Post on 12-Jan-2016
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CSC 461: Lecture 1CSC 461: Lecture 1 11
Lecture 1: IntroductionLecture 1: Introduction
ObjectivesObjectives
Explore what computer graphics is aboutExplore what computer graphics is about
Survey some application areasSurvey some application areas
Introduce a history of computer graphicsIntroduce a history of computer graphics
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Computer GraphicsComputer GraphicsDeals with all aspects of Deals with all aspects of creating images with a creating images with a computer computer – HardwareHardware– Software Software – ApplicationsApplications
ExampleExample– Where did this image Where did this image
come from?come from?– What hardware/software What hardware/software
did we need to produce did we need to produce it?it?
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Preliminary AnswerPreliminary Answer
ApplicationApplication: The object is an artist’s : The object is an artist’s rendition of the sun for an animation to be rendition of the sun for an animation to be shown in a domed environment shown in a domed environment (planetarium)(planetarium)
SoftwareSoftware: Maya for modeling and rendering : Maya for modeling and rendering but Maya is built on top of OpenGLbut Maya is built on top of OpenGL
HardwareHardware: PC with graphics cards for : PC with graphics cards for modeling and renderingmodeling and rendering
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Basic Graphics SystemBasic Graphics System
Input devices Output device
Image formed in FB
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Frame bufferFrame bufferA portion of memory storing pixels – to be A portion of memory storing pixels – to be mapped to the displaymapped to the displayPixels – picture elements encompassing a picture Pixels – picture elements encompassing a picture Picture – produced as array -- the raster – of Picture – produced as array -- the raster – of pixelspixelsVideo/Dynamic Random-Access Memory Video/Dynamic Random-Access Memory (V/DRAM) – fast redisplay of contents of frame (V/DRAM) – fast redisplay of contents of frame bufferbufferDepth of frame buffer – number of bits used for Depth of frame buffer – number of bits used for each pixel, such as color, lighting, shading, each pixel, such as color, lighting, shading, material, etc.material, etc.Resolution – number of pixels in the frame bufferResolution – number of pixels in the frame bufferColors – true color (RGB-color), indexed color Colors – true color (RGB-color), indexed color (discrete color)(discrete color)
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Cathode-Ray Tube (CRT) – most PCsCathode-Ray Tube (CRT) – most PCsCalligraphic CRT – line-drawing device, random Calligraphic CRT – line-drawing device, random scan, electron beam emits from any position to any scan, electron beam emits from any position to any positionpositionRaster mode CRT – display the contents of the Raster mode CRT – display the contents of the frame buffer at a rate high enough to avoid flickerframe buffer at a rate high enough to avoid flickerScreen refresh rate – typical CRTs emit light for Screen refresh rate – typical CRTs emit light for only a few milliseconds, redisplay the pictures in a only a few milliseconds, redisplay the pictures in a frequency frequency Two display methods Two display methods – Noninterlaced – pixels displayed row by row, the rate 50-Noninterlaced – pixels displayed row by row, the rate 50-
85 (Hz) times/second – used in computer systems85 (Hz) times/second – used in computer systems– Interlaced – odd rows and even rows refreshed Interlaced – odd rows and even rows refreshed
alternately, first draw at 60 Hz, the refresh rate 30 Hzalternately, first draw at 60 Hz, the refresh rate 30 Hz
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CRTCRT
Can be used either as a line-drawing Can be used either as a line-drawing device (calligraphic) or to display device (calligraphic) or to display contents of frame buffer (raster mode)contents of frame buffer (raster mode)
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Other Raster Mode Output DevicesOther Raster Mode Output Devices
Liquid-Crystal Display (LCD) – raster Liquid-Crystal Display (LCD) – raster mode, used in laptops, may or may not be mode, used in laptops, may or may not be refreshedrefreshed
Plasma panel – raster mode, used in TVsPlasma panel – raster mode, used in TVs
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Computer Graphics: 1950-1960Computer Graphics: 1950-1960
Computer graphics goes back to the Computer graphics goes back to the earliest days of computingearliest days of computing–Strip chartsStrip charts–Pen plottersPen plotters–Simple displays using A/D converters to go Simple displays using A/D converters to go
from computer to calligraphic CRTfrom computer to calligraphic CRT
Cost of refresh for CRT too high Cost of refresh for CRT too high –Computers slow, expensive, unreliableComputers slow, expensive, unreliable
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Computer Graphics: 1960-1970Computer Graphics: 1960-1970
Wireframe graphicsWireframe graphics
Project SketchpadProject Sketchpad
Display ProcessorsDisplay Processors
Storage tubeStorage tube
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Project SketchpadProject Sketchpad
Ivan Sutherland’s PhD thesis at MITIvan Sutherland’s PhD thesis at MIT–Recognized the potential of man-machine Recognized the potential of man-machine
interaction interaction –LoopLoop
Display somethingDisplay something
User moves light penUser moves light pen
Computer generates new displayComputer generates new display
–Sutherland also created many of the now Sutherland also created many of the now common algorithms for computer graphicscommon algorithms for computer graphics
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Display ProcessorDisplay ProcessorRather than have host computer try to refresh Rather than have host computer try to refresh display use a special purpose computer called a display use a special purpose computer called a display processor display processor (DPU)(DPU)
Graphics stored in display list (display file) on Graphics stored in display list (display file) on display processordisplay processor
Host Host compilescompiles display list and sends to DPU display list and sends to DPU
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Direct View Storage TubeDirect View Storage Tube
Created by TektronixCreated by Tektronix–Did not require constant refreshDid not require constant refresh–Standard interface to computersStandard interface to computers
Allowed for standard softwareAllowed for standard software
Plot3D in FortranPlot3D in Fortran
–Relatively inexpensiveRelatively inexpensiveOpened door to use of computer graphics for CAD Opened door to use of computer graphics for CAD communitycommunity
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Computer Graphics: 1970-1980Computer Graphics: 1970-1980
Raster GraphicsRaster Graphics
Beginning of graphics standardsBeginning of graphics standards–IFIPSIFIPS
GKS: European effortGKS: European effort– Becomes ISO 2D standardBecomes ISO 2D standard
Core: North American effortCore: North American effort– 3D but fails to become ISO standard3D but fails to become ISO standard
Workstations and PCsWorkstations and PCs
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Raster GraphicsRaster GraphicsImage produced as an array (the Image produced as an array (the rasterraster) of ) of picture elements (picture elements (pixelspixels) in the ) in the frame bufferframe buffer
Allow us to go from lines and wireframes to Allow us to go from lines and wireframes to filled polygonsfilled polygons
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PCs and WorkstationsPCs and Workstations
Although we no longer make the distinction Although we no longer make the distinction between workstations and PCs historically between workstations and PCs historically they evolved from different rootsthey evolved from different roots–Early workstations characterized byEarly workstations characterized by
Networked connection: client-serverNetworked connection: client-server
High-level of interactivityHigh-level of interactivity
–Early PCs included frame buffer as part of user Early PCs included frame buffer as part of user memorymemory
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Computer Graphics: 1980-1990Computer Graphics: 1980-1990
Realism comes to computer graphics Realism comes to computer graphics
smooth shading environmental mapping
bump mapping
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Computer Graphics: 1980-1990Computer Graphics: 1980-1990
Special purpose hardwareSpecial purpose hardware–Silicon Graphics geometry engineSilicon Graphics geometry engine
VLSI implementation of graphics pipelineVLSI implementation of graphics pipeline
Industry-based standardsIndustry-based standards–PHIGSPHIGS–RenderManRenderMan
Networked graphics: X Window SystemNetworked graphics: X Window System
Human-Computer Interface (HCI)Human-Computer Interface (HCI)
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Computer Graphics: 1990-2000Computer Graphics: 1990-2000
OpenGL APIOpenGL API
Completely computer-generated feature-Completely computer-generated feature-length movies (Toy Story) are successfullength movies (Toy Story) are successful
New hardware capabilitiesNew hardware capabilities–Texture mappingTexture mapping–BlendingBlending–Accumulation, stencil bufferAccumulation, stencil buffer
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Computer Graphics: 2000-Computer Graphics: 2000-
PhotorealismPhotorealism
Graphics cards for PCs dominate marketGraphics cards for PCs dominate market–Nvidia, ATI, 3DLabsNvidia, ATI, 3DLabs
Game boxes and game players determine Game boxes and game players determine direction of marketdirection of market
Computer graphics routine in movie Computer graphics routine in movie industry: Maya, Lightwaveindustry: Maya, Lightwave