Transcript Slide 1

Lecture 1: Introduction
Objectives
Explore what computer graphics is about
Survey some application areas
Introduce a history of computer graphics
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Computer Graphics
Deals with all aspects of
creating images with a
computer
– Hardware
– Software
– Applications
Example
– Where did this image
come from?
– What hardware/software
did we need to produce
it?
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Preliminary Answer
Application: The object is an artist’s
rendition of the sun for an animation to be
shown in a domed environment
(planetarium)
Software: Maya for modeling and rendering
but Maya is built on top of OpenGL
Hardware: PC with graphics cards for
modeling and rendering
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Basic Graphics System
Output device
Input devices
Image formed in FB
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Frame buffer
A portion of memory storing pixels – to be
mapped to the display
Pixels – picture elements encompassing a picture
Picture – produced as array -- the raster – of
pixels
Video/Dynamic Random-Access Memory
(V/DRAM) – fast redisplay of contents of frame
buffer
Depth of frame buffer – number of bits used for
each pixel, such as color, lighting, shading,
material, etc.
Resolution – number of pixels in the frame buffer
Colors – true color (RGB-color), indexed color
(discrete color)
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Cathode-Ray Tube (CRT) – most PCs
Calligraphic CRT – line-drawing device, random
scan, electron beam emits from any position to any
position
Raster mode CRT – display the contents of the
frame buffer at a rate high enough to avoid flicker
Screen refresh rate – typical CRTs emit light for
only a few milliseconds, redisplay the pictures in a
frequency
Two display methods
– Noninterlaced – pixels displayed row by row, the rate 5085 (Hz) times/second – used in computer systems
– Interlaced – odd rows and even rows refreshed
alternately, first draw at 60 Hz, the refresh rate 30 Hz
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CRT
Can be used either as a line-drawing
device (calligraphic) or to display
contents of frame buffer (raster mode)
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Other Raster Mode Output Devices
Liquid-Crystal Display (LCD) – raster
mode, used in laptops, may or may not be
refreshed
Plasma panel – raster mode, used in TVs
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Computer Graphics: 1950-1960
Computer graphics goes back to the
earliest days of computing
–Strip charts
–Pen plotters
–Simple displays using A/D converters to go
from computer to calligraphic CRT
Cost of refresh for CRT too high
–Computers slow, expensive, unreliable
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Computer Graphics: 1960-1970
Wireframe graphics
Project Sketchpad
Display Processors
Storage tube
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Project Sketchpad
Ivan Sutherland’s PhD thesis at MIT
–Recognized the potential of man-machine
interaction
–Loop
Display something
User moves light pen
Computer generates new display
–Sutherland also created many of the now
common algorithms for computer graphics
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Display Processor
Rather than have host computer try to refresh
display use a special purpose computer called a
display processor (DPU)
Graphics stored in display list (display file) on
display processor
Host compiles display list and sends to DPU
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Direct View Storage Tube
Created by Tektronix
–Did not require constant refresh
–Standard interface to computers
Allowed for standard software
Plot3D in Fortran
–Relatively inexpensive
Opened door to use of computer graphics for CAD
community
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Computer Graphics: 1970-1980
Raster Graphics
Beginning of graphics standards
–IFIPS
GKS: European effort
– Becomes ISO 2D standard
Core: North American effort
– 3D but fails to become ISO standard
Workstations and PCs
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Raster Graphics
Image produced as an array (the raster) of
picture elements (pixels) in the frame buffer
Allow us to go from lines and wireframes to
filled polygons
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PCs and Workstations
Although we no longer make the distinction
between workstations and PCs historically
they evolved from different roots
–Early workstations characterized by
Networked connection: client-server
High-level of interactivity
–Early PCs included frame buffer as part of user
memory
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Computer Graphics: 1980-1990
Realism comes to computer graphics
smooth shading
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environmental
mapping
bump mapping
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Computer Graphics: 1980-1990
Special purpose hardware
–Silicon Graphics geometry engine
VLSI implementation of graphics pipeline
Industry-based standards
–PHIGS
–RenderMan
Networked graphics: X Window System
Human-Computer Interface (HCI)
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Computer Graphics: 1990-2000
OpenGL API
Completely computer-generated featurelength movies (Toy Story) are successful
New hardware capabilities
–Texture mapping
–Blending
–Accumulation, stencil buffer
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Computer Graphics: 2000Photorealism
Graphics cards for PCs dominate market
–Nvidia, ATI, 3DLabs
Game boxes and game players determine
direction of market
Computer graphics routine in movie
industry: Maya, Lightwave
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