1. Introduction to Computer Graphics CS 445 / 645 David Brogan dbrogan@cs.virginia.edu dbrogan@cs.virginia.edu

2. Administrivia Syllabus Instructor/TA coordinatesInstructor/TA coordinates PrereqsPrereqs TextsTexts AssignmentsAssignments Grading & Honor CodeGrading & Honor Code Topic listTopic listSyllabus Instructor/TA coordinatesInstructor/TA coordinates PrereqsPrereqs TextsTexts AssignmentsAssignments Grading & Honor CodeGrading & Honor Code Topic listTopic list

3. Impact of Computers Moore’s Law Power of a CPU doubles every 18 months / 2 years Moore’s Law Power of a CPU doubles every 18 months / 2 years

4. Impact of Video Games (Nvidia) Number of transistors on GPU doubles each 6 mos. Three times Moore’s LawThree times Moore’s Law –Good article on Jen-Hsun Huang, Nvidia CEO: http://www.wired.com/wired/archive/10.07/Nvidia_pr.html Number of transistors on GPU doubles each 6 mos. Three times Moore’s LawThree times Moore’s Law –Good article on Jen-Hsun Huang, Nvidia CEO: http://www.wired.com/wired/archive/10.07/Nvidia_pr.html $7 Billion Man $5.6 Billion Man Worldwide revenues Retro flashback??? Lee Majors Col. Steve Austin

5. Impact of Video Games But… Video game sales is roughly same as Hollywood boxofficeVideo game sales is roughly same as Hollywood boxoffice Americans bought $3.2 in VCRs and DVDs last yrAmericans bought $3.2 in VCRs and DVDs last yr Total revenues to movie studios is 5 times total video game revenuesTotal revenues to movie studios is 5 times total video game revenuesBut… Video game sales is roughly same as Hollywood boxofficeVideo game sales is roughly same as Hollywood boxoffice Americans bought $3.2 in VCRs and DVDs last yrAmericans bought $3.2 in VCRs and DVDs last yr Total revenues to movie studios is 5 times total video game revenuesTotal revenues to movie studios is 5 times total video game revenues

6. Future of Consoles 33 million PS2s33 million PS2s 3.9 million Xboxes3.9 million Xboxes –MSFT still losing $89 per console Predicted 200 million PDA/Cell game players in 2005Predicted 200 million PDA/Cell game players in 2005 –Do you believe it? 33 million PS2s33 million PS2s 3.9 million Xboxes3.9 million Xboxes –MSFT still losing $89 per console Predicted 200 million PDA/Cell game players in 2005Predicted 200 million PDA/Cell game players in 2005 –Do you believe it?

7. Graphics Applications Entertainment: Cinema Pixar: Monster’s Inc. Square: Final Fantasy

8. Graphics Applications Medical Visualization MIT: Image-Guided Surgery Project The Visible Human Project

9. Graphics Applications Everyday Use Microsoft’s Whistler OS will use graphics seriouslyMicrosoft’s Whistler OS will use graphics seriously Graphics visualizations and debuggersGraphics visualizations and debuggers Visualize complex software systemsVisualize complex software systems Everyday Use Microsoft’s Whistler OS will use graphics seriouslyMicrosoft’s Whistler OS will use graphics seriously Graphics visualizations and debuggersGraphics visualizations and debuggers Visualize complex software systemsVisualize complex software systems

10. Graphics Applications Scientific Visualization

11. Graphics Applications Computer Aided Design (CAD)

12. Graphics Applications Entertainment: Games GT Racer 3 Polyphony Digital: Gran Turismo 3, A Spec

13. The Basics Computer graphics: generating 2D images of a 3D world represented in a computer. Main tasks: modeling: (shape) creating and representing the geometry of objects in the 3D worldmodeling: (shape) creating and representing the geometry of objects in the 3D world rendering: (light, perspective) generating 2D images of the objectsrendering: (light, perspective) generating 2D images of the objects animation: (movement) describing how objects change in timeanimation: (movement) describing how objects change in time Computer graphics: generating 2D images of a 3D world represented in a computer. Main tasks: modeling: (shape) creating and representing the geometry of objects in the 3D worldmodeling: (shape) creating and representing the geometry of objects in the 3D world rendering: (light, perspective) generating 2D images of the objectsrendering: (light, perspective) generating 2D images of the objects animation: (movement) describing how objects change in timeanimation: (movement) describing how objects change in time

14. Why Study Computer Graphics? Graphics is cool I like to see what I’m doingI like to see what I’m doing I like to show people what I’m doingI like to show people what I’m doing Graphics is interesting Involves simulation, AI, algorithms, architecture…Involves simulation, AI, algorithms, architecture… I’ll never get an Oscar for my acting But maybe I’ll get one for my CG special effectsBut maybe I’ll get one for my CG special effects Graphics is fun Graphics is cool I like to see what I’m doingI like to see what I’m doing I like to show people what I’m doingI like to show people what I’m doing Graphics is interesting Involves simulation, AI, algorithms, architecture…Involves simulation, AI, algorithms, architecture… I’ll never get an Oscar for my acting But maybe I’ll get one for my CG special effectsBut maybe I’ll get one for my CG special effects Graphics is fun

15. Can we learn from history? Among the studies of natural causes and laws, it is light that most delights its students. Among all the great branches of mathematics, the certainty of its demonstrations pre-eminently elevates the minds of its investigators. Perspective, therefore, should be preferred above all man’s discourses and disciplines. In this subject the visual rays are elucidated by means and demonstrations which derive their glory nor only from mathematics but also from physics; the one is adorned equally with the flowers of the other. Leonardo da Vinci (1400’s) quoting John Pecham (1200’s)

16. Perspective

17. Machines

18. Leonardo Again There are some who look at the things produced by nature through glass, or other surfaces or transparent veils. They trace outlines on the surface of the transparent medium… But such an invention is to be condemned in those who do not know how to portray things without it, no how to reason about nature with their minds… They are always poor and mean in every invention and in the composition of narratives, which is the final aim of this science

19. Perspective Lorenzetti Birth of the VirginBirth of the Virgin 13421342Lorenzetti Birth of the VirginBirth of the Virgin 13421342

20. Leonardo The Last SupperThe Last Supper 14981498Leonardo The Last SupperThe Last Supper 14981498

21. Shape

22. We Labor On… Light Stage – 2002 USC, Institute for Creative Technologies Note: Paul Debevec will visit UVa in October to talk about this and other cool things

23. Display Technologies Cathode Ray Tubes (CRTs) Most common display device todayMost common display device today Evacuated glass bottleEvacuated glass bottle Extremely high voltageExtremely high voltage Heating element (filament)Heating element (filament) Electrons pulled towards anode focusing cylinderElectrons pulled towards anode focusing cylinder Vertical and horizontal deflection platesVertical and horizontal deflection plates Beam strikes phosphor coating on front of tubeBeam strikes phosphor coating on front of tube Cathode Ray Tubes (CRTs) Most common display device todayMost common display device today Evacuated glass bottleEvacuated glass bottle Extremely high voltageExtremely high voltage Heating element (filament)Heating element (filament) Electrons pulled towards anode focusing cylinderElectrons pulled towards anode focusing cylinder Vertical and horizontal deflection platesVertical and horizontal deflection plates Beam strikes phosphor coating on front of tubeBeam strikes phosphor coating on front of tube

24. Electron Gun Contains a filament that, when heated, emits a stream of electrons Electrons are focused with an electromagnet into a sharp beam and directed to a specific point of the face of the picture tube The front surface of the picture tube is coated with small phospher dots When the beam hits a phospher dot it glows with a brightness proportional to the strength of the beam and how often it is excited by the beam Contains a filament that, when heated, emits a stream of electrons Electrons are focused with an electromagnet into a sharp beam and directed to a specific point of the face of the picture tube The front surface of the picture tube is coated with small phospher dots When the beam hits a phospher dot it glows with a brightness proportional to the strength of the beam and how often it is excited by the beam

25. Display Technologies: CRTs Vector Displays Anybody remember Battlezone? Tempest?Anybody remember Battlezone? Tempest? Vector Displays Anybody remember Battlezone? Tempest?Anybody remember Battlezone? Tempest?

26. Display Technologies: CRTs Vector Displays Early computer displays: basically an oscilloscopeEarly computer displays: basically an oscilloscope Control X,Y with vertical/horizontal plate voltageControl X,Y with vertical/horizontal plate voltage Often used intensity as ZOften used intensity as Z Name two disadvantages Just does wireframe Just does wireframe Complex scenes  visible flicker Complex scenes  visible flicker Vector Displays Early computer displays: basically an oscilloscopeEarly computer displays: basically an oscilloscope Control X,Y with vertical/horizontal plate voltageControl X,Y with vertical/horizontal plate voltage Often used intensity as ZOften used intensity as Z Name two disadvantages Just does wireframe Just does wireframe Complex scenes  visible flicker Complex scenes  visible flicker

27. Display Technologies: CRTs Raster Displays Raster: A rectangular array of points or dotsRaster: A rectangular array of points or dots Pixel: One dot or picture element of the rasterPixel: One dot or picture element of the raster Scan line: A row of pixelsScan line: A row of pixels Raster Displays Raster: A rectangular array of points or dotsRaster: A rectangular array of points or dots Pixel: One dot or picture element of the rasterPixel: One dot or picture element of the raster Scan line: A row of pixelsScan line: A row of pixels

28. Display Technologies: CRTs Raster Displays Black and white television: an oscilloscope with a fixed scan pattern: left to right, top to bottomBlack and white television: an oscilloscope with a fixed scan pattern: left to right, top to bottom To paint the screen, computer needs to synchronize with the scanning pattern of rasterTo paint the screen, computer needs to synchronize with the scanning pattern of raster –Solution: special memory to buffer image with scan- out synchronous to the raster. We call this the framebuffer. Raster Displays Black and white television: an oscilloscope with a fixed scan pattern: left to right, top to bottomBlack and white television: an oscilloscope with a fixed scan pattern: left to right, top to bottom To paint the screen, computer needs to synchronize with the scanning pattern of rasterTo paint the screen, computer needs to synchronize with the scanning pattern of raster –Solution: special memory to buffer image with scan- out synchronous to the raster. We call this the framebuffer.

29. Display Technologies: CRTs Phosphers Flourescence: Light emitted while the phospher is being struck by electronsFlourescence: Light emitted while the phospher is being struck by electrons Phospherescence: Light emitted once the electron beam is removedPhospherescence: Light emitted once the electron beam is removed Persistence: The time from the removal of the excitation to the moment when phospherescence has decayed to 10% of the initial light outputPersistence: The time from the removal of the excitation to the moment when phospherescence has decayed to 10% of the initial light outputPhosphers Flourescence: Light emitted while the phospher is being struck by electronsFlourescence: Light emitted while the phospher is being struck by electrons Phospherescence: Light emitted once the electron beam is removedPhospherescence: Light emitted once the electron beam is removed Persistence: The time from the removal of the excitation to the moment when phospherescence has decayed to 10% of the initial light outputPersistence: The time from the removal of the excitation to the moment when phospherescence has decayed to 10% of the initial light output

30. Display Technologies: CRTs Raster Displays Frame must be “refreshed” to draw new imagesFrame must be “refreshed” to draw new images As new pixels are struck by electron beam, others are decayingAs new pixels are struck by electron beam, others are decaying Electron beam must hit all pixels frequently to eliminate flickerElectron beam must hit all pixels frequently to eliminate flicker Critical fusion frequencyCritical fusion frequency –Typically 60 times/sec –Varies with intensity, individuals, phospher persistence, lighting... Raster Displays Frame must be “refreshed” to draw new imagesFrame must be “refreshed” to draw new images As new pixels are struck by electron beam, others are decayingAs new pixels are struck by electron beam, others are decaying Electron beam must hit all pixels frequently to eliminate flickerElectron beam must hit all pixels frequently to eliminate flicker Critical fusion frequencyCritical fusion frequency –Typically 60 times/sec –Varies with intensity, individuals, phospher persistence, lighting...

31. Display Technologies: CRTs Raster Displays Interlaced ScanningInterlaced Scanning Assume can only scan 30 times / secondAssume can only scan 30 times / second To reduce flicker, divide frame into two “fields” of odd and even linesTo reduce flicker, divide frame into two “fields” of odd and even lines Raster Displays Interlaced ScanningInterlaced Scanning Assume can only scan 30 times / secondAssume can only scan 30 times / second To reduce flicker, divide frame into two “fields” of odd and even linesTo reduce flicker, divide frame into two “fields” of odd and even lines 1/30 Sec 1/60 Sec Field 1 Field 2 Frame

32. Display Technologies: CRTs Raster Displays Scanning (left to right, top to bottom)Scanning (left to right, top to bottom) –Vertical Sync Pulse: Signals the start of the next field –Vertical Retrace: Time needed to get from the bottom of the current field to the top of the next field –Horizontal Sync Pulse: Signals the start of the new scan line –Horizontal Retrace: The time needed to get from the end of the current scan line to the start of the next scan line Raster Displays Scanning (left to right, top to bottom)Scanning (left to right, top to bottom) –Vertical Sync Pulse: Signals the start of the next field –Vertical Retrace: Time needed to get from the bottom of the current field to the top of the next field –Horizontal Sync Pulse: Signals the start of the new scan line –Horizontal Retrace: The time needed to get from the end of the current scan line to the start of the next scan line

33. Display Technology: Color CRTs Color CRTs are much more complicated Requires manufacturing very precise geometryRequires manufacturing very precise geometry Uses a pattern of color phosphors on the screen:Uses a pattern of color phosphors on the screen: Why red, green, and blue phosphors?Why red, green, and blue phosphors? Color CRTs are much more complicated Requires manufacturing very precise geometryRequires manufacturing very precise geometry Uses a pattern of color phosphors on the screen:Uses a pattern of color phosphors on the screen: Why red, green, and blue phosphors?Why red, green, and blue phosphors? Delta electron gun arrangementIn-line electron gun arrangement

34. Display Technology: Color CRTs Color CRTs have Three electron gunsThree electron guns A metal shadow mask to differentiate the beamsA metal shadow mask to differentiate the beams Color CRTs have Three electron gunsThree electron guns A metal shadow mask to differentiate the beamsA metal shadow mask to differentiate the beams

35. Display Technology: Raster Raster CRT pros: Allows solids, not just wireframesAllows solids, not just wireframes Leverages low-cost CRT technology (i.e., TVs)Leverages low-cost CRT technology (i.e., TVs) Bright! Display emits lightBright! Display emits lightCons: Requires screen-size memory arrayRequires screen-size memory array Discreet sampling (pixels)Discreet sampling (pixels) Practical limit on size (call it 40 inches)Practical limit on size (call it 40 inches) BulkyBulky Finicky (convergence, warp, etc)Finicky (convergence, warp, etc) Raster CRT pros: Allows solids, not just wireframesAllows solids, not just wireframes Leverages low-cost CRT technology (i.e., TVs)Leverages low-cost CRT technology (i.e., TVs) Bright! Display emits lightBright! Display emits lightCons: Requires screen-size memory arrayRequires screen-size memory array Discreet sampling (pixels)Discreet sampling (pixels) Practical limit on size (call it 40 inches)Practical limit on size (call it 40 inches) BulkyBulky Finicky (convergence, warp, etc)Finicky (convergence, warp, etc)