Page 38 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Lab on Computer Graphics

Notes 13. The term computer graphics has been used in a broad sense to describe “almost everything
on computers that is not text or sound”.

( a) True (b) False
14. A cathode ray tube (CRT) is not a specialized vacuum tube in which images are produced
when an electron beam strikes a phosphorescent surface.
( a) True (b) False
15. Resolution indicates the maximum number of points that cannot be display without overlap
on the CRT.
( a) True (b) False

2.8 Summary

• The term computer graphics describes any use of computers to create and manipulate
images. Graphics can be two- or three-dimensional; images can be completely synthetic
or can be produced by manipulating photographs.
• Computer Graphics systems could be active or passive. In both cases, the input to the
system is the scene description and output is a static or animated scene to be displayed.
• The term computer graphics has been used in a broad sense to describe “almost everything
on computers that is not text or sound”.
• Visualization is a technique for creating images, diagrams, or animations to communicate a
message. Visualization through visual imagery has been an effective way to communicate
both abstract and concrete ideas.
• Data visualization is a related subcategory of visualization dealing with statistical graphics
and geographic or spatial data (as in thematic cartography) that is abstracted in schematic
form.

• A CRT is an evacuated glass tube. An electron gun at the rear of the tube produces a beam
of electrons which is directed towards the front of the tube (screen).

• Colour monitors for desktop microcomputers are based on cathode ray tubes (CRTs) or
back-lighted flat-screen technologies.

2.9 Keywords

Boolean Set: Boolean algebra also deals with other values on which Boolean operations can
be defined, such as sets or sequences of bits. However, Boolean algebra is unlike many other
systems of algebra in that it obeys exactly the same laws (educational properties), neither more
nor fewer, no matter which of these other values are employed. Much of the subject can therefore
be introduced without reference to any values besides 0 and 1.
Bump Mapping: Bump mapping is a technique in computer graphics for simulating bumps and
wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the
object and using the perturbed normal during lighting calculations.

Pixel: In digital imaging, a pixel, or palette, (picture element) is a physical point in a raster
image, or the smallest, addressable element in a display device; so it is the smallest, controllable
element of a picture represented on the screen.
Texture Mapping: A texture map is applied (mapped) to the surface of a shape or polygon. This
process is akin to applying patterned paper to a plain white box. Every vertex in a polygon is

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