Image Processing Reference
In-Depth Information
such as a computer display. Such processing lies within the realm of computer
graphics and is also called 3D graphics. Important features include determi-
nation of shapes using the laws of perspective (perspective projections) and
creation of shading and shadows using a variety of supplied methods (re-
flectivity models of the object surface, correspondence relationships between
distance and density values, characteristics related to the shape of the object
and the shape of light sources, characteristics of component materials, etc.).
(d) Creation and display of 3D images using optical and visual
effects
A variety of 3D images of types (3) and (4) as described in Section 1.2.2, such
as stereovision and holograms, can be created and displayed.
(e) Stereology
When only a small number of cross sections of the 3D object can be observed,
mainly geometric and statistical methods can be applied to whatever infor-
mation can be ascertained from them to obtain information about the 3D
space. Active research into such attempts has been ongoing over the past two
or three decades in a wide variety of applied fields, including biology, pathol-
ogy, crystallography, and mineralogy. The methodology also has been to some
extent theoretically systematized and is now called stereology. Academically,
stereology is included in a field called the science of form, and active research
continues. In recent years, advances in imaging and computer technology have
made possible the measurement of entire spaces in other areas, and so inter-
est has waned. The underlying logic remains valid, however, and there remain
cases where for some subjects information can be obtained only from only a
very limited number of cross sections, and so this remains an important basic
method. See, for example, the original articles by [Toth72, Weibel79], etc.
1.3.2 Virtual spaces as 3D digital images
True 3D images are recordings of some characteristic value for an entire 3D
space, including both the interiors and exteriors of any objects. When those
values are read into a computer, the subjects, or an overall 3D structure, are
recorded therein. Viewing such as a virtual reality (VR), one can say that
the objects (or the space) have been virtualized and now reside within the
computer. Of course, such objects are no longer restrained by the laws of
reality and can be manipulated as desired. This is an important perspective,
and presents great possibilities for VR technology applications. For example,
taking CT imaging of a human subject as a representative example of a true 3D
image, that image represents a virtualized human body within the computer.
This makes it possible to perform a number of actions that are dicult to
Search WWH ::




Custom Search