Note for Computer Graphics - CG by Mohammad Akbal

Topics ( 8 )

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Index SNo Lesson No. 1 1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 Lesson Name Author Vetter Overview of Computer Graphics Display Devices Scan Conversion 2D Transformations Graphics Operations Interactive Devices 3D Graphics The Concept of Multimedia and GKS Abhesik Taneja Dr. Pradeep Bhatia Abhesik Taneja Abhesik Taneja Abhesik Taneja Abhesik Taneja Abhesik Taneja Abhesik Taneja Abhesik Taneja Dr. Pradeep Bhatia Dr. Pradeep Bhatia Dr. Pradeep Bhatia Dr. Pradeep Bhatia Dr. Pradeep Bhatia Dr. Pradeep Bhatia Dr. Pradeep Bhatia

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Author: Abhishek Taneja Vetter: Dr. Pradeep Bhatia Lesson: Overview of Computer Graphics Lesson No. : 01 1.0 Objectives At the end of this chapter the reader will be able to: • Describe Computer Graphics and its applications. • Describe and distinguish between Interactive and Passive Graphics. • Describe advantages of Interactive Graphics. • Describe applications of Computer Graphics. Structure 1.1 Introduction 1.2 Interactive Graphics 1.3 Passive Graphics 1.4 Advantages of Interactive Graphics 1.5 How the Interactive Graphics Display Works 1.6 Applications of Computer Graphics 1.7 Summary 1.8 Keywords 1.9 Self Assessment Questions (SAQ) 1.10 References/Suggested Readings

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1.1 Introduction The term computer graphics includes almost everything on computers that is not text or sound. Today almost every computer can do some graphics, and people have even come to expect to control their computer through icons and pictures rather than just by typing. Here in our lab at the Program of Computer Graphics, we think of computer graphics as drawing pictures on computers, also called rendering. The pictures can be photographs, drawings, movies, or simulations - pictures of things, which do not yet exist and maybe could never exist. Or they may be pictures from places we cannot see directly, such as medical images from inside your body. We spend much of our time improving the way computer pictures can simulate real world scenes. We want images on computers to not just look more realistic, but also to be more realistic in their colors, the way objects and rooms are lighted, and the way different materials appear. We call this work “realistic image synthesis”. 1.2 Interactive Graphics In interactive computer graphics user have some control over the picture i.e user can make any change in the produced image. One example of it is the ping pong game. The conceptual model of any interactive graphics system is given in the picture shown in Figure 1.1. At the hardware level (not shown in picture), a computer receives input from interaction devices, and outputs images to a display device. The software has three components. The first is the application program, it creates, stores into, and retrieves from the second component, the application model, which represents the the graphic primitive to be shown on the screen. The application program also handles user input. It produces views by sending to the third component, the graphics system, a series of graphics output commands that contain both a detailed geometric description of what is to be viewed and the attributes describing how the objects should appear. After the user input is processed, it sent to the graphics system is for actually producing the picture. Thus the graphics system is a layer in between the application program and the display hardware that effects an output transformation from objects in the application model to a view of the model.

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Applicatio n Program Applicati on Model Graphics system Figure 1.1: Conceptual model for interactive graphics The objective of the application model is to captures all the data, objects, and relationships among them that are relevant to the display and interaction part of the application program and to any nongraphical postprocessing modules. 1.3 Passive Graphics A computer graphics operation that transfers automatically and without operator intervention. Non-interactive computer graphics involves one way communication between the computer and the user. Picture is produced on the monitor and the user does not have any control over the produced picture. 1.4 Advantages of Interactive Graphics Graphics provides one of the most natural means of communicating with a computer, since our highly developed 2D and 3D pattern-recognition abilities allow us to perceive and process pictorial data rapidly and efficiently. In Many design, implementation, and construction processes today, the information pictures can give is virtually indispensable. Scientific visualization became an important field in the late 1980s, when scientists and engineers realized that they could not interpret the data and prodigious quantities of data produced in supercomputer runs without summarizing the data and highlighting trends and phenomena in various kinds of graphical representations. Creating and reproducing pictures, however, presented technical problems that stood in the way of their widespread use. Thus, the ancient Chinese proverb “a picture is worth ten thousand words” became a cliché in our society only after the advent of