Graphics Systems

Dr. Alexander G. Gee

Basic Graphics System

Output device Input devices Image formed in FB
Institute for Visualization and Perception Research
University of Massachusetts Lowell

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A Graphics System
Output Devices Modern Video Connections Screen Properties Input Devices Imaging Systems

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Output Devices
CRT Displays LCD Displays Plasma Displays Projectors Rear-Projectors Inkjet Printers Laser Printers

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Magnetic-Deflection CRT
Hearn and Baker 2004 Computer Graphics with OpenGL 3rd Edition, Pearson Eduction, Inc.
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Operation of a CRT Electron Gun
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Electrostatic Deflection within a CRT
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SAGE Vector Graphics

Maury Markowitz 2003 SAGE (Semi Automatic Ground Environment) control room 1950s 1980s
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CRT Shadow-Masks

Electron Guns Section of a Shadow Mask
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CRT - Cathode Ray Tube

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Shadow-Mask vs. Aperture Grille
How Stuff Works 2005 How Computer Monitors Work
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Wikipedia 2004 Samsung SyncMaster 755DFX & ViewSonic GraphicSeries GT775 V
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Drawing on a Raster-Scan System
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Progressive Raster-Scan Lines
How Stuff Works 2000 How Television Works
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Interlaced Raster-Scan Lines
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Monochrome Monitor 1984

Apple Computer, Inc. 1984 Apple II 12 Monochrome Monitor
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Color Monitor 1986

Apple Computer, Inc. 1986 Apple IIe 12 AppleColor RGB Monitor
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24 Widescreen Display

Sony Electronics, Inc. 2000 GDMFWCRT Monitor
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Flat Panel Displays

Plasma Displays Organic Light-Emitting Diode Displays (OLEDs) Liquid Crystal Displays (LCDs) Digital Light Processing (DLPs) Liquid Crystal on Silicon (LCoSs) Surface-Conduction Electron-Emitter Displays (SEDs) Field Emission Displays (FEDs) Nano-Emissive Display (NEDs)
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Plasma Display Illustration
Computer Desktop Encyclopedia 2004 The Computer Language Co. Inc.
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Plasma Display

Pioneer Electronics, Inc., PDP-504CMX, 50 Professional Plasma Display.
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Plasma Display Simplified
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Thin-Film Electroluminescent Display
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Monochrome EL Display

Planar Systems, Inc. 2003 EL Displays
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OLED - Organic Light-Emitting Diode

Samsung OLED Screen

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LCD - Liquid Crystal Display
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LCD Illustration of On / Off States
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LCD Pixels

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LCD Liquid-Crystal Display
Apple Computer, Inc. Cinema HD Display
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LCD Projector

The Projector Pros 2004 LCD Flat Panel Displays Projector Technologies
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DLP Digital Light Processing
DLP Texas Instrument 2005 1-Chip DLP Processor
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1-Chip DLP Projector

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3-Chip DLP Projector

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LCOS Liquid Crystal on Silicone
The Projector Pros 2004 LCoS Projector Technology Information Liquid Crystals on Silocone
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Rear-Projection Screens

The Projector Pros 2004 Learn About Rear Projection Televisions

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Multi-Projector Graphics Wall
Visbox, Inc, 2005 VisWall
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Multi-Panel Graphics Wall
Digital Tiger, Inc. 2005 Zenview Atlas 19S & Powerscape HD
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Head Mounted Display Systems
5DT HMD 800 & Cybermind Nederland hi-Res900 & H3D Video Eyewear
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CAVE VR Environment

NCSA 2000 Cave VR Environnent VR Media Lab, Aalborg University 2004 Cave
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Electronic Paper

Bistable flat panel displays e-ink Displays Gyricon Displays Iridigm Displays Magink Displays

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Modern Video Connections
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Standard Video Adapter

1: Red out 2: Green out 3: Blue out 4: Unused 5: Ground
6: Red return (ground) 7: Green return (ground) 8: Blue return (ground) 9: Unused 10: Sync return (ground)
11: Monitor ID 0 in 12: Monitor ID 1 in or data from display 13: Horizontal Sync out 14: Vertical Sync 15: Monitor ID 3 in or data clock
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Single Link DVI

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Dual Link DVI

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Screen Properties

Raster Pixels Frame Buffers
Screen Size Screen Resolution Aspect Ratio Screen Depth Human Vision

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The Screen
Size Resolution Aspect Ratio

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Measuring a Display Screen
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Common Screen Resolutions
Computer Standard CGA QVGA EGA VGA SVGA XGA WXGA SXGA UXGA WUXGA WQXGA Resolution 25601600 4:3 approx. 5:3 4:3 4:3 4:3 15:9 5:4 4:3 16:10 16:10 Ratio 16:10 Pixels 64K 77K 224K 307K 480K 786K 983K 1.3M 1.9M 2.3M 4.1M
Wikimedia Foundation, Inc. 2006 Wikipedia
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Visually Comparing Resolutions

1280 x 1024

2560 x 1600
Patrick G. Durland 2005 Wikipedia: Video Standards
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Aspect Ratios

4:3 16:9

2.39:1

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Multiple Video Walls

Draper, Inc. 2005 VideoWalls
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Removing Display Edges

Draper, Inc. 2005 Zero Edge Framing System
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Multi-High Resolution Displays

RGB, Inc. 2005 SuperWall

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Light & Human Vision

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Human Vision

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Light is the part of the electromagnetic spectrum that causes a reaction in our visual systems Generally these are wavelengths in the range of about 350-750 nm (nanometers) Long wavelengths appear as reds and short wavelengths as blues

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Electromagnetic Waves
Levine 1985 Vision of Man and Machine
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Luminance and Color Images

Luminance Image

Monochromatic Values are gray levels Analogous to working with black and white film or television

Color Image

Has perceptional attributes of hue, saturation, and lightness Do we have to match every frequency in visible spectrum? No!

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Additive and Subtractive Color

Additive color

Form a color by adding amounts of three primaries
CRTs, projection systems, positive film
Primaries are Red (R), Green (G), Blue (B)

Subtractive color

Form a color by filtering white light with cyan (C), Magenta (M), and Yellow (Y) filters
Light-material interactions Printing Negative film

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The Human Eye
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Human Retina

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Human Cones and Rods

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Human Cone Response

Bowmaker & Dartnall 1980 Visual pigments of rods and cones in a human retina J. Physiol. 298: pp 501-51
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Frame Buffers

Resolution & Depth

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Vector Graphics

System Memory

Video Controller

Monitor

System Bus

I/O Devices

Hearn & Baker 2004 Computer Graphics
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Raster

Pixels

Frame Buffer

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Display Memory

Display Processor
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Mapping Frame Buffer

Display Surface
Hill 2001 Computer Graphics using OpenGL
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Color Frame Buffers and the Monitor
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Screen Depth

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Indexed Colors

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Direct Colors

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Display Depths

Indexed Color
1-bit (2 colors) monochrome 2-bits (4 colors) CGA 4-bits (16 colors) EGA & higher resolution VGA 8-bits (256 colors) lower resolution VGA & SVGA

Direct Color

HiColor
15-bits (5-bits or 32 levels per red/green/blue) 32,768 16-bits (5-bits for red & blue, but 6-bits or 64 levels for green)

Truecolor

24-bits (8-bits per red/green/blue) 16.7 distinct colors

32-bit Color

34-bits (24-bits for color & 8-bits for alpha)

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Input Devices

Keyboards

Qwerty

Pointers

Mice Pens

Manipulators

3D Plotters Motion Tracking

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Kingston Computer 2006 Keyboards / The Human Solution 2003 DataHand & Ergodex
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Mice & Trackballs

Doug Englebarts 1963 Mouse / Kingston Computer 2006 Mice & Trackball
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Wacom Technology 2006 Cintiq 21UX & Intuos3 12x19 & TabletPC Hardware
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Gesture Systems

FingerWorks 2002 iGesture
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3D Scanners

3D Scanner Ltd., 2005 Freedom Robot CMM / Inition Ltd., 2005 Microscribe G2 / HandyScan 3D 2005 HandyScan
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Motion Tracking

Inition Ltd., 2005 Ascension SpacePad & Gypsy4 & Monkey2
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Imaging Systems

Camera Specification Image Formation Pinhole Camera Synthetic Camera Model Ray Tracing

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Camera Specification

Six degrees of freedom

Position of center of lens Orientation
Lens Film size Orientation of film plane

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Image Formation
In computer graphics, we form images which are generally two dimensional using a process analogous to how images are formed by physical imaging systems
Cameras Microscopes Telescopes Human visual system

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Elements of Image Formation
Objects Viewer Light source(s) Attributes that govern how light interacts with the materials in the scene Note the independence of the objects, the viewer, and the light source(s)

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Pinhole Camera
Use trigonometry to find projection of point at (x,y,z) xp= -x/z/d yp= -y/z/d zp = d
These are equations of simple perspective
Angel 2006 Interactive Computer Graphics
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Pinhole Camera Views

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Synthetic Camera Model

projector
p image plane projection of p center of projection
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Real vs. Synthetic Camera Models
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Ray Tracing and Geometric Optics
One way to form an image is to follow rays of light from a point source finding which rays enter the lens of the camera. However, each ray of light may have multiple interactions with objects before being absorbed or going to infinity.

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Geometric Pipeline

Vertices

Vertex Processor

Clipper Assembler

Rasterizer

Framgment Processor

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Graphics Programming Library
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