The Cartoon Animation Filter

Jue WangSteven Drucker

Maneesh AgrawalaMichael 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

x*(t) = x(t) + x’’(t) * -x’

time

x

x’’x’’

-x’’

-x’’ + x

-x’’ , x

Anticipation

Follow-through

An almost as boring animation

x*(t) = x(t) + x’’(t) * -x*(t) = x(t) + x (t) * - ’’

-LoG

Convolution with -LoG

Error in equation (2):

x*(t) = x(t) * -LoGx*(t) = x(t) + x(t) * -LoG

-LoG Parameters

• Amplitude – user set

• Width (frequency) – automatically set [later]

Image Sharpening

Image Sharpening

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

Squash and Stretch

x’’

LoGp(t) = LoG(t+t)

t ≈ x’’ · p

p

Squash and Stretch

time

x’’

• Volume Preservation– Inversely stretch/squash orthogonally to acceleration

Squash and Stretch

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

Livening Up Powerpoint

Livening Up Powerpoint

Enhancing Video Objects

Enhancing Video Objects

Enhancing Video Objects

• Need to maintain constraints– Simplest approach– Move figure in each frame vertically to keep

feet/skateboard in place

Enhancing Video Objects

Enhancing Video Objects

Enhancing Video Objects

Enhancing Video Objects

Enhancing Video Objects

Golfswing

• Apply filter to each DOF independently

• What should the filter width be?

Setting LoG Width*(t) = max|X()| *(t) = max|F(x’(t))| (t) = 2/ *(t)

time

original

fixed

adaptive

(over 32 frame window)

Walking

Boxers

Boxers

Boxers

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