VISUALIZATION OF 3D GRAY-TONE IMAGES - Fundamentals of Three-Dimensional Digital Image Processing - page 226

Fig. 7.11. Wine glasses generated by ray tracing. Part of checkerboard pattern
seen through a glass in distorted by refraction. A brighter part on the top of a
glass is generated by direct reflection of a virtual light source. Images of parts of
other glasses are observed on a surface (“reflection image”) and on the floor of
the glass. This shows a typical example of photorealistic rendering in early 1980s
[Horiuchi87, Kurashige86].
than one object exists in 3D space. By using this method, we can render an
image of objects reflected on the surface of other objects and objects behind
other transparent object.
As explained above, this procedure is implemented by tracing light paths
inversely from the viewpoint toward an object and a light source. Note that
real light radiates from a light source toward objects and repeats reflection
and/or refraction before reaching our eyes. The above procedure is called ray
tracing [Whitted80, Watt98]. This is a type of simulation of an optical phe-
nomenon in the neighborhood of a surface of an object and a border between
adjacent objects. Really photorealistic rendering has become possible by this
method. It contributed much to raise the evaluation of computer graphics. A
large number of papers have been published on improvement of the ray trac-
ing and its applications. An example of its application is shown in Fig. 7.11.
However, the ray tracing explained above is not always suitable as a main
topic for this chapter.