CS488 - Introduction to Computer Graphics - Lecture 32


Modelling

Animation

Quite simple, really

`Specifiable': Think splines.

`Realistic': Think continuity.

  1. C0 continuity: no teleportation, possible discontinuities in velocity, which violate Newtonian mechanics.
  2. C1 continuity: no discontinuities in velocity, possible infinite accelarations.
  3. C2 continuity: acceleration continuous, possible infinite jerks.
  4. etc.

Most impotant point

Definition of `realistic' varies

  1. Between camera and actors
  2. As type of actor changes: compare classic Disney animation to live action, which obeys Newtonian dynamics (and other constraints, too)

Keyframe Animation

Above we described the goal of motion planning. How is it achieved in practice?

Usually by keyframe animation

Specification

  1. Degrees of freedom
  2. At t=t0
  3. Same at t=t1
  4. Interpolation algorithm

Editing the specification

  1. Change the values at the keyframes
  2. Change the interpolation algorithm
  3. Insert extra keyframes
  4. Delete keyframes

Comments

Without a direct manipulation interface keyframe animation is impossible,

Artists are good at doing keyframe animation

Physics

What's wrong with physics?

  1. Artistic problems
  2. Computation problems


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