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Note for Computer Graphics - CG by Priya H

  • Computer Graphics - CG
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  • APJ Abdul Kalam Technological University - KTU
  • 4 Topics
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CS401 - COMPUTER GRAPHICS MODULE 1 SYLLABUS Basic concepts in Computer Graphics – Types of Graphic Devices – Interactive Graphic inputs – Raster Scan and Random Scan Displays. 1. Basic Concepts in Computer Graphics ● Computer Graphics involves the generation, representation, manipulation, processing or evaluation of graphic objects by a computer as well as the association of graphic object with related non-graphic information residing in computer files. ● With developments in computing technology interactive computer graphics has become an effective tool for the presentation of information in such diverse fields as science, engineering, medicine, business, industry, government, art, entertainment, advertising, education, and training. ● There is virtually no field in which graphical displays cannot be used to some advantage and that is the basic reason why application of computer graphics is so widespread. ● Typical graphics system comprises of ​a host computer with support of fast processor, large memory, frame buffer ​and ● ○ Display devices​ (color monitors), ○ Input devices ​(mouse, keyboard, joystick, touch screen, trackball) ○ Output devices ​(LCD panels, laser printers, color printers. Plotters etc.) ○ Interfacing devices ​such as, video I/O, TV interface etc. Graphic hardware can be divided into three major categories of devices: ○ Input devices ​with which the user interacts to generate necessary instruction or data for creating graphics ● ○ Display systems ​where the graphics are rendered on the monitor screen ○ Hardcopy devices ​or printers through which the tangible graphics output is produced. Applications of Computer Graphics ○ Graphical User Interfaces ∗ Major component – Window manager (multiple-window areas) ∗ To make a particular window active, click in that window (using an interactive pointing device)

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○ ∗ Interfaces display – menus & icons ∗ Icons – graphical symbol designed to look like the processing option it represents ∗ Advantages of icons – less screen space, easily understood ∗ Menus contain lists of textual descriptions & icons ∗ Multiple window, icons, menus allow a computer setup to be utilized more efficiently Presentation Graphics ∗ (Interactive) plotting in business, science and technology ∗ Used to ​produce illustrations which summarize various kinds of data. ∗ Used to produce illustrations for reports or generate slides for use with projectors. ∗ Commonly used to summarize financial, statistical, mathematical, scientific, economic data for research reports, managerial reports & customer information bulletins ∗ ○ Examples : ​Bar charts, line graphs, pie charts, surface graphs, time chart Computer Aided Design (CAD) ∗ Used in design of buildings, automobiles, aircraft, watercraft, spacecraft, computers, textiles & many other products ∗ Objects are displayed in wire frame outline form ∗ Graphics design package provides standard shapes (useful for repeated placements) ∗ Animations are also used in CAD applications ∗ Realistic displays of architectural design permits simulated “walk” through the rooms (virtual -reality systems) ○ Computer Art ∗ Used in fine art & commercial art ○ Includes artist’s paintbrush programs, paint packages, CAD packages and animation packages ○ These packages provides facilities for designing object shapes & specifying object motions. ○ ∗ ∗ Electronic painting ○ Picture painted electronically on ○ a graphics tablet (digitizer) using a stylus Morphing ○ ○ Examples : Cartoon drawing, paintings, product advertisements, logo design A graphics method in which one object is transformed into another Entertainment (animation, games, …) ∗ Movie Industry ○ Used in motion pictures, music videos, and television shows. ○ Used in making of cartoon animation films

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∗ ○ Game Industry ○ Focus on interactivity ○ Cost effective solutions ○ Avoiding computations and other tricks Education & Training ∗ Computer generated models of physical, financial and economic systems are used as educational aids. ∗ Models of physical systems, physiological systems, population trends, or equipment such as color-coded diagram help trainees understand the operation of the system ∗ ○ Specialized systems used for training applications ○ simulators for practice sessions or training of ship captains ○ aircraft pilots ○ heavy equipment operators ○ air traffic-control personnel Visualization (scientific & business) ∗ Scientific Visualization ○ Producing graphical representations for scientific, engineering, and medical data sets ∗ Business Visualization is used in connection with data sets related to commerce, industry and other non-scientific areas ∗ Techniques used- color coding, contour plots, graphs, charts, surface renderings & visualizations of volume interiors. ∗ Image processing techniques are combined with computer graphics to produce many of the data visualizations ○ Image Processing ∗ CG- Computer is used to create a picture ∗ Image Processing – apply techniques to modify or interpret existing pictures such as photographs and TV scans ∗ It is widely used in medical applications. ∗ Medical applications ∗ ○ Picture enhancements ○ Simulations of operations ○ Ultrasonics & nuclear medicine scanners 2 applications of image processing ○ Improving picture quality ○ Machine perception of visual information (Robotics)

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∗ To apply image processing methods ○ Digitize a photograph (or picture) into an image file ○ Apply digital methods to rearrange picture parts to ○ i. enhance color separations ii. Improve quality of shading Tomography – technique of X-ray photography that allows cross-sectional views of physiological systems to be displayed ○ Computed X-ray tomography (CT) and position emission tomography ( PET) use projection methods to reconstruct cross sections from digital data ○ Computer-Aided Surgery is a medical application technique to model and study physical functions to design artificial limbs and to plan & practice surgery 2. Types of Graphic Devices - ​Non Interactive Computer Graphics - Interactive Computer Graphics ● Non Interactive Computer Graphics ○ In ​non interactive computer graphics ​otherwise known as ​passive computer graphics​, the observer has no control over the image. ○ Familiar examples of this type of computer graphics include the titles shown on TV and other forms of computer art. ● Interactive Computer Graphics ○ Interactive Computer Graphics involves a two way communication between computer and user. ○ Here the observer is given some control over the image by providing him with an input device for example the video game controller of the ping pong game. This helps him to signal his request to the computer. The computer on receiving signals from the input device can modify the displayed picture appropriately. To the user it appears that the picture is changing instantaneously in response to his commands. He can give a series of commands, each one generating a graphical response from the computer. In this way he maintains a conversation, or dialogue, with the computer. ○ Interactive computer graphics affects our lives in a number of indirect ways. ○ For example, it helps to train the pilots of our airplanes. We can create a ​flight simulator ​which may help the pilots to get trained not in a real aircraft but on the grounds at the control of the flight simulator. The flight simulator is a mockup of an aircraft flight deck, containing all the usual controls and surrounded by screens on which we have the projected computer generated views of the terrain visible on take off and landing. Flight simulators have many advantages over the real

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