CSE 872 CSE 872. Basic information Class web page. Advanced Computer Graphics. Class: T Th 12:40pm -2:00pm Office hour:

Transcription

1 CSE 872 Advanced Computer Graphics 1 CSE 872 Basic information Class web page Class: T Th 12:40pm -2:00pm Office hour: T 2:00-3:00pm by appointment 2

2 CSE 872 Instructor: Yiying Tong (Ian) Office: 1140 EB Office #: Computer Graphics Entered new age Fluid & surface tension subdivision surfaces Pixar/Disney Rigid body simulation Motion blur vector field design 3D texturing Depth of field 4

3 [20 th Century Fox] 5 Not Just fantasy Movies [Zhou et al 10] 6

4 More seriously CAGD Scientific Visualization Information Visualization Medical Imaging Simulation & Training Virtual Reality Image/Video Processing 7 Resources Conferences (incomplete list) General: ACM SIGGRAPH, EUROGRAPHICS, Pacific Graphics, i3d Animation: SCA, CASA Modeling: SGP, SoCG, SMI, SPM, SMA Rendering: EGSR, NPAR Others: GDC, IEEE-VR, CGIM, VIS, InfoVis Journals (incomplete list) ACM ToG, IEEE TVCG, CGF, VC, C&G, etc 8

5 The Graphics Process 3D Geometric Models 3D Animation Definition Lighting Information Rendering Texture Information Image Storage and Display 9 Geometric Modeling How do we Represent 3D objects Construct 3D objects Manipulate 3D objects 10

6 Geometric Modeling How do we Represent 3D objects Construct 3D objects Manipulate 3D objects 11 Represent 3D Objects Triangular Mesh 12

7 Represent 3D Objects Triangular Mesh 13 Represent 3D Objects Subdivision Surface coarse mesh & subdivision rule 14

8 Represent 3D Objects Subdivision Surface 15 Represent 3D Objects Parametric Surface x=f(u,v), y=g(u,v), z=h(u,v) 16

9 Represent 3D Objects Implicit Surface f (x, y, z) = 0 17 Geometric Modeling How do we Represent 3D objects Construct 3D objects Manipulate 3D objects 18

10 Construct 3D Objects 3D Scanning Metris Cyberware 19 Construct 3D Objects 3D Scanning [Digital Michelangelo Project] 20

11 Construct 3D Objects Interactive Modeling the world in basic shapes 21 Construct 3D Objects Interactive Modeling the world in basic shapes 22

12 e.g.suggestive Sketch [Tsang 04 (image below), Igarashi01] 23 Construct 3D Objects Interactive Modeling Maya, 3DS Max, ZBrush 24

13 Construct 3D Objects Displacement Map 25 Construct 3D Objects Displacement Map 26

14 Geometric Modeling How do we Represent 3D objects Construct 3D objects Manipulate 3D objects 27 Manipulate 3D Objects 3D Mesh Deformation 28

15 GPU implementation 29 Texturing What s texture? 30

16 Texturing What s texture? 31 Texturing What s texture? 32

17 Texturing Make 3D objects realistic without texture with texture 33 Texturing Texture Painting Laborious, require artistic skills [Igarashi and Cosgrove 2001] [Lévy 2003] 34

18 Texturing Texture Synthesis Automatic, only repeated patterns [Praun et al. 2000] [Zhang et al. 2003] 35 Texturing Texture Mapping Interactive, easy to use Stanford Bunny 6 photographs of another bunny 36

19 Texturing Texture Montage 37 Texture Mapping Triangle Mesh Vertex 1 x 1 y 1 z 1 Vertex 2 x 2 y 2 z 2 Face Face

20 Texture Mapping Triangle Mesh Vertex 1 x 1 y 1 z 1 Vertex 2 x 2 y 2 z 2 s 1 t 1 s 2 t 2 Face Face t s 39 Texture Mapping Triangle Mesh Vertex 1 x 1 y 1 z 1 Vertex 2 x 2 y 2 z 2 s 1 t 1 s 2 t 2 Face Face t s 40

21 Rendering 3D Geometric Models 3D Animation Definition Turning everything into pictures Transformation, Clipping, Perspective Rendering Image Generation Image Storage & Display Texture Information 41 Rendering Interaction of Light and Matter eye light 42

22 Rendering Equation r r r r r r r r B( ωo ) = L( ωi ) V ( ωi ) ρ( ωi, ωo ) max(0, n ωi ) dωi ω r i n r r ωo eye light 43 Rendering: BRDFs 44

23 Rendering: Shadows without shadow with shadow 45 Rendering: Interreflections without inter-reflection with inter-reflection 46

24 Rendering: Caustics without caustics with caustics 47 Rendering: Translucent BRDF BSSRDF 48

25 Real-time Rendering Lighting full env. map single area light [Blinn76] Precomputed Radiance Transfer [Moeller02] [Crow77] [Ashikhmin02] [Sloan02] [Ng03] [Zhou05] [Ren06] [Sun07] point lights simple shadows [Heidrich00] inter- reflections Transport Complexity 49 Character Animation Mostly commonly modeled by rigging Motion specified by Keyframing (often w/ IK) Mocap (retargeted) 50

26 Simulation Physics-based (inspired) Finite Element Method Variational Principle Various Speed-up techniques (hacks) Precomputation Low-res sim. combined w/ captured details Model reduction 51 Course Structure General concepts Modeling Rendering Animation/Simulation basic math tools (nothing scary) Selected recent research topics: mesh processing physically-based simulation non-photorealistic rendering 52

27 More on 2 nd Half Recent work interesting selected topics you ll need to read papers generally not textbook material real way to learn: implement subjects: flexible 53 Assignments Assignments (60% of the grade) Simple Physically-based Anim Build your own OpenGL (C/C++) Geometry Processing Team Project (30%) Implement one Better, a novel idea 54

28 CSE 872 Assignments programming language agnostic however we can only help so much no midterm, no final you don t need 100% to pass! 55 1 Modeling Triangular Mesh Basics parameterization Scene-graph Object representations B-rep, CSG Spatial organizations Octree, kd-tree, BSP 56

29 2 Rendering Scan converter Ray-tracing Stochastic ray-tracing Photon mapping Precomputed radiance transfer 57 3 Animation Scripting Keyframing Kinematics Motion Processing Higher Level Animation Dynamics and Simulation 58

30 4 Image-based Methods Image-based rendering Lightfield/lumigraph Non-photorealistic rendering Illustration Arstistic style 59 5 Basic transformations Revisit the basics Translation Rotation Scaling Homogeneous Coordinates Quaternions 60

31 Renderer Impl Basic Physics For animation and simulation: Rigid body dynamics Deformable objects Fluids 62

32 7 Linear Algebra Linear equations Conjugate gradient Cholesky Decomp. Eigenvalue problem Special equations FFT for 2D Poisson equation 63 8 Texture Synthesis Given a texture, create more All examples from Wei & Levoy 64

33 8 Surfaces/Meshes We ll stick to triangles 65 9 Curvature, Invariants w/o Derivatives Why do we care? theory: special surfaces minimal, CMC, integrable, etc. computation: simulation/processing Grape (u. of Bonn) Grinspun et al. Grinspun et al. Desbrun 66

34 10 Parameterizations What is a parameterization? function from some region Ω R 2 to the embedded surface M R 3 Image from Sander et al Simulation w/ Meshes Example: Cloth time evolution of a mesh subject to internal forces stretch and bending external forces gravity, drag, user applied forces setting it up From Volino & Magnenat-Thalmann 68

35 12 Thin shells and plates Thin, flexible objects Shells are naturally curved Plates are naturally flat Shadows Accentuate 3D effects 70

36 14 Field Visualization Stalling et al. Cabral et al. Stalling et al Volume of Data How to see it? 72

37 16 Implicit Surfaces Subsurface Scattering Lighting effect semi-translucent materials skin, leaves, marble, milk, etc. 74

38 18 Mesh Simplification Simplification highly detailed meshes from scanning iso-surface extraction get fewer triangles with good approximation Subdivision Surface Smooth surfaces as the limit of a sequence of refinements 76

39 20 Fluid Simulation Spline Surfaces e.g. tensor product basis Q( u, v) = k k i= 0 j= 0 p b ( u) b ij i j ( v) Image courtesy of Watt & Watt, Advanced Animation and Rendering Techniques 78

40 Your comments? If you can t decide now, Send them to ytong@msu.edu. Thanks! 79 Acknowledgement In alphabetic order: Mathieu Desbrun, Mark Meyer, Ulrich Neumann, Charles Owen, Peter Schröder, Kun Zhou 80