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Computer Graphics is a branch of Computer Science, but its appeal reaches far beyond it.◦ In its short lifetime, computer graphics has

attracted some of the most creative people in the world to its fold.

◦ They come from all disciplines -- art, science, music, …

◦ In fact, since the excitement and diversity of computer graphics can best be conveyed by consideration of its applications, let us take a look at several in more detail.

Chpater 1 -- Introducing: Computer Graphics 2

Computer graphics is used today in many different areas of industry, business, government, education, and entertainment.

The list is enormous, and is growing rapidly as computers with graphics capabilities become commodity products.

Here is a brief look at some of these areas:

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User Interfaces

Interactive plotting in business, science, and technology

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Cartography

Medicine

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Computer-aided drafting and design Multimedia textbooks

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Simulation and animation for scientific visualization and entertainment.


This book concentrates on fundamental principles and techniques that were derived in the past and are still applicable today -- and generally will be applicable in the future.

It is easier to chronicle the changes in hardware than software, since hardware changes have had a greater influence on how the field has developed. Thus we will begin with hardware.

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Two basic display types◦ Vector displays and ◦ Raster displays

Both are based on Cathode Ray Tubes (CRT’s) which we will see in Chapter 4.

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Vector displays were developed in the mid-sixties and in common use until the mid eighties.◦ Characters were made up of a sequence of

vectors or strokes. This technique was also called a random scan

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Raster displays were developed in the early seventies.◦ it was based on television technology, and

contributed more to the growth of the field than any other technology.


◦ The complete image on a raster display is formed from the raster, which is a set of horizontal scan lines, each a row of individual pixels


◦ Since, in the raster system the entire grid of pixels must be stored explicitly, the availability of inexpensive solid-state random-access memory (RAM) for bitmaps in the early seventies was the breakthrough needed to make raster graphics the dominant hardware technology.

◦ Other Defs: bitmap pixmap frame buffer

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Advantages of raster over vector:◦ lower cost◦ the ability to fill areas with solid colors or

patterns.

Disadvantages:◦ The discrete nature of pixel representation.

This produces jagged lines (aliasing)◦ Scan conversion is needed◦ Vector displays produce continuous smooth

lines and curves.

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A wide range of input devices have been developed.

Basic:◦ keyboard, mouse, joystick, trackball,…

Advanced: ◦ 3D input devices with high degrees of freedom,

and ones with feedback.


It used to be low-level and device dependent packages supplied by the vendor, making it very difficult to port the software.

We have now moved to high-level device independent packages, which allow much easier porting of software.


Graphics Software Standards:◦ CORE -- 3D Core Graphics Systems -- a

specification produced by an ACM SIGGRAPH committee in 1977.

◦ GKS - Graphical Kernel System -- (1985) cleaned up and implemented the 2D portion of CORE.

◦ GKS-3D (1988) -- implemented CORE’s 3D portions. Permitted the grouping of primitives (such as

lines, polygons, and character strings -- and their attributes) into collections.

These collections could not be nested.


◦ PHIGS - Programmers Hierarchical Interactive Graphics System (1988) PHIGS also supports a retained database of

structures, and automatically updated the screen when the database had been altered.

◦ PHIGS+ (1992) added features for photorealistic rendering.

◦ Other standards Postscript X-Windows OpenGL PEX

◦ The copyright of this book.

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◦ Graphics provides one of the most natural means of communicating with a computer, since our 2D and 3D pattern recognition abilities

allow us to perceive and process data rapidly and efficiently.

◦ Interactive computer graphics permits extensive, high-bandwidth user-computer interaction. Such interactions significantly enhance our ability

to understand data, to perceive trends, and to visualize real or imaginary objects.

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The high-level conceptual framework shown here can be used to describe almost any interactive graphics system

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The three major parts of the framework are:◦ Application Modeling

Calculating what is to be displayed◦ Displaying the Model

Calling the graphics API routines◦ Interaction Handling

Handling user interaction, which will change the model, and therefore the display.

typically an event driven loop

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Graphical interfaces have replaced textual interfaces as the standard means for user-computer interaction.

Until the late eighties, the bulk of computer-graphics applications dealt with 2D objects; 3D applications were relatively rare.

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The spectacular progress of VLSI semiconductor technology also led to the explosive growth of 3D accelerators and 3D applications.

Images and animations are no longer merely illustrations in science and engineering -- they have become part of the content of science and engineering and are influencing how scientists and engineers conduct their daily work.

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