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The Cartoon Animation Filter. Jue Wang Steven Drucker Maneesh Agrawala Michael Cohen. The Cartoon Animation Filter. Goal Add “liveliness” to any motion signal Should be Simple General As automated as possible Fast enough for real-time interaction. A very boring animation.
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The Cartoon Animation Filter Jue Wang Steven Drucker Maneesh Agrawala Michael Cohen
The Cartoon Animation Filter • Goal • Add “liveliness” to any motion signal • Should be • Simple • General • As automated as possible • Fast enough for real-time interaction
Follow-through x’’ -x’’ -x’’ , x -x’’ + x Anticipation x*(t) = x(t) + x’’(t)*- x x’ x’’ time
x*(t) = x(t) + x’’(t)*- x*(t) = x(t) + x(t)*- ’’ -LoG
Convolution with -LoG Error in equation (2): x*(t) = x(t) * -LoG x*(t) = x(t) + x(t) * -LoG
-LoG Parameters • Amplitude – user set • Width (frequency) – automatically set [later] s
Demo 3 • Show ball with vectors forward and backward • Show 3 copies of curve, original and time shifted forward and back • Convolve • Show squash and stretch ball again
p Squash and Stretch x’’ LoGp(t) = LoG(t+Dt) Dt ≈ x’’·p
Squash and Stretch x’’ • Volume Preservation • Inversely stretch/squash orthogonally to acceleration time
Related Work • Physically Based, lots • Stylized, e.g., Chenney et al. 2005, Igarashi et al. 2002 • Surface Deformation, lots… • Signal Based, e.g., • Unuma et al. 1995, • Bruderlin and Williams, 1995 • Video Paintbox, Collomosse 2004 • Motion Magnification, Liu et al. 2005
Enhancing Video Objects • Need to maintain constraints • Simplest approach • Move figure in each frame vertically to keep feet/skateboard in place
Golfswing • Apply filter to each DOF independently • What should the filter width be?
fixed s adaptive s Setting LoG Width s(t) = 2p /w*(t) w*(t) = maxw|X(w)| w w*(t) = maxw|F(x’(t))| (over 32 frame window) q original time
Discussion • (Almost) fully automated • NOT a tool for experts • But may make good first cut • Need better constraint maintenance • IK, physical constraints • Online (in-game) usage • Single animation adjusts to situation
Where from here? • Make a kid’s animation system