Computer Animation INF2050

Transcription

1 Computer Animation INF2050

2 Comments from Lasseter Keyframing Computers are stupid Worst case, keyframe required for every frame John discovered that some degrees of freedom (DOFs) require more keyframes than others to look natural You must start with a clear idea of the motion you desire Plan actions with thumbnail sketches and plot timing on exposure sheet Refer to sketches/timing frequently

3 Lasseter: 2-D vs. 3-D Native computer character is 3-D Sometimes makes it harder A character s hand may go through its body when seen from a certain angle Sometimes makes it easier Animation reuse: An animation may look very different when seen from different locations

4 Lasseter: Weight and Size Rendering can make realistic-looking objects (marble, feathers, steel) Good rendering benefits are lost if animation is poor Physics matters heavy things take longer to start/stop moving Proper timing/spacing of poses is more important than the poses themselves

5 Lasseter: Thinking Character Every motion must exist for a reason Mood Personality Attitude You must convey the character s thoughts to tell the story Use anticipation

6 Lasseter: Anticipation Lead with the eyes Move eyes first, with lock-in of focus a few frames before the head Head follows and leads the body by a few frames More delay implies more thought required Use this relationship as a tool External forces cause opposite timing relationship

7 Lasseter: Moving Holds Traditional 2-D animation permits holds Reuse of one drawing for multiple frames This is one way to control timing In computer animation action dies immediately Perhaps due to realistic rendering and smooth animations Eye picks it up every time

8 Lasseter: Moving Holds Have some part of the character continue to move in same direction during holds Remember to coordinate realism of character to realism of motions More realistic characters (rendering style and dimensions) require more realistic movements This rule limits the straightforward reuse of human facial mocap for non-human 3D characters

9 Lasseter: Emotion Character s personality conveyed through emotion Emotion dictates animation pace Distinguish emotional state of two characters through contrast in movement No two characters perform same action in same manner

10 Lasseter: Readability of Actions To make sure an idea or action is unmistakably clear, the audience s eye must be led to the right place at the right time Timing Not too slow or audience eyes wander Not too fast or action is misunderstood The faster the motion, the more critical it is to make the audience focus on it Harold Whitaker and John Halas, Timing for Animation, 1981

11 Lasseter: Readability of Actions To make sure an idea or action is unmistakably clear, the audience s eye must be led to the right place at the right time Staging Audience can only see one idea at a time Object of interest must be contrasted against rest of scene Pick strongest and simplest technique Ex: Still object vs. busy background

12 Lasseter: Readability of Actions To make sure an idea or action is unmistakably clear, the audience s eye must be led to the right place at the right time Anticipation First action should not be brought to complete stop before starting second Slight overlapping preserves flow Ex: Luxo Jr.

13 Lasseter: Story Tricks Animation must be timed to stay slightly ahead or behind audience s understanding Ahead conveys suspense and surprise Behind reveals the story to the audience before a character to convey character s discovery

14 Lasseter: Ask Why Why is this here? Does it further the story? Does it support the whole? Change of shape shows a character is thinking It is the thinking that gives the illusion of life. It is the life that gives meaning to the expression 1 It s not the eyes, but the glance not the lips, but the smile 2 1. Frank Thomas and Ollie Johnston, Disney Animation The Illusion of Life, Saint-Exupery, Wind, Sand, and Stars, Alma 1932 Leora Culén

15 Johnston Notes Use attitudes and actions to illustrate ideas and thoughts, not words and mechanical movements Squash and stretch the entire body for attitudes Preserve volume Useful for face too

16 Johnston Notes Change of expression and dialog are points of interest don t move head too much Concentrate on drawing clear, not clean Everything has a function know why Let the body attitude echo the facial Find best part of character s pose to squash and stretch

17 Johnston Notes The eye is pulled by the eyebrow muscles Get a plastic quality in the face Cheeks, mouth, and eyes The audience has a difficult time reading the first 6 8 frames Actions can be eliminated and staging cheated if it simplifies the picture you are trying to show and it doesn t disturb the audience

18 Johnston Notes Spend half your time planning your scene and the other half animating How to animate a four-legged walk: Work out acting patterns with squash and stretch in body, neck, and head Animate the legs Adjust up and down motion of body according to legs

19 Anticipation Can be anatomical Swinging your foot back before kicking Device that attracts viewer s attention Staring off camera until character enters at that position Can help convey mass. More wind-up or concentration implies increased scale

20 Staging Contrast is powerful staging technique Motion is one example Original Disney characters were black and white (no grayscale) Important motions had to be drawn in silhouette because limbs passing in front of others were not easy to see Even when grayscale (and color) is possible, silhouette makes actions more visible

21 Follow through and Overlapping Action "It is not necessary for an animator to take a character to one point, complete that action completely, and then turn to the following action as if he had never given it a thought until after completing the first action. When a character knows what he is going to do he doesn't have to stop before each individual action and think to do it. He has it planned in advance in his mind." Walt Disney

22 Production Line Film Sequences Shot/Scene Frames Preliminary story Script Storyboard Model Sheet Multiple drawings for each character Exposure Sheet Sound track cues, camera moves, and compositing info for each frame Route Sheet Personnel responsible for each scene

23 Who Does What Story Department: build the storyboard Art Department: build consistent look to coloring, lighting, models Modeling Department: build character and prop models. Give character s hooks that animators can use to move Layout Department: build 3-D world for staging and blocking

24 Who Does What Shading Department: builds texture maps, shaders, lighting models Animation Department: animate Lighting Department: position lights (hundreds) and camera to create final image Camera Department: I want to be a cowboy render wrangling

25 Editing Nonlinear editing Cut and paste frames anywhere in animation Film splicing Video tape copying Source Destination (Assemble Editing) Character generator and special effects Cannot splice into middle of destination reel (linear editing) Industry standard: Sony BetaSP Frame accurate inserts Low quality degredation

26 Digital Editing Frames are always represented digitally (no degeneration) Infinite compositing 21Mb/sec required for playback 1 hour of video = 76 Gb of storage D1 and digital Betacam are industry standard

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