than $45,000 per screen during the opening weekend) and the decision of prominent moviemakers such as Steven Spielberg, Peter Jackson, and James Cameron to make 3-D movies have provided an impetus for more movie theaters to convert to digital 3-D. The number of 3-D capable theaters in the U.S. is expected to increase from the current 1500 to more than 4000 by the end of 2009 – which in turn is encouraging moviemakers to make more 3-D movies.
The term "3-D displays" encompasses a wide range of technologies, including stereoscopic, volumetric, and holographic displays. The projection systems in theaters are stereoscopic displays – meaning they present different images to right and left eyes. Why is it useful to do this? Our eyes, being separated by about 2.5 in., have slightly different vantage points and thus receive different images when viewing the same real-world scene. You can demonstrate this to yourself by lining up your thumbs, one in front of the other, and alternating between closing your right and left eyes – one thumb will appear to shift side-to-side relative to the other thumb. These "binocular disparities" between retinal images help your visual system to better estimate the distance to each thumb. If you place one thumb at arm's length and the other a few inches in front of your face, you will see large side-to-side shifts as you alternate eyes. As you bring one thumb toward the other, the disparities will decrease – all but disappearing when the thumbs meet at the same distance. We refer to this relationship between the actual distance between objects and the magnitude of binocular disparities between eye images as stereo vision, and it is one of the strongest contributors to general depth perception.
If we take pictures with two side-by-side cameras, we can capture these binocular disparities. If we later use a stereoscopic display to present the left camera image to the left eye and the right camera image to the right eye, the disparities can stimulate depth perception and give the viewer the impression that objects are in front of or behind the screen. The stereo displays in movie theaters are projection systems that have been retrofit to project alternating left and right eye views on the movie screen. By wearing special glasses that selectively filter the light reflected from the screen (with polarized lenses in RealD and IMAX 3D theaters, and special color filters in Dolby theaters) the left eye sees only the left image and the right eye only the right image.
Stereoscopic displays are the most ubiquitous "3-D" displays because they are the simplest to design, manufacture, and drive. In essence, they are two standard 2-D displays – one for the right eye and one for the left. However, this approach is limited in its ability to correctly re-create all of the depth cues present when viewing the real world.
In this special issue of Information Display, we feature four articles that discuss the limitations of stereoscopic displays, provide empirical data suggesting that they compromise performance at 3-D tasks and contribute to eye fatigue, and explore a number of holographic and volumetric display technologies that overcome these limitations.
In "Consequences of Incorrect Focus Cues in Stereo Displays," vision scientists Marty Banks and David Hoffman of UC Berkeley, engineer Kurt Akeley of Microsoft Research, and NYU neuroscientist Ahna R. Girshick discuss the physiology of the human visual system and the sensory conflicts arising from the incorrect focus cues present when viewing stereoscopic displays. They report empirical data gathered in studies of human subjects using a multi-planar volumetric display testbed that strongly support the contention that these sensory conflicts hinder performance of 3-D tasks and contribute to eye fatigue.
Holographic display technology offers the potential to reconstruct an accurate light field with accurate focus cues, but dynamic holography has been limited by the computational power and storage necessary to drive the displays. In "Refreshable Holographic 3-D Displays," Sava Tay of Stanford University and Nasser Peyghambarian of the University of Arizona describe an updateable holographic medium with memory, based on photorefractive polymers, that helps to overcome the storage challenge. In "A New Approach to Electro-Holography: Can This Move Holography into the Mainstream?" Hagen Stolle and Ralf Häussler of SeeReal Technologies describe a viewpoint-specific approach to digital holography which dramatically lowers the computational requirements to display high-resolution dynamic imagery.
Volumetric displays also can provide an accurate light field to viewers and can leverage existing 3-D graphics cards. In "Scanned Voxel Displays," co-authored by myself and colleague Eric Seibel at the University of Washington, we describe a viewpoint-specific volumetric display that can render correct focus cues for objects ranging from inches in front of the eyes to the distant horizon.
This is an exciting time to be working in 3-D. The broad adoption of today's stereo displays, coupled with the advances in holographic and volumetric displays, promises to herald a new age of 3-D display. As DreamWorks Animation CEO Jeffrey Katzenberg has proclaimed, 3-D is "the single most revolutionary change since color pictures."