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Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Lecture 15 of 42 William H. Hsu.

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Presentation on theme: "Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Lecture 15 of 42 William H. Hsu."— Presentation transcript:

1 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Lecture 15 of 42 William H. Hsu Department of Computing and Information Sciences, KSU KSOL course pages: http://snipurl.com/1y5gchttp://snipurl.com/1y5gc Course web site: http://www.kddresearch.org/Courses/CIS636http://www.kddresearch.org/Courses/CIS636 Instructor home page: http://www.cis.ksu.edu/~bhsuhttp://www.cis.ksu.edu/~bhsu Readings: Disregard This Play aka Bingo: http://www.youtube.com/watch?v=SVtU5OS0c9Ahttp://www.youtube.com/watch?v=SVtU5OS0c9A SIGGRAPH 2007 highlights: http://www.youtube.com/watch?v=feBKaTJD-TAhttp://www.youtube.com/watch?v=feBKaTJD-TA Chapter 5, Eberly 2 e – see http://snurl.com/1ye72http://snurl.com/1ye72 Computer-Generated Animation (CGA) Overview

2 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Lecture Outline Animation Problems  Previsualization  Modeling  Keyframing  Dynamics and Interpolation  Lighting Fast Previsualization Modeling Keyframe Interpolation  Position  Orientation  Scale Camera Animation

3 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Let’s talk about computer animation Must generate 30 frames per second of animation (24 fps for film) Issues to consider:  Is the goal to replace or augment the artist?  What does the artist bring to the project?  Is the scene/plot fixed or responsive to user?  What can we automate? © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

4 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Computer Animation © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

5 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Keyframing Traditional animation technique Dependent on artist to generate ‘key’ frames Additional, ‘inbetween’ frames are drawn automatically by computer © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

6 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Keyframing From “The computer in the visual arts”, Spalter, 1999 How are we going to interpolate? © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

7 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Linear Interpolation Simple, but discontinuous velocity © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

8 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Nonlinear Interpolation Smooth ball trajectory and continuous velocity, but loss of timing © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

9 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Easing Adjust the timing of the inbetween frames. Can be automated by adjusting the stepsize of parameter, t. © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

10 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Style or Accuracy? Interpolating time captures accuracy of velocity Squash and stretch replaces motion blur stimuli and adds life-like intent © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

11 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Traditional Motivation Ease-in and ease-out is like squash and stretch Can we automate the inbetweens for these? “The Illusion of Life, Disney Animation” Thomas and Johnson © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

12 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics More squash and stretch © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

13 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Anticipation and Staging Don’t surprise the audience Direct their attention to what’s important © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

14 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Follow Through Audience likes to see resolution of action Discontinuities are unsettling © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

15 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Combined © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

16 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Secondary Motion Characters should exist in a real environment Extra movements should not detract © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

17 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Interpolation [1] Many parameters can be interpolated to generate animation Simple interpolation techniques can only generate simple inbetweens More complicated inbetweening will require a more complicated model of animated object and simulation © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

18 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Strengths  Animator has exacting control (Woody’s face) Weaknesses  Interpolation hooks must be simple and direct  Remember the problems with Euler angle interp?  Time consuming and skill intensive  Difficult to reuse and adjust © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics Interpolation [2]

19 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Cartoon Physics Homer3D Adapted from slides © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics Movies

20 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

21 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Examples Sports video games  Madden Football Many movie characters  Phantom Menace Cartoons © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

22 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Motion Capture Strengths Exactly captures the motions of the actor  Michael Jordan’s video game character will capture his style Easy to capture data © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

23 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Motion Capture Weaknesses Noise, noise, noise! Magnetic system inteference Visual system occlusions Mechanical system mass Tethered (wireless is available now) © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

24 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Motion Capture Weaknesses Aligning motion data with CG character  Limb lengths  Idealized perfect joints Reusing motion data  Difficult to scale in size (must also scale in time)  Changing one part of motion © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

25 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Motion Capture Weaknesses Blending segments  Motion clips are short (due to range and tethers)  Dynamic motion generation requires blending at run time  Difficult to manage smooth transition © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

26 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Movies Animating aliens – progress since late 1990s Retargeting motion – SIGGRAPH Highlight reels – SIGGRAPH 2007 and beyond Adapted from slides © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

27 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

28 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Examples Inanimate video game objects  GT Racer cars  Soapbox about why this is so cool Special effects  Explosions, water, secondary motion  Phantom Menace CG droids after they were cut in half © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

29 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Procedural Animation Very general term for a technique that puts more complex algorithms behind the scenes Technique attempts to consolidate artistic efforts in algorithms and heuristics Allows for optimization and physical simulation © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

30 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Procedural Animation Strengths Animation can be generated ‘on the fly’ Dynamic response to user Write-once, use-often Algorithms provide accuracy and exhaustive search that animators cannot © 2001 Brogan, D., University of Virginia CS 445 (Undergrad) / CS 645 (Graduate) – Introduction to Computer Graphics

31 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Summary Animation Problems  Previsualization  Modeling  Keyframing  Dynamics and Interpolation  Lighting Modeling Keyframe Interpolation  Position  Orientation  Scale

32 Computing & Information Sciences Kansas State University Lecture 15 of 42CIS 636/736: (Introduction to) Computer Graphics Terminology Tasks  Previsualization  Modeling  Keyframing  Lighting Keyframe Interpolation Dynamics  Forward – ballistic simulation  Inverse – ballistics (fire control) Kinematics  Forward – simulation of articulated model  Inverse – control of articulated model


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