Half the pain of mocap cleanup is avoidable, and it usually comes down to the basics being wrong before anyone touches a curve. Wrong up-axis, mismatched scale, garbage bone names, feet that never plant. If you are a tech artist preparing data, or sending it to a cleanup service, working through a checklist first saves hours of confused back-and-forth. Here is the practical, no-fluff list we run for FBX mocap cleanup and C3D data, plus exactly what to send a service to get the best result back.
1. Coordinate system, up-axis, and scale
This is where most “the animation imported sideways” tickets come from. Nail it first:
- Up-axis — Maya and most FBX pipelines are Y-up; many capture tools and Blender default to Z-up. Decide on one and convert intentionally, not by eyeballing a rotated import.
- Scale and units — confirm whether the file is in centimeters or meters. A 100x scale mismatch is the classic reason a character is suddenly a giant or an ant, and it wrecks foot-contact math.
- Forward axis — know which way the character faces at the origin so root motion does not march off in the wrong direction.
2. Skeleton mapping and bone naming
Retargeting lives or dies on a clean skeleton. Before anything else:
- Confirm the hierarchy is intact, with one clear root and no stray or duplicate joints.
- Use consistent, descriptive bone names (for example a clear left/right convention) so auto-mappers and IK retargeters find joints without manual fixing.
- Check the bind/rest pose — a clean T-pose or A-pose frame makes mapping and retargeting far more reliable.
- Note the joint count and orientation so the source and target rigs line up.
3. Foot contacts and ground
Feet are the first thing viewers judge. Every markerless capture needs this pass:
- Find and mark foot-plant frames where each foot should be locked to the ground.
- Kill foot-slide so planted feet do not drift.
- Fix ground penetration and floating so the character sits on the floor plane, not through or above it.
- Verify the floor height matches your scene origin.
4. Jitter filtering, without killing the life
Markerless solves carry high-frequency noise. The goal is to remove jitter while keeping the snap and weight of the performance:
- Apply smoothing filters per channel rather than one blanket filter that flattens everything.
- Watch for limb pops at knees and elbows, common solve artifacts that filtering alone will not fix and that often need a hand-keyed correction.
- Over-smoothing turns a punch into a wave; protect the fast frames.
5. Root motion
Decide early whether each clip is root motion or in-place, because it changes how you process the root and feet:
- For root motion, project horizontal travel onto the root bone cleanly and keep vertical bob sensible.
- For in-place, zero out root translation so engine code can drive position.
- Keep the root orientation stable so turns read correctly.
6. Export settings: FBX and C3D
Get the export right so the next tool does not silently re-break your work:
- Bake animation to the target frame rate and confirm the frame range.
- For FBX, set the correct up-axis and units on export, bake transforms, and avoid embedding unnecessary mesh if you only need motion.
- For C3D, keep the marker data and labels intact for downstream solving, and document the units.
- Name the file with the take, character, and version so nothing gets confused in a batch.
7. A real QC pass
Before you call it done, play it back at speed and at the speed it matters: framerate, in-engine, and from the camera the shot uses. Look for the usual suspects: sliding feet, popping joints, penetration, and any frame where the smoothing flattened a beat. A short checklist beats a re-do. Our AI mocap cleanup guide goes deeper on the full remote workflow if you want the longer version.
What to send a cleanup service
The fastest, cheapest turnaround comes from giving a service everything it needs up front:
- The raw capture (FBX, BVH, C3D, or the source video for a fresh solve) with units and up-axis stated.
- Your target rig or skeleton, ideally with a bind pose, so retargeting matches your character exactly.
- A note on root motion vs in-place per clip.
- Your engine and frame rate, plus the desired delivery format.
- Any reference of how the move should feel, so the cleanup keeps the right beats.
That package is exactly what our motion capture cleanup and retarget service is built to take in and return engine-ready.
Frequently asked questions
Why does my mocap import sideways or at the wrong size?
Almost always an up-axis or unit mismatch. Many capture tools and Blender are Z-up while Maya and most FBX pipelines are Y-up, and a centimeters-versus-meters mix causes a 100x scale error. Confirm both before importing and convert on purpose rather than rotating and scaling by eye.
Can jitter filtering fix limb pops on its own?
Not usually. Smoothing reduces high-frequency jitter, but knee and elbow pops are solve artifacts that often need a hand-keyed correction. Over-filtering also flattens the fast frames that give motion its snap, so it is a targeted fix, not a blanket one.
What is the most important thing to get right before retargeting?
A clean skeleton with consistent bone names, an intact hierarchy, and a good bind pose. Retargeting and auto-mapping depend on it, and fixing names and hierarchy after the fact is far slower than getting them right first.
What should I send to get the best cleanup result?
Send the raw capture or source video with units and up-axis stated, your target rig with a bind pose, a root-motion-or-in-place note per clip, your engine and frame rate, and any reference for how the move should feel. That package lets a service deliver engine-ready clips without guesswork.
If you would rather hand off a clean, documented package and get back motion that drops straight into your engine, that is what we do. Send us your captures and your rig, and we will run the full checklist and return it engine-ready. Get a free quote.
