Character Animation and Simulation

01Purpose and scope

• This manual supports the course Character Animation and Simulation. It describes how the work is actually done in a small studio or production team, from the first shot breakdown through the final handoff of a character performance with secondary motion such as cloth, hair, props, and soft bodies.
• The scope covers keyframe and procedural animation of rigged characters, the setup of simulation passes that run on top of that animation, and the review and file handling needed to get a shot approved. It does not teach modeling, texturing, lighting, or rendering in depth, although those stages depend on animation decisions and are referenced where they matter.
• Readers include animators who need a reference for pass order and review habits, technical artists who set up rigs and simulation caches, and supervisors who decide what counts as ready. Practices differ between feature film, episodic television, games, and commercial work, and the notes here point out where those differences change the job.

02Core principles

• Performance comes first. A character's pose, timing, and weight carry the story, and simulation only adds to that. If a cloth pass fights the acting, the cloth pass is wrong, even if the physics is correct.
• Keep the animation editable. Animators should be able to change a key, retime a beat, or swap a pose after the simulation has been baked without rebuilding the whole shot. This means keeping rig controls clean, avoiding baked corrections on top of baked corrections, and naming things consistently.
• Use the simplest method that meets the shot. A hand-keyed secondary motion is often faster and more controllable than a full solver run for a small prop. Simulation earns its place when the motion is too complex, too repetitive, or too physically dependent to key by hand.

03Planning and preparation

• Start with a shot breakdown. Read the storyboard, animatic, and dialogue track, then write down the key poses, the beats that must land, the camera angles that will be used, and every point where a secondary element reacts to the body. A breakdown that takes an hour usually saves a day of rework.
• Confirm the rig and the asset versions before any keys are set. Check that the rig supports the required controls, that the character model matches the approved version, and that the frame rate and scene units match the production standard. Mismatched units and frame rates are common causes of cloth and hair solvers behaving strangely.
• Decide which simulations will run and in what order. A typical order is body animation, collision proxy setup, cloth or hair simulation, a cache or bake, then a final animation polish that does not disturb the cache. Write this order down so the animator, the simulation artist, and the lighter all expect the same file state at each step.

04Recommended workflow

1. 1
   : Block the shot with rough poses on the key frames only. Work at a playable speed and check the silhouette from the camera, not just from the default perspective view. Rough blocking is cheap to change, so make the big decisions here.
2. 2
   : Refine the timing with spacing charts or a dope sheet. Move the breakdowns and in-betweens until the action reads at full speed. Check holds, overlaps, and anticipation on the main joints before adding detail to the hands and face.
3. 3
   : Add the performance layer. Work on the face, eyes, and hands once the body reads correctly. Keep eye lines and head turns aligned with what the character is looking at, and check the mouth shapes against the dialogue track at the frame rate used for the final shot.
4. 4
   : Set up collision proxies for any simulated element. Use simplified geometry for the body, such as capsules or low-resolution meshes, and make sure the proxy follows the animated pose. Test the proxy by playing the shot with the proxy visible and looking for interpenetration at the elbows, knees, and shoulders.
5. 5
   : Run the simulation on a fixed frame range with the animation locked. Start with a low-resolution preview to find obvious failures such as flipping, popping, or tangling. Then run the production resolution and write the results to a cache that can be reloaded without recalculating.
6. 6
   : Review the cached simulation against the animation. Scrub the shot at full speed and look for moments where the secondary motion lags, overshoots, or hides the primary action. Correct the simulation settings first, and only add manual keys to the cloth or hair if the solver cannot reach the look without them.
7. 7
   : Finalize and export. Bake the approved animation and cache into the shot file, remove temporary helper objects, and export the shot in the agreed interchange format such as FBX or USD. Confirm that the exported file opens cleanly in the next department's software before marking the shot ready.

05Quality checks, risk controls and compliance

• Run a standard set of checks before any shot leaves the animation stage. Look for foot sliding during planted contact, unintended scale or rotation changes on the root, jitter in the spine and shoulders, and unexplained keys on channels that should be static. Check the cache for popping, interpenetration with the body proxy, and clipping through the floor or props. Many teams keep a short written list of these checks and tick it off on every shot.
• Control risk by keeping versions and caches separate from the working scene. A simulation that is rerun on a changed animation can silently replace an approved cache, so name caches by version and store the animation version they were built from. Keep a record of which frame range was simulated, because a cache that is shifted by a few frames will look wrong in the edit.
• Compliance questions are mostly about rights and content. Motion capture data, reference footage, and licensed character rigs often carry usage terms that limit where they can be used, how long they can be kept, and whether they can be shared with vendors. Requirements for performance capture of real people, including consent and data handling, depend on jurisdiction and on the contracts involved. Check the current terms with the production legal contact or the authoritative source for your location. This guidance does not replace legal review, approved studio procedures, or the authorization required for a given asset.

06Collaboration and documentation

• Animators, simulation artists, lighters, and supervisors all touch the same shot, so the shot file needs clear ownership. Agree on which department can change the rig, which can change the simulation settings, and which can edit keys after the cache is built. When a department needs a change outside its area, it should send a note with the shot name, the version, and the frame range, not a verbal request that gets lost.
• Keep a short shot log. Record the version of the animation and rig used, the solver settings, the cache location, the frame range, and any known issues that were accepted. A new person picking up the shot should be able to rerun the simulation from this log without asking the original artist.
• Review sessions work best when the reviewer has the reference in the same frame as the shot. Use playblasts or viewer exports at the final camera and frame rate, and make comments on specific frames with a single clear action. Avoid notes such as make it better, and prefer notes such as hold the head turn two frames longer so the line lands.

07Measures and continuous improvement

• Track a few indicators that reflect the real cost and quality of the work. Useful measures include the number of review rounds per shot, the number of simulation reruns after approval, the time spent on cleanup between cache and final export, and the count of checks that failed on first review. These numbers show where the pipeline is losing time, and they are more useful when compared within one project than across unrelated projects.
• Hold a short retrospective at the end of each sequence. Ask which simulation settings were reused successfully, which rig controls caused the most confusion, and which checks caught real problems. Turn the answers into updated presets, a clearer checklist, or a small change to the rig, and note the change in the shared documentation.
• The practices in this manual are a starting point. Feature work often allows more time for hand-keyed secondary motion, while games need the body and cloth to run within a fixed performance budget and may use real-time simulation rather than baked caches. Adjust the workflow to the constraints of the delivery format, and be explicit about any trade-off, such as accepting a small cloth error on a distant shot to keep the cache size manageable.

08Common mistakes and how to prevent them

• The most common mistake is simulating too early. Running cloth or hair on blocking poses produces motion that is then hard to correct once the animation is refined. Prevent this by writing the rule into the workflow: no simulation caches until the body timing is locked for the shot.
• Another frequent problem is hiding errors with manual keys on top of a cache. A small pop can be patched with a key, but the patch will break as soon as the animation or cache changes. Fix the cause in the simulation settings, the collision proxy, or the rig, and keep manual corrections to a minimum that is documented in the shot log.
• Teams also lose time by ignoring units and frame rates. A scene built in centimeters and imported into a meter-based scene will produce solver results that look plausible but are scaled wrong. Check units, scale, and frame rate in the first step of setup, and confirm them again before the final export.

09Practical checklist

• Shot breakdown written with key poses, beats, camera angles, and simulated elements listed.
• Rig and asset versions confirmed, with units, scale, and frame rate matching the production standard.
• Simulation order agreed and written down for animation, proxies, cache, and polish.
• Blocking approved at playable speed from the shot camera before detail work starts.
• Collision proxies tested against the animated pose at elbows, knees, shoulders, and hips.
• Cache built on a fixed frame range with the animation version recorded in the cache name.
• Standard quality checks completed for foot sliding, popping, jitter, interpenetration, and root changes.
• Shot log updated with versions, settings, frame range, cache location, and accepted issues before handoff.

★Learning sources

• Micro Degree: Character Animation and Simulation
• Micro Degree: 2D Animation Fundamentals
• Micro Degree: 3D Animation Techniques
• Micro Degree: Illustration Fundamentals