A computer graphics system is a computer system; as such, it must have all the components of a general-purpose computer system. Let us start with the high-level view of a graphics system, as shown in the block diagram in Figure 1.1(a). There are six major elements in the Graphic system:
1. Input devices
2. Central Processing Unit (CPU)
3. Graphics Processing Unit (GPU)
4. Memory
5. Frame buffer
6. Output devices
This model is general enough to include workstations and personal computers, interactive game systems, mobile phones, GPS systems, and sophisticated image generation systems. Although most of the components are present in a standard computer, it is the way each element is specialized for computer graphics that characterizes this diagram as a portrait of a graphics system.
Applications of Computer Graphics
The development of computer graphics has been driven both by the needs of the user community and by advances in hardware and software. The applications of computer graphics are many and varied; we can, however, divide them into four major areas:
a) Display of information
b) Design
c) Simulation and animation
d) User interfaces
Although many applications span two or more of these areas, the development of the field was based on separate work in each.
Display of Information
Classical graphics techniques arose as a medium to convey information among people. Although spoken and written languages serve a similar purpose, the human visual system is unrivaled both as a processor of data and as a pattern recognizer. More than 4000 years ago, the Babylonians displayed floor plans of buildings on stones. More than 2000 years ago, the Greeks were able to convey their architectural ideas graphically, even though the related mathematics was not developed until the Renaissance.
Today, the same type of information is generated by architects, mechanical designers, and drafts-people using computer-based drafting systems. For centuries, cartographers have developed maps to display celestial and geographical information. Such maps were crucial to navigators as these people explored the ends of the earth; maps are no less important today in fields such as geographic information systems. Now, maps can be developed and manipulated in real time over the Internet.
Over the past 100 years, workers in the field of statistics have explored techniques for generating plots that aid the viewer in determining the information in a set of data. Now, we have computer plotting packages that provide a variety of plotting techniques and colour tools that can handle multiple large data sets. Nevertheless, it is still the human‘s ability to recognize visual patterns that ultimately allows us to interpret the information contained in the data. The field of information visualization is becoming increasingly more important as we have to deal with understanding complex phenomena from problems in bioinformatics to detecting security threats. Medical imaging poses interesting and important data-analysis problems. Modern imaging technologies in the field of medicine—such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and positron-emission tomography (PET)—generate three-dimensional data that must be subjected to algorithmic manipulation to provide useful information.
Design
Professions such as engineering and architecture are concerned with design. Starting with a set of specifications, engineers and architects seek a cost-effective and esthetic solution that satisfies the specifications. Design is an iterative process. Rarely in the real world is a problem specified such that there is a unique optimal solution. Design problems are either overdetermined, such that they possess no solution that satisfies all the criteria; much less an optimal solution, or underdetermined, such that they have multiple solutions that satisfy the design criteria. Thus, the designer works in an iterative manner. a possible design is generated, tested it, and then the results are used as the basis for exploring other solutions.
The power of the paradigm of humans interacting with images on the screen of a CRT was recognized by Ivan Sutherland over 40 years ago. Today, the use of interactive graphical tools in computer-aided design (CAD) pervades fields such as architecture and the design of mechanical parts and of very-large-scale integrated (VLSI) circuits. In many such applications, the graphics are used in a number of distinct ways. For example, in a VLSI design, the graphics provide an interface between the user and the design package, usually by means of such tools as menus and icons. In addition, after the user produces a possible design, other tools analyze the design and display the analysis graphically.
Simulation and Animation
Once graphics systems evolved to be capable of generating sophisticated images in real time, engineers and researchers began to use them as simulators. One of the most important uses has been in the training of pilots. Graphical flight simulators have proved both to increase safety and to reduce training expenses. The use of special VLSI chips has led to a generation of arcade games as sophisticated as flight simulators. Games and educational software for home computers are almost
as impressive as the flight simulators. The success of flight simulators led to the use of computer graphics for animation in the television, motion-picture, and advertising industries. Entire animated movies can now be made by computer at a cost less than that of movies made with traditional hand-animation techniques. The use of computer graphics with hand animation allows the creation of technical and artistic effects that are not possible with either alone. Whereas computer animations have a distinct look, we can also generate photorealistic images by computer. Images that we see on television, in movies, and in magazines often are so realistic that we cannot distinguish computer-generated or computer-altered images from photographs.
The field of virtual reality (VR) has opened up many new horizons. A human viewer can be equipped with a display headset that allows her to see separate images with her right eye and her left eye so that she has the effect of stereoscopic vision. In addition, her body location and position, possibly including her head and finger positions, are tracked by the computer. She may have other interactive devices available, including force-sensing gloves and sound. She can then act as part of a computer-generated scene, limited only by the image-generation ability of the computer. For example, a surgical intern might be trained to do an operation in this way, or an astronaut might be trained to work in a weightless environment.
User Interfaces
Our interaction with computers has become dominated by a visual paradigm that includes windows, icons, menus, and a pointing device, such as a mouse. From a user‘s perspective, windowing systems such as the X Window System, Microsoft Windows, and the Macintosh Operating System differ only in details. More recently, millions of people have become users of the Internet. Their access is through graphical network browsers, such as Firefox, Chrome, Safari, and Internet Explorer that use these same interface tools. We have become so accustomed to this style of interface that we often forget that what we are doing is working with computer graphics. Although we are familiar with the style of graphical user interface used on most workstations, advances in computer graphics have made possible other forms of interfaces.
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