basic graphics system - computer science | umass … institute for visualization and perception...

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Graphics Systems

Dr. Alexander G. Gee

page 2Institute for Visualization and Perception Research University of Massachusetts Lowell

Basic Graphics System

Input devices

Output device

Image formed in FB

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A Graphics System

Output Devices

Modern Video Connections

Screen Properties

Input Devices

Imaging Systems


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.


Operation of a CRT Electron Gun


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Electrostatic Deflection within a CRT



SAGE Vector Graphics

Maury Markowitz 2003 SAGE (Semi Automatic Ground Environment) control room 1950s – 1980s

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CRT Shadow-MasksSection of a

Shadow MaskElectron

Guns



CRT - Cathode Ray Tube


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Shadow-Mask vs. Aperture Grille

How Stuff Works 2005 How Computer Monitors Work


Shadow-Mask vs. Aperture Grille

Wikipedia 2004 Samsung SyncMaster 755DFX & ViewSonic GraphicSeries GT775 V

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Drawing on a Raster-Scan System



Progressive Raster-Scan Lines

How Stuff Works 2000 How Television Works

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Interlaced Raster-Scan Lines

How Stuff Works 2000 How Television Works


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


24” Widescreen Display

Sony Electronics, Inc. 2000 GDMFW900 24” CRT 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)


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.


Plasma Display Simplified


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Thin-Film Electroluminescent Display



Monochrome EL Display

Planar Systems, Inc. 2003 EL Displays

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OLED - Organic Light-Emitting Diode

Samsung 2005 40” OLED Screen


LCD - Liquid Crystal Display


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LCD Illustration of On / Off States



LCD Pixels


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LCD – Liquid-Crystal Display

Apple Computer, Inc. 2004 30” Cinema HD Display


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


1-Chip DLP Projector


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3-Chip DLP Projector



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


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


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


Electronic Paper

Bistable flat panel displays

e-ink Displays

Gyricon Displays

Iridigm Displays

Magink Displays

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Modern Video Connections



Standard Video Adapter


15: Monitor ID 3 inor data clock 10: Sync return (ground) 5: Ground

14: Vertical Sync 9: Unused 4: Unused

13: Horizontal Sync out 8: Blue return (ground) 3: Blue out

12: Monitor ID 1 inor data from display 7: Green return (ground) 2: Green out

11: Monitor ID 0 in 6: Red return (ground) 1: Red out

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Single Link DVI



Dual Link DVI


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Screen Properties

Raster Pixels Frame Buffers

Screen Size

Screen Resolution

Aspect Ratio

Screen Depth

Human Vision


The Screen

SizeResolutionAspect Ratio

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Measuring a Display Screen



Common Screen Resolutions

4.1M16:102560×1600WQXGA2.3M16:101920×1200WUXGA1.9M4:31600×1200UXGA1.3M5:41280×1024SXGA983K15:91280×768WXGA786K4:31024×768XGA480K4:3800×600SVGA307K4:3640×480VGA224Kapprox. 5:3640×350EGA77K4:3320×240QVGA64K16:10320×200CGA

PixelsRatioResolutionComputer Standard

Wikimedia Foundation, Inc. 2006 Wikipedia

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Visually Comparing Resolutions

Patrick G. Durland 2005 Wikipedia: Video Standards

2560 x 1600

1280 x 1024


Aspect Ratios


4:316:9

2.39:1

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Multiple Video Walls

Draper, Inc. 2005 VideoWalls


Removing Display Edges

Draper, Inc. 2005 Zero Edge Framing System

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Multi-High Resolution Displays

RGB, Inc. 2005 SuperWall


Light & Human Vision

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Human Vision


Light

Light is the part of the electromagnetic spectrum that causes a reaction in our visual systemsGenerally 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


Luminance and Color Images

Luminance ImageMonochromatic Values are gray levelsAnalogous to working with black and white film or television

Color ImageHas perceptional attributes of hue, saturation, and lightnessDo we have to match every frequency in visible spectrum? No!

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Additive and Subtractive Color

Additive colorForm a color by adding amounts of three primaries

CRTs, projection systems, positive filmPrimaries are Red (R), Green (G), Blue (B)

Subtractive colorForm a color by filtering white light with cyan (C), Magenta (M), and Yellow (Y) filters

Light-material interactionsPrintingNegative film


The Human Eye


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Human Retina



Human Cones and Rods


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The Human Eye



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


Vector Graphics

Hearn & Baker 2004 Computer Graphics

VideoController

Monitor

System Bus

I/O Devices

CPUSystemMemory

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VideoController

Monitor

System Bus

I/O Devices

CPUFrameBuffer

SystemMemory




VideoController

Monitor

System Bus

I/O Devices

CPU

FrameBuffer

DisplayMemory

SystemMemory

DisplayProcessor

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Mapping Frame Buffer Display Surface

Hill 2001 Computer Graphics using OpenGL


Color Frame Buffers and the Monitor

Hill 2001 Computer Graphics using OpenGL

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Screen Depth


Indexed Colors


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Direct Colors


Display Depths

Indexed Color1-bit (2 colors) monochrome2-bits (4 colors) CGA4-bits (16 colors) EGA & higher resolution VGA8-bits (256 colors) lower resolution VGA & SVGA

Direct ColorHiColor

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)

Truecolor24-bits (8-bits per red/green/blue) 16.7 distinct colors

32-bit Color34-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


Keyboards

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

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Mice & Trackballs

Doug Englebart’s 1963 Mouse / Kingston Computer 2006 Mice & Trackball


Pens

Wacom Technology 2006 Cintiq 21UX & Intuos3 12x19 & TabletPC Hardware

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Gesture Systems

FingerWorks 2002 iGesture


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


Imaging Systems

Camera Specification

Image Formation

Pinhole Camera

Synthetic Camera Model

Ray Tracing

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Camera Specification

Six degrees of freedomPosition of center of lensOrientation

LensFilm sizeOrientation of film plane


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

CamerasMicroscopesTelescopesHuman visual system

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Elements of Image Formation

ObjectsViewerLight source(s)

Attributes that govern how light interacts with the materials in the sceneNote the independence of the objects, the viewer, and the light source(s)


Pinhole Camera

Angel 2006 Interactive Computer Graphics

xp= -x/z/d yp= -y/z/d

Use trigonometry to find projection of point at (x,y,z)

These are equations of simple perspective

zp= d

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Pinhole Camera Views



Synthetic Camera Model


center of projection

image plane

projector

p

projection of p

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Real vs. Synthetic Camera Models



Ray Tracing and Geometric Optics

One way to form an image is tofollow rays of light from apoint source finding whichrays enter the lens of thecamera. However, each ray of light may have multiple interactions with objectsbefore being absorbed or going to infinity.

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Geometric Pipeline


RasterizerVertices VertexProcessor

ClipperAssembler

PixelsFramgmentProcessor


Graphics Programming Library


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