CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics1

Introduction to Advanced Animation• Types of animation• Low Level Control (a start) (Ch. 15)

• We’re going to be examining topics from chapters 15, 16, 17, 18 in the textbook.

• 15 – Low level control16 – Articulated structures17 – Soft object animation18 – Procedural animation

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics2

Plan

• Introduction (Ch. 15)• Skeletal animation (Ch. 17)• Curves and cubic interpolation (Ch. 15)• Kinematics and inverse kinematics (Ch. 16)• Procedural animation (Ch. 18)• Water and physical models

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics3

Types of Animation

• Procedural animation– Animation is defined by a computational result

• Representational animation– Animation is defined by example

• Stochastic animation– Animation is based on random phenomena

• Behavioral animation– Animation is a reaction

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics4

Low level control

• How do we specify animations?

• Assuming a simple skeleton with 12 3DOF joints– 36 numbers per frame– 64,800 numbers per minute– We just can’t do this manually– Would we ever have this?

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics5

Scripting systems

• We have some programming language that defines the motion– Procedural animation

(defop spin-cube-actor(param: color)(actor (local: (angle 0)

(d-angle (quo 3 runtime)) (my-cube (recolor color cube)))

(see (rotate angle y-axis my-cube))(define angle (plus angle d-angle))))

Actor Script Animation

System (ASAS)

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics6

Keyframing and “Tweening”

• Define motion at specific points• Interpolate between the points– Tweening – generating intermediate frames– Inbetweens – The generated intermediates

How to interpolate this example?

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics7

Types of interpolation

• Linear– x(t) = (1-t/t) x1 + t/t x2

• Cubic– x(t) = as3 + bs2 + cs + d– Where do we get a, b, c, d?

• Points, angles, orientations?

When does this not

look good?

CSE 872 Dr. Charles B. OwenAdvanced Computer Graphics8

Spline-driven animation

• We define a animation using control points that “attract” the animation

Control points may be on (interpolated control points) or near the curve

We’re going to cover curves shortly.