Lecture 1 Introduction Objectives Explore what computer graphics

Lecture 1: Introduction Objectives Explore what computer graphics is about Survey some application areas Introduce a history of computer graphics CSC 461: Lecture 1 1

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? CSC 461: Lecture 1 2

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 Open. GL Hardware: PC with graphics cards for modeling and rendering CSC 461: Lecture 1 3

Basic Graphics System Output device Input devices Image formed in FB CSC 461: Lecture 1 4

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) CSC 461: Lecture 1 5

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 CSC 461: Lecture 1 6

CRT Can be used either as a line-drawing device (calligraphic) or to display contents of frame buffer (raster mode) CSC 461: Lecture 1 7

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 CSC 461: Lecture 1 8

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 CSC 461: Lecture 1 9

Computer Graphics: 1960 -1970 Wireframe graphics Project Sketchpad Display Processors Storage tube CSC 461: Lecture 1 10

Project Sketchpad Ivan Sutherland’s Ph. D 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 CSC 461: Lecture 1 11

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 CSC 461: Lecture 1 12

Direct View Storage Tube Created by Tektronix –Did not require constant refresh –Standard interface to computers Allowed for standard software Plot 3 D in Fortran –Relatively inexpensive Opened door to use of computer graphics for CAD community CSC 461: Lecture 1 13

Computer Graphics: 1970 -1980 Raster Graphics Beginning of graphics standards –IFIPS GKS: European effort – Becomes ISO 2 D standard Core: North American effort – 3 D but fails to become ISO standard Workstations and PCs CSC 461: Lecture 1 14

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 CSC 461: Lecture 1 15

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 CSC 461: Lecture 1 16

Computer Graphics: 1980 -1990 Realism comes to computer graphics smooth shading CSC 461: Lecture 1 environmental mapping bump mapping 17

Computer Graphics: 1980 -1990 Special purpose hardware –Silicon Graphics geometry engine VLSI implementation of graphics pipeline Industry-based standards –PHIGS –Render. Man Networked graphics: X Window System Human-Computer Interface (HCI) CSC 461: Lecture 1 18

Computer Graphics: 1990 -2000 Open. GL API Completely computer-generated featurelength movies (Toy Story) are successful New hardware capabilities –Texture mapping –Blending –Accumulation, stencil buffer CSC 461: Lecture 1 19

Computer Graphics: 2000 Photorealism Graphics cards for PCs dominate market –Nvidia, ATI, 3 DLabs Game boxes and game players determine direction of market Computer graphics routine in movie industry: Maya, Lightwave CSC 461: Lecture 1 20