Chapter-2 Overview of Graphics Systems Topics: Topics: Video-display system Video-display system Rater Scan systems Rater Scan systems Random scan systems Random scan systems Graphic monitors and workstations Graphic monitors and workstations Input devices Input devices Hard-copy devices Hard-copy devices Graphics Software Graphics Software

Video-Display Devices Refresh Cathode-Ray Tunes Fig.2-2 Basic design of a magnetic-deflection CRT

Video-Display Devices Refresh Cathode-Ray Tunes Fig.2-3 Operation of an electron gun with an accelerating anode.

Video-Display Devices Refresh Cathode-Ray Tunes Fig.2-4 Electrostatic deflection of the electron beam in a CRT

Video-Display Devices Illumination of phosphor spots on back of CRT

Video-Display Devices Fig.2-7 A raster –scan system displays an object as a set of discrete points across each scan line.

Video-Display Devices Video-Display Devices Note at the Interlace mechanism of display: display the even lines in 1/60 of a second and then display the odd lines in next 1/60 seconds.

Video-Display Devices Fig.2-9 A random-scan system draws the component lines of an object in any order specified.

Video-Display Devices Fig.2-10 Operation of a delta-delta, shadow-mask CRT. Three electron guns, aligned with the triangular color-dot patterns on the screen, are directed to each dot triangle by a shadow mask.

Flat panel displays Fig.2-11 Basic design of a plasma-panel display device. Applying voltages to a pair of horizontal and vertical conductors causes the gas at the intersection of two conductors to break down into a glowing plasma of electron and ions.

Flat panel displays A plasma-panel display with a resolution of 2048 x 2048 and a screen diameter of 1.5 meters.

Flat panel displays Basic design of a thin-film electro-luminescent display device.

Liquid-crystal displays (LCD) Laptops use LCD display mechanism with different resolutions and different number of colors.

How a Liquid-crystal displays (LCD) works. By twisting the LCD Nematics, the polarized light passed through the horizontal conductor will twist and pass through the vertical conductor. This is how one pixel Becomes visible. To turn off a pixel, the LCD Nematics will be Forced to become Parallel. This is done by applying A voltage to both Horizontal and vertical conductors. The screen is refreshed in the rate of 60 frames per second As in emissive devices.

Stereoscopic and Virtual-Reality Systems Fig.2-19 Viewing a stereoscopic projection.

Stereoscopic and Virtual-Reality Systems Fig.2-20 A stereoscopic viewing pair.

Stereoscopic and Virtual-Reality Systems Fig.2-21 Glasses for viewing a stereoscopic scene and an infrared synchronizing emitter.

Stereoscopic and Virtual-Reality Systems Fig.2-22 A headset used in virtual-reality system

Interacting with a virtual-reality environment. Use of head-set, data gloves and a set of cords to transfer the data to a host computer.

Fig.2-24 An ultrasound tracking device used with stereoscopic glass to track head position.

Raster-scan system Fig.2-25 The architecture of a simple raster graphics system.

Raster-scan system Fig.2-26 Architecture of a raster system with a fixed portion of the system memory reserved for the frame buffer.

Raster-scan system

Fig.2-28 Basic video-controller refresh operations.

Raster-scan system Fig Architecture of a raster-graphics system with a display processor.

How characters are displayed on a Raster-scan system Limits in size, font type, etc. Possibilities to save fonts of different Sizes without the need to save a large bitmap.

Random-scan systems Fig.2-32 Architecture of a simple random-scan system.

Graphics monitors and work-stations Fig.2-35 A very high-resolution (2560 x 2048) color monitor for Air traffic control application.

Graphics monitors, A Media-Wall Fig.2-36 The Media-Wall: A multi-screen display system. An image displayed on a 3-by-3 array of monitors. Applications in Airports, and places that we need to have live announcements.

Graphics monitors and work-stations

Multiple work-stations for a CAD group.

An artist’s work-station, featuring a color raster monitor, graphic tablet with hand cursor, a light tablet.

Fig.2-42, Z mouse is used to displace objects in 3D space. The Z mouse features 3 buttons, a mouse ball underneath, a thumbwheel on the side, and a track ball on top.

Digitizers. Fig.2-46, The Summa-Sketch III desktop tablet with a 16 button hand cursor.

Digitizers. The Microgrid III tablet with 16 button hand cursor, designed for digitizing larger drawings.

Digitizers. Fig.2-48 The NotePad desktop tablet with stylus. This devise is used for On line signature input, On line handwriting input And On-line drawing input to a PC. Some models of it can sense pressure, speed, and the direction of pressure. This is a perfect devise for on line signature recognition.

Digitizers. Fig.2-49 An artist’s digitizer system, with a pressure sensitive Cordless stylus.

Digitizers. Fig.2-50 A 3D digitizing system for use with Apple Macintosh computers.

Image Scanners Fig.2-52 (Right) Drum scanner with a selectable resolution from 50 to 4000 dots per inch.

Scanner Fig A large floor-model scanner used to scan architectural and engineering drawings up to 40 inches wide and 100 feet long.

Touch Screens Fig Plasma panels with touch screens.

How does a touch screen works. An optical touch panel, showing the arrangement of infrared LED units and detectors around the edges of the frame.

Light Pens Fig.2-56 A light pen activated with a button switch.

A speech-recognition system

Hard copy devices A picture generated on a dot-matrix printer. Note how the density of the dot patterns can be varied to produce light and dark areas.

Hard copy devices Fig.2-61 Floor model, ink-jet color printers that use variable dot size to achieve an equivalent resolution of 1500 to 1800 dots per inch.

Hard copy devices used to print large posters An electrostatic printer that can display 400 dots per inch.

Pen Plotters Fig.2-63, A desk-top pen plotter with a resolution of mm.

Pen Plotters Fig.2-64 A large, roll-feed pen plotter with automatic multicolor 8-pen charger and a resolution of mm.

Graphics Software, Coordinate representation. Note at different levels of transformation before an object is actually displayed on monitor.