Simulation
Simulation in animation is the use of physics solvers to compute complex motion (cloth, hair, fluids, smoke, rigid bodies) instead of keyframing each element by hand.
It adds a layer of realism and detail to 3D animation. Artists guide the simulation parameters to get the desired look while letting physics handle the heavy lifting.
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Sources
Academic papers, recognised industry standards, and canonical industry texts that back up claims in this entry.
- Physically Plausible Simulation for Character Animation. Levine, Popović, Eurographics/ACM SIGGRAPH Symposium on Computer Animation, 2011Supports: physics solvers for motion
- Physical Simulation for Animation and Visual Effects: Parallelization and Characterization for Handhelds. Sifakis et al., ACM SIGGRAPH Symposium on Interactive 3D Graphics, 2007Supports: physics solvers for animation
- Computer Animation: Algorithms and Techniques. Parent, Springer, 2012Supports: simulation realism in 3D
Frequently asked questions
Why simulate instead of keyframe?
Some motion is too complex to keyframe convincingly: cloth folding under a character's own movement, water splashing into a basin, hair reacting to wind. A simulation solver computes physically plausible motion automatically, faster than hand-keyframing and more accurate in detail. The trade-off is render time and the need to art-direct the result.
Are simulations slow to render?
Often, yes. Detailed fluid or smoke simulations can add hours to a single frame's render time. Most studios cache simulations to disk so they only run once, then re-use the cache across re-renders. The performance hit is planned for in production scheduling. Lighter simulations (cloth, hair) are typically fast enough to be standard on most projects.
How is AI changing simulation?
AI-trained solvers can produce simulation results that look close to high-quality physics solves, in a fraction of the compute time. They are starting to appear in mainstream tools for fluids, smoke, and cloth. Inside our AI-assisted animation workflow we use them for fast iteration in LookDev, with traditional solvers for final beauty passes.