Rendering, Adaptation and 3D Displays - 3DTV: Processing and Transmission of 3D Video Signals - page 149

be improved much further to allow for real-time multi-view playback from
two or three view input streams.
The current multi-view auto-stereoscopic displays on the market, which
can create from 9 up to 27 viewpoints, are mostly operable with ready-to-
display, compatible raw content in real time (i.e. pre-generated viewpoints),
but not with two or three camera-plus-depth pairs. Therefore, the 3D market
is currently, and will continue for some time to be, dominated by stereo-
scopic 3D display technologies based on passive-polarized and active-shutter
glasses technologies, while the multi-view-plus-depth rendering efficiency
and performance for auto-stereoscopic multi-view displays will continue to
improve over time.
5.4.5 Light-FieldDisplay
Active and passive stereoscopic displays as depicted in Sections 5.4.3 and
5.4.2 are the most commonly available and sold 3D display systems that
are on the consumer market. However, they can only provide the depth
feeling from a single and fixed perspective. In other words, regardless of the
observation point with respect to the display, every subject is exposed to the
same pair of stereoscopic images. As described in Section 5.4.4, the principle
of auto-stereoscopic displays is to direct different stereoscopic image pairs to
different angles from the screen surface to create motion-parallax effect, but
the most widespread types, such as the systems based on lenticular sheet or
parallax barrier, have limited spatial resolution.
Viewers are offered a sufficiently smooth and continuous view flow only
in a narrow Field of View (FoV). FoV is a crucial feature of any 3D display
technology. It refers to the emission range of a display screen. Considering
the cone, which is formed by the beams emitted from a particular spot
on the screen, the angle (openness) of it refers to the resultant FoV. Similarly,
the number of independent light-beams within the FoV that corresponds
to the angular resolution, determines the Field of Depth (FoD). Light-field
display technology is capable of creating 3D images with quasi-continuous
motion parallax in a much wider FoV as opposed to auto-stereoscopic
displays.
To display 3D image sequences properly in a realistic sense, a display
should produce and emit sufficiently many points in a given time duration
[13]. Since the FoV associated with 3D light-field displays is usually larger
than that of plano-stereoscopic displays, the number of source (input) views
that drive the display to be processed is also larger, which inherently adds
to the overall processing workload of the display.
Volumetric displays that constitute a type of such 3D displays create 3D
images through emitting or scattering the illumination from a defined point
in a three-dimensional space, rather than from a point on a planar surface. A
group of modern volumetric displays consist of non-static components, such
as the visualization area, which could be a fast rotating mirror, or any special