Computer graphics power point slides lecture 02

Computer GraphicsComputer Graphics
Lecture 02Lecture 02
Graphics SystemsGraphics Systems

With the massive development in the field of computer
graphics a broad range of graphics hardware and software
systems are available.
With personal computers… usage of variety of interactive
input devices and graphics software packages
Higher-quality applications… usage of special-purpose
graphics hardware systems and technologies
Introduction to Graphics Systems

 VIDEO DISPLAY DEVICES
 RASTER-SCAN SYSTEMS
 RANDOM-SCAN SYSTEMS
 GRAPHICS MONITORS AND
WORKSTATIONS
 INPUT DEVICES
 HARD-COPY DEVICES
 GRAPHICS SOFTWARE
Graphics Systems

 Refresh Cathode-Ray Tubes
 Raster-Scan Displays
 Random-Scan Displays
 Color CRT Monitors
 Direct-View Storage Tubes
 Flat-Panel Displays
 Three-Dimensional Viewing Devices
Video Display Devices

Refresh Cathode-Ray Tubes
Refresh CRT
 Control Grid
 Focusing System
 Focusing in High Precision System
 Construction of Cathode-Ray
Tubes
 Persistence
 Resolution
 Aspect Ratio

Refresh Cathode-Ray Tubes Cont..

Refresh Cathode-Ray Tubes
Refresh CRT
 Control Grid
 Focusing System
 Focusing in High Precision System
 Construction of Cathode-Ray Tubes
 Persistence
 Resolution
 Aspect Ratio

Raster-Scan Displays
 Refresh Buffer or Frame Buffer
 Pixel
 Bitmap vs. Pixmap
 Horizontal Retrace & Vertical Retrace
 Interlaced vs. Non-interlaced Display

Random-Scan Displays
 Vector Display
 Refresh Display File
 Random-Scan vs. Raster-Scan

Color CRT Monitors
 Beam Penetration Method
 Shadow Mask Method

CRT Displays
Advantages
 Fast response (high
resolution possible)
 Full colour (large
modulation depth of E-
beam)
 Saturated and natural
colours
 Inexpensive, matured
technology
 Wide angle, high contrast
and brightness
Disadvantages
 Large and heavy (typ.
70x70 cm, 15 kg)
 High power consumption
(typ. 140W)
 Harmful DC and AC
electric and magnetic
fields
 Flickering at 50-80 Hz (no
memory effect)
 Geometrical errors at
edges

Direct View Storage Devices
 Primary Gun
 Flood Gun
 Advantages & Disadvantages

Flat-Panel Displays
 Properties
Volume, Weight, Power
 Emissive Display
Plasma Panels
 Non-Emissive Display
Liquid Crystal Display

Plasma-panel Displays
 Similar in principle to
fluorescent light tubes
 Small gas-filled capsules are
excited by electric field, emits
UV light
 UV excites phosphor
 Phosphor relaxes, emits some
other color

 Two glass plates separated
by neon gas
 Vertical and horizontal
conductors
 Very rugged
 No refreshing
 Screens can be transparent
and overlay documents
 Used to be available in
monochrome (Orange)
 Now available in colour

Advantages
–Large viewing angle
–Good for large-format displays
–Fairly bright
Disadvantages
–Expensive
–Large pixels (~1 mm versus ~0.2 mm)
–Phosphors gradually deplete
–Less bright than CRTs, using more power

Liquid Crystal Displays
 Liquid Crystal Display
 A transmissive technology
 Works by letting varying
amounts of a fixed-intensity
white backlight through an
active filter
 Organic crystals that align
themselves together
 When external force is
applied they realign
themselves
 This is used to change
polarisation and filter light

 Transmissive & reflective LCDs:
– LCDs act as light valves, not light emitters, and
thus rely on an external light source.
– Laptop screen: backlit, transmissive display
– Palm Pilot/Game Boy: reflective display

Advantages
 Small footprint (approx 1/6 of CRT)
 Light weight (typ. 1/5 of CRT)
 Low power consumption (typ. 1/4 of CRT)
 Completely flat screen - no geometrical errors
 Crisp pictures - digital and uniform colours
 No electromagnetic emission
 Fully digital signal processing possible
 Large screens (>20 inch) on desktops

Disadvantages
 High price (presently 3x CRT)
 Poor viewing angle (type. +/- 50 degrees)
 Low contrast and luminance (type. 1:100)
 Low luminance (Natural light) (type. 200 cd/m2)

Three-Dimensional Viewing Devices
Vibrating flexible mirror
Stereoscopic and virtual
-reality systems
-shutter glasses (with tracking)
-headset with tracking
-other VR devices
Holograms
NC-mills + soft material
Stereo-lithographic apparatus
(SLA)

Virtual reality = stimulation of the human senses to
simulate a fictive environment
eyes: private eye, head mounted displays (hmd)
ears: headphones, loudspeakers in hmd
tactile sense: data glove, data suit, treadmill
Virtual Reality Devices

•2 small screens display
•images for both eyes:
•high immersion degree
•head movement controls
•virtual camera
•artificial image only
•low resolution (e.g. 256 x 210)
•very expensive
•narrow view-angle
Head Mounted Display

ultrasound tracking device used with stereoscopic glasses to
track head position
Light Weight HMD

Computer graphics power point slides lecture 02

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