Page 209 - DCAP504_Computer Graphics

Computer Graphics

Ray tracing is a method which involves creation of a geometric scene through its lighting effects .i.e.
arriving from a surface. This method was developed for modeling global illumination properties.
Following are some of the examples of ray tracing.

Secondary illumination (color bleeding) and reflection of objects from mirror.

Did you know? Ray tracing is named after its inventor by name Turner Whitted and hence known as
Whitted ray tracing.

Ray tracing is used to synthesize realistic images. It can easily produce shadows and thus can model
reflective and transparent objects. Due to its slow nature, ray tracing is used to generate realistic images,
thereby enabling it to generate realistic texture maps and environment maps which are used for
interactive rendering. This method is also used for producing very realistic types of complex shading
and lighting in spite of its conceptual simplicity.

If the movement of light is modeled in a three-dimensional scene then it is possible to produce accurate
renderings. However, this is not possible due to the computational complexity involved. As most of the
rays, which originate from the incident light do not strike the viewer’s eye and therefore, backward
tracing is done to trace the light rays which hit the eye and this is the basic idea of ray tracing.
In ray tracing, only the perfect mirror reflections are considered by a recursive ray tracer.
Some of the advantages of ray tracing are that:
1. It is simple to implement and can generate impressive visual effects.
2. It is simple to analyze the effects like reflection and shadows using ray tracing (difficulty in
simulating the algorithms is solved by using ray tracing).
13.3 Morphing

Morphing is the process used to transform (morph) one image to another image. To use morphing
techniques, you do not require the knowledge of 3-D technology. This technique finds its application in
photography, drawings, and image rendering scenes.
Morphing is widely used in motion pictures and animations where one image is changed to another
image through continuous transitions. It is generally used to depict the transformation of one person to
another person through technological means which appear bizarre and not real. This kind of depiction
is obtained by using the cross fading technique. However, today the cross fading technique has been
replaced by many computer software to develop more realistic transitions.

Cross fading morphing is a type in which you come across events where, if one face
fades, the other appears, then there is a blank screen and the other face appears
simultaneously.

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