Introduction to Computer Graphics Kurt Akeley CS248 Lecture 1 25 September

CS248 Lecture 1Kurt Akeley, Fall 2007 Instructor information Education and employment n BEE University of Delaware, n MSEE Stanford, n SGI co-founder, chief engineer, CTO, 1982–2000 n PhD (EE) Stanford, n NVIDIA graphics architect (part-time) n Microsoft Research Asia asst. director, n Principal Researcher, MSR Silicon Valley

CS248 Lecture 1Kurt Akeley, Fall 2007 Instructor information Professional experience n Graphics systems: GT, GTX, VGX, RealityEngine, … n OpenGL: specification, early extensions, ARB, … n SIGGRAPH: attend , papers chair 2000, … n SIGGRAPH Asia 2008: papers chair Teaching experience n Co-taught CS448, Real-time Graphics Architecture, with Pat Hanrahan fall 2001 and spring 2007 n Lectured in several SIGGRAPH courses n Have given lots of talks

CS248 Lecture 1Kurt Akeley, Fall 2007 Instructor information “Newark” laser printer controller (1979) GE4 without Clark Geometry Engine (1987)

CS248 Lecture 1Kurt Akeley, Fall 2007 Instructor information Fixed-viewpoint volumetric display (2004)

CS248 Lecture 1Kurt Akeley, Fall 2007 Instructor information This is my first n Stanford course on my own n time teaching an introductory graphics course n detailed exposure to some concepts I’m learning too! n Let’s interact n I’ll try not to cram too much into the lectures

CS248 Lecture 1Kurt Akeley, Fall 2007 Teaching assistants Andrew Adams Won game competition in ’04 TA’d course in ’05 and ’06 Justin Talbot Second-year PhD student BYU MS global illumination

CS248 Lecture 1Kurt Akeley, Fall 2007 Course content Based on the course as taught by Marc Levoy last year n More emphasis on OpenGL and applied graphics n Z-buffer, tuning, hardware, details & depth (why) Less emphasis on history and alternate approaches n Perspective in art, visibility algorithms, volume rendering Projects n First is new (still under construction) n Second is the same (for now) n Third (game competition) remains n But we may de-emphasize game play requirement n This course really isn’t about game play

CS248 Lecture 1Kurt Akeley, Fall 2007 Human perception Interactive graphics is (typically) for human viewers n Guided-missile design is a counterexample n Human will be presumed in this course Good designers know their customers’ needs and problems n Have basic understanding of visual perception n NTSC is a great engineering design example The evolution of computer graphics has been directed by the quirks of human perception, e.g., n Tri-color stimulus n Sensitivity to change in light reaching the eye

CS248 Lecture 1Kurt Akeley, Fall 2007 Purpose of computer graphics? Communication is the purpose Human perception is the context n Techniques leverage visual perception abilities Fidelity is a tool, not (necessarily) the goal n Virtual reality is great, but n Don’t want to be limited to reality n Want to do super reality n Non-photorealistic rendering (NPR) is valuable –Bill Buxton, Sketching User Experiences, 2006 n No apology is required for “approximations” n Especially for interactive graphics

CS248 Lecture 1Kurt Akeley, Fall 2007 Color perception Color is perceptual Stimulus is spectral energy in nm range Monochromatic differentiation requires: n Overlapping cone sensitivities (ratios) n Only two cone types Three cone types (a human quirk) n Enrich our perceptual experience n Require stimulation with (at least) three “colors” n RGB is the display tuple Normalized typical human cone cell responses to monochromatic spectral stimuli (Source: Wikipedia)

CS248 Lecture 1Kurt Akeley, Fall 2007 Pixels graphics pixel imaging CCD sensor (Bayer pattern) LCD display

CS248 Lecture 1Kurt Akeley, Fall 2007 Pixels Why do CCDs use the Bayer pattern? Why don’t LCD monitors use the Bayer pattern? What is graphics missing? n Microsoft ClearType n Claude Betrisey, Jim Blinn, Bodin Dresevic, Bill Hill, Greg Hitchcock, Bert Kely, Don Mitchell, John Platt, Turner Whitted, 20.4: Displaced Filtering for Patterned Displays, Society for Information Display, 2000.

CS248 Lecture 1Kurt Akeley, Fall 2007 Graphics image (pixels) lights (photons) viewer objects (triangles)

CS248 Lecture 1Kurt Akeley, Fall 2007 Physical reality (sort of) image (pixels) for (each photon) for (each triangle) for (each pixel) draw; lights (photons) objects (triangles)

CS248 Lecture 1Kurt Akeley, Fall 2007 Ray tracing image (pixels) for (each pixel) for (each triangle) for (each light) draw; objects (triangles) lights (photons)

CS248 Lecture 1Kurt Akeley, Fall 2007 Physical reality (sort of) lights image (pixels) for (each light) for (each triangle) for (each pixel) draw; objects (triangles)

CS248 Lecture 1Kurt Akeley, Fall 2007 Traditional graphics pipeline (OpenGL) lights image (pixels) for (each triangle) for (each light) for (each pixel) draw; objects (triangles)

CS248 Lecture 1Kurt Akeley, Fall 2007 Modern graphics pipeline (OpenGL 2.1) lights image (pixels) for (each triangle) for (each pixel) for (each light) draw; objects (triangles)

CS248 Lecture 1Kurt Akeley, Fall 2007 Global illumination Light paths are complex, not light  triangle  pixel Nature finds equilibrium efficiently Computers struggle 

CS248 Lecture 1Kurt Akeley, Fall 2007 Animation Sequence of still frames n Update rate: minimum of 24 hz or so n Flicker rate: minimum of 50 hz or so “Rule 1”: All discontinuous frame-to-frame changes correspond to discontinuous scene or visibility changes

CS248 Lecture 1Kurt Akeley, Fall 2007 Interactive graphics System latency Frame rate and flicker rate

CS248 Lecture 1Kurt Akeley, Fall 2007 API stacks GeForce 8800 OpenGL 2.1 VRML web application Radeon 9600 Direct3D 10 Unreal engine Gears of War GPU graphics API scene graph application

CS248 Lecture 1Kurt Akeley, Fall 2007 Direct3D 10OpenGL 2.1 Graphics APIs are architectures GeForce 8800 VRML web application Radeon 9600 Unreal engine Gears of War GPU graphics API scene graph application

CS248 Lecture 1Kurt Akeley, Fall 2007 Summary Communication is the purpose of computer graphics n Human perception is the context n Fidelity is a tool, not (necessarily) a goal Our focus will be interactive graphics n Instructor’s bias n Emphasis on OpenGL Your instructor is learning too n Your opinions, corrections, and concerns are appreciated!

CS248 Lecture 1Kurt Akeley, Fall 2007 Reading assignment Before Thursday’s class, read n Mark Segal and Kurt Akeley, The Design of the OpenGL Graphics Interface, unpublished n OpenGL Programming Guide n Chapter 1 - Introduction to OpenGL n Appendix D - Basics of GLUT: the OpenGL Utility Tool Also become familiar with n OpenGL, GLU, and GLUT Specifications n Extension specifications n … Optional: n David Blythe, The Direct3D 10 System, SIGGRAPH 2006 n Set up your OpenGL/GLUT programming environment

CS248 Lecture 1Kurt Akeley, Fall 2007 End