Computer Graphics. Prof. Jaakko Lehtinen. with lots of material from Frédo Durand. Picture: Alexis Rufatt. T Spring 2013 Lehtinen Mar 22

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1 Computer Graphics Prof. Jaakko Lehtinen with lots of material from Frédo Durand Picture: Alexis Rufatt T Spring 2013 Lehtinen Mar 22

2 Luxo Jr. (Pixar, 1986) Pixar Animation Studios, 1986 Director: John Lasseter T Spring 2013 Lehtinen Mar 22 2

3 Plan for Today Really, it s a shameless pitch for T On the side, you ll get an idea of what computer graphics is Arf! T Spring 2013 Lehtinen Mar 22 3

4 Let s name some applications T Spring 2013 Lehtinen Mar 22 4

5 Movies / Visual Effects (VFX) T Spring 2013 Lehtinen Mar 22 5

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7 Video Games T Spring 2013 Lehtinen Mar 22 7

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9 Simulation T Spring 2013 Lehtinen Mar 22 9

10 CAD-CAM & Design, Advertising Hyltom Design Studio T Spring 2013 Lehtinen Mar 22 10

11 Architecture T Spring 2013 Lehtinen Mar 22 11

12 Global Illumination in Architecture The Light of Mies van der Rohe by Henrik Wann Jensen, model by Stephen Duck T Spring 2013 Lehtinen Mar 22 Henrik Wann 12 Jensen

13 T Spring 2013 Lehtinen Mar 22 Henrik Wann 13 Jensen

14 (Virtual Reality) T Spring 2013 Lehtinen Mar 22 14

15 Scientific Visualization T Spring 2013 Lehtinen Mar 22 15

16 Medical Imaging T Spring 2013 Lehtinen Mar 22 16

17 Differences between applications Games vs. movies? Architectural vs. medical visualization? T Spring 2013 Lehtinen Mar 22 17

18 Differences between applications Games vs. movies? Games need real-time performance (30 frames per second, FPS) Movie frames usually take hours to render each Architectural vs. medical visualization? Building visualization needs accurate simulation of illumination (want to know what it ll look like) Medical visualization aims to highlight important features in real-world datasets Etc. etc. etc. T Spring 2013 Lehtinen Mar 22 18

19 What you will learn in T Fundamentals of computer graphics algorithms Will give a pretty good idea of how to implement lots of the things just shown We ll concentrate on 3D, not 2D illustration or image processing Basics of real-time rendering and graphics hardware Basic OpenGL Not the focus, though: Means, not the end. You will get C++ programming experience Most things are written in it IRL T Spring 2013 Lehtinen Mar 22 19

20 What you will NOT learn OpenGL and DirectX hacks Most become obsolete every 18 months anyway! Software packages CAD-CAM, 3D Studio MAX, Maya Photoshop and other painting tools Artistic skills Game design T Spring 2013 Lehtinen Mar 22 20

21 How much Math? Lots of simple linear algebra Get it right, it will help you a lot! Some more advanced concepts Homogeneous coordinates Quaternions for interpolating rotations/orientations Ordinary differential equations (ODEs) and their numerical solution Sampling, antialiasing (some gentle Fourier analysis) Monte-Carlo integration Always in a concrete and visual context Deeper mathematic exposition in advanced class T Spring 2013 Lehtinen Mar 22 21

22 Prof Background (Navel gazing) T Spring 2013 Lehtinen Mar 22 22

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25 Prof Background (Navel gazing) I taught this class at MIT in 2009, now at Aalto T Spring 2013 Lehtinen Mar 22 25

26 Fireflies Questions? by Blobtrox Real Time, 4kb code+data (!!) 1st place in Assembly k intro compo code: MakeGho T Spring 2013 Lehtinen Mar music: Gwaur

27 What was Going on There? Monte Carlo solution of the integrodifferential equation that governs light transport in a participating medium ( volume rendering equation ) T Spring 2013 Lehtinen Mar 22 27

28 What was Going on There? Monte Carlo solution of the integrodifferential equation that governs light transport in a participating medium ( volume rendering equation ) Illustrates what I think is so damn cool about graphics you can use math and algorithms to draw pretty pictures! T Spring 2013 Lehtinen Mar 22 28

29 How do you make this picture? Remedy Entertainment / Microsoft Games Studios T Spring 2013 Lehtinen Mar 22 29

30 How do you make this picture? Modeling Geometry Materials Lights T Spring 2013 Lehtinen Mar 22 30

31 How do you make this picture? Modeling Geometry Materials Lights Animation Make it move T Spring 2013 Lehtinen Mar 22 31

32 How do you make this picture? Modeling Geometry Materials Lights Animation Make it move Rendering I.e., draw the picture! Lighting, shadows, textures... T Spring 2013 Lehtinen Mar 22 32

33 How do you make this picture? Modeling Geometry Materials Lights Animation Make it move Rendering I.e., draw the picture! Lighting, shadows, textures... Semester T Spring 2013 Lehtinen Mar 22 33

34 Modeling/Viewing Pipeline Meet the Stanford Bunny. He is one of the best-known characters in graphics. See ~turk/bunny/bunny.html for history. Stanford 3D Scanning Repository Hi! T Spring 2013 Lehtinen Mar 22 34

35 Modeling/Viewing Pipeline 1.Model the geometry Here a triangle mesh Also, specify materials T Spring 2013 Lehtinen Mar 22 35

36 Modeling/Viewing Pipeline 1.Model the geometry Here a triangle mesh Object coordinates Also, specify materials T Spring 2013 Lehtinen Mar 22 36

37 Modeling/Viewing Pipeline 1.Model the geometry 2.Place the objects in world space Each object has its own object space Only one world space Object Object coordinates World coordinates Another Object Space Coordinates World Origin T Spring 2013 Lehtinen Mar 22 37

38 Modeling/Viewing Pipeline 1.Model the geometry 2.Place the objects in world space 3.Pick viewing position and direction Camera position and orientation Object coordinates World coordinates View coordinates T Spring 2013 Lehtinen Mar 22 38

39 Modeling/Viewing Pipeline 1.Model the geometry 2.Place the objects in world space 3.Pick viewing position and direction 4.Transform objects to Object coordinates World coordinates View coordinates Image coordinates view space and project to image plane Compute shading and draw picture! T Spring 2013 Lehtinen Mar 22 39

40 Modeling/Viewing Summary Object coordinates World coordinates View coordinates Image coordinates T Spring 2013 Lehtinen Mar 22 Emil Praun

41 Modeling/Viewing Summary Some algorithms go the same sequence in the opposite direction (e.g. ray tracing) Object coordinates World coordinates View coordinates Image coordinates T Spring 2013 Lehtinen Mar 22 Emil Praun

42 Modeling/Viewing Summary Animation: Make these transformations vary with time Object coordinates World coordinates View coordinates Image coordinates T Spring 2013 Lehtinen Mar 22 Emil Praun

43 Another View Object coordinates World coordinates Modeling, animation View coordinates Image coordinates Viewing/rendering T Spring 2013 Lehtinen Mar 22 43

44 Questions? T Spring 2013 Lehtinen Mar 22 44

45 Coordinate Transformations Mostly linear algebra Homogeneous coordinates (remember your Kivelä!) Neat way of treating affine and perspective transforms as linear Perspective (for viewing) T Spring 2013 Lehtinen Mar 22 45

46 Modeling 2D curves, triangle meshes, smooth surfaces (Bézier, splines), subdivision surfaces T Spring 2013 Lehtinen Mar 22 46

47 Assignment 1: Curves & Surfaces Spline curves Surfaces of revolution Sweep surfaces T Spring 2013 Lehtinen Mar 22 47

48 Animation: Keyframing ACM 1987 Principles of traditional animation applied to 3D computer animation T Spring 2013 Lehtinen Mar 22 48

49 Character Animation: Skinning Animate simple skeleton Attach skin to skeleton Skin deforms smoothly with skeleton Used everywhere (games, movies) Epic Games Ilya Baran T Spring 2013 Lehtinen Mar 22 49

50 Pinocchio by Ilya Baran Automatic rigging, used in e.g. Blender T Spring 2013 Lehtinen Mar 22 50

51 Pinocchio This is an example of research done at universities This particular one, at MIT in Boston See Ilya s SIGGRAPH 2007 paper here T Spring 2013 Lehtinen Mar 22 51

52 Assignment 2: Hierarchical Modeling Animate character skeleton as tree of transformations Skinning : smooth surface deformation based on animated skeleton T Spring 2013 Lehtinen Mar 22 52

53 Particle systems (ODEs) Star Trek 2 T Spring 2013 Lehtinen Mar 22 53

54 T Spring 2013 Lehtinen Mar 22 Ron Fedkiw & 54colleagues

55 Physics (ODEs) Fire, smoke Cloth VLC Quotes because we do visual simulation T Spring 2013 Lehtinen Mar 22 55

56 Assignment 3: Physics Simulate cloth as a mass-spring network ODE numerics T Spring 2013 Lehtinen Mar 22 56

57 Eye Candy: Real-time fluid simulation T Spring 2013 Lehtinen Mar 22 57

58 Rendering: Ray Casting For every pixel construct a ray from the eye For every object in the scene Find intersection with the ray Keep if closest Visibility or hidden surface problem T Spring 2013 Lehtinen Mar 22 58

59 Rendering: Ray Tracing Shading: Interaction of light and material Secondary rays (shadows, reflection, refraction, indirect lighting) x T Spring 2013 Lehtinen Mar 22 59

60 Traditional Ray Tracing T Spring 2013 Lehtinen Mar 22 60

61 Ray Tracing + Soft Shadows T Spring 2013 Lehtinen Mar 22 61

62 Ray Tracing + Caustics T Spring 2013 Lehtinen Mar 22 62

63 Global (Indirect) Illumination T Spring 2013 Lehtinen Mar 22 63

64 Assignment 4: Ray Casting+Tracing Cast rays from the viewpoint Intersect with scene primitives Compute simple shading T Spring 2013 Lehtinen Mar 22 64

65 Textures and Shading T Spring 2013 Lehtinen Mar 22 65

66 Normal Map Example Paolo Cignoni Original Mesh 4M triangles T Fall 2012 Lehtinen 66

67 Normal Map Example Paolo Cignoni Simplified mesh, 500 triangles T Fall 2012 Lehtinen Simplified mesh + 67 normal mapping

68 Yes, All This Works T Spring 2013 Lehtinen Mar 22 68

69 Sampling & Antialiasing T Spring 2013 Lehtinen Mar 22 69

70 Shadows T Spring 2013 Lehtinen Mar 22 70

71 The Graphics Pipeline Ray Casting GPU For each pixel For each object Does object hit pixel? For each triangle For each pixel Does pixel hit triangle? T Spring 2013 Lehtinen Mar 22 71

72 The Graphics Pipeline Ray Casting GPU For each pixel For each object Send pixels to scene Both are ways of For each triangle For each projected pixel Project scene to pixels determining what is visible in each pixel just in different order. T Spring 2013 Lehtinen Mar 22 72

73 Phew! That s a lot of stuff! BUT: Mastering all this takes you a long way towards cool applications! Little Big Planet T Spring 2013 Lehtinen Mar 22 73

74 More Research Goodness My PhD student Miika Aittala is advancing the state of the art in realistic material appearance capture and rendering Highly competitive field Video T Spring 2013 Lehtinen Mar 22 74

75 Camera E LCD screen E t X(x) p p Material sample

76 Questions? T Spring 2013 Lehtinen Mar 22 76

77 T Prerequisites Not strictly enforced Calculus, Linear Algebra Solving equations, derivatives, integrals Vectors, matrices, basis, solving systems of equations Optional review/introductory session All assignments are in C++ Optional review/introductory session T Spring 2013 Lehtinen Mar 22 77

78 Grading Policy Assignments: 70% Two-week programming assignments Must be completed individually No final project Midterm Quiz+Final Exam: 25% Participation: 5% Can make a difference to your grade! T Spring 2013 Lehtinen Mar 22 78

79 Assignments: Scoring Fulfill all requirements: you get a 10 Partial success judged case by case All assignments include starter code and detailed instructions, maybe going into more detail than lectures Each assignment includes a number of extra credit tasks ranging from easy to possibly very hard Open-ended scale T Spring 2013 Lehtinen Mar 22 79

80 Extra Credit: Why Bother? 1st: it s fun! 2nd: prizes! Fall 2012: Three students with highest total assignment scores got a private tour at Remedy Entertainment, makers of Max Payne, Alan Wake, Death Rally Face-to-face with the people who do the games and the tech Advanced class (5310), this spring: Final rendering competition prize a very fast GPU donated by NVIDIA And... T Spring 2013 Lehtinen Mar 22 80

81 Juror Luca Fascione Rendering Research Lead Weta Digital

82 What Makes Graphics Fun? You can look at it from several angles Anything that looks good will do in many applications... Means you can really be creative once you know the basics....but doing stuff right can be really involved. Feels pretty nice when all that math and CS gives you a pretty picture or animation! There is a continuum in between visualparadox.com T Spring 2013 Lehtinen Mar 22 82

83 That s All Folks! Looking forward to seeing you in the fall! visualparadox.com T Spring 2013 Lehtinen Mar 22 83