Animation and Physical Simulation
Animation and physical simulation generate motion over time for graphics, whether by artist control, physical laws, or procedural rules.
Definition
Computer animation is the generation of time-varying imagery by changing scene parameters over a sequence of frames, and physical simulation is the numerical solution of equations of motion to produce that change.
Scope
This area covers keyframe interpolation and skeletal animation of articulated characters, physically based simulation of rigid bodies, cloth, and fluids, the capture of real motion for use in animation, and procedural techniques that synthesize motion algorithmically.
Sub-topics
Core questions
- How is convincing motion authored and controlled?
- How are the equations of physical motion solved stably for graphics?
- How is real human and animal motion captured and reused?
- How can motion be generated automatically by rules or procedures?
Key concepts
- Keyframing and interpolation
- Skeletal animation and skinning
- Rigid-body dynamics
- Cloth and fluid simulation
- Motion capture
- Procedural motion
Key theories
- Keyframe interpolation
- Animators specify poses at key times and the in-between frames are interpolated, typically with splines, giving precise control over timing and motion while reducing the amount that must be hand-authored.
- Physically based modeling
- Motion can be generated by formulating Newtonian equations for bodies, springs, and continua and integrating them numerically, producing physically plausible behavior at the cost of stability and control challenges.
Clinical relevance
Animation and simulation drive film visual effects and animated features, video games, virtual training and surgical simulators, biomechanics and ergonomics analysis, and virtual-reality experiences.
History
Hand-drawn animation principles informed early keyframe systems; physically based simulation grew through the 1980s and 1990s with rigid-body, cloth, and fluid solvers, motion capture matured for film and games, and data-driven and learned motion synthesis is now active.
Key figures
- David Baraff
- Andrew Witkin
- Rick Parent
Related topics
Seminal works
- parent2012
- baraff2001
Frequently asked questions
- What is the difference between keyframe animation and simulation?
- In keyframe animation an artist specifies the motion directly and the computer fills in between poses, while in simulation the computer computes motion from physical laws, which is more automatic but harder to control precisely.
- Why is physical simulation difficult in graphics?
- Solving equations of motion numerically can become unstable, requires careful time stepping and collision handling, and must balance physical accuracy against the speed and artistic control that production demands.