SimpleLevelSeqSmooth User Guide

Level sequence data filtering plugin with 12 smoothing algorithms covering mocap, post-processing, and AI scenarios.

• Unreal Engine 5.2–5.8
• Version 1.1.0 (Version 2)

• 12 Smoothing Algorithms covering time-domain, frequency-domain, state estimation, adaptive, and AI-specific approaches
• Content Browser Integration: Right-click on LevelSequence assets to access smoothing
• ControlRig Support: Directly processes ControlRig parameter sections (Transform and Scalar)
• Flexible Output: Choose to overwrite the original sequence or create a new one
• Batch Processing: Process multiple sequences at once with consistent suffix naming
• Auto Frame Rate Detection: Automatically reads the sequence frame rate

1. Copy the SimpleLevelSeqSmooth folder to your project’s Plugins/ directory
2. Restart the Unreal Editor
3. Enable the plugin in Edit > Plugins if not already enabled

1. In the Content Browser, right-click on one or more LevelSequence assets
2. Select Smooth from the context menu
3. Choose a smoothing algorithm and adjust parameters
4. Select output mode (overwrite or create new)
5. Click OK to apply

#	Algorithm	Category	Key Advantage	Best For
1	Moving Average	Time-domain	Simplest, zero configuration	Quick preview
2	Gaussian	Time-domain	Velocity/acceleration curves also smooth, no abrupt changes	Large joints (arms, legs)
3	Exponential	Time-domain	Recent data weighted more, fast response	Real-time preprocessing
4	Median	Time-domain	Only filter that cleanly removes impulse noise / frame jumps	Mocap data first pass
5	Bilateral	Time-domain	Smooths noise while preserving sudden stops / motion edges	Actions with clear start/end
6	Butterworth Low-pass	Frequency-domain	Precise cutoff frequency, zero-phase no delay	Joint data (recommended)
7	Wavelet Denoising	Frequency-domain	Multi-scale separation, automatic noise level estimation	Fine joints / compound noise
8	Kalman	State Estimation	Combines smoothing with velocity prediction, optimal estimate	Trending motion data
9	One Euro	Adaptive	Strong smoothing at rest, weak at fast motion, minimal latency	VR / AR / real-time interaction
10	Complementary	Adaptive	Fuses integration path + direct measurement, zero-phase	IMU inertial mocap
11	Savitzky-Golay	Polynomial	Precisely preserves peaks and inflection points	Fine joints (fingers)
12	Confidence-Weighted	AI-specific	Auto-detects outlier frames and reduces their weight	AI pose estimation

The parameter names below match those shown in the editor dialog.

Arithmetic mean over a sliding window.

Parameter	Default	Range	Description
Window Size	51	3–501 (odd)	Number of frames to average, larger = smoother

Gaussian distribution weighted average, center-weighted with symmetric falloff.

Parameter	Default	Range	Description
Window Size	51	3–501 (odd)	Reference frame range
Sigma	12.0	0.1–100	Gaussian width, recommended 1/6–1/3 of window size

Exponentially weighted recursive filter, recent data weighted more.

Parameter	Default	Range	Description
Alpha	0.15	0.01–1.0	Smaller = smoother: 0.01 = strong, 0.15 = recommended, 0.5 = weak

Selects the middle value in a sliding window, best for impulse noise and frame jumps.

Parameter	Default	Range	Description
Window Size	51	3–501 (odd)	Larger window removes more noise but loses detail

Weights by both spatial distance and intensity difference, edge-preserving.

Parameter	Default	Range	Description
Window Size	51	3–501 (odd)	Spatial reference range
Spatial Sigma	12.0	0.1–100	Controls spatial smoothing range, larger = smoother
Range Sigma	0.5	0.001–100	Controls intensity tolerance, larger = ignores edges, smaller = preserves edges

Second-order frequency-domain filter with zero-phase bidirectional processing.

Parameter	Default	Range	Description
Cutoff Frequency (Hz)	10.0	0.1–60	Motion below this frequency is preserved. Human body < 6 Hz, fingers < 10 Hz
Sample Rate (Hz)	Auto	1–1000	Auto-filled from sequence frame rate; can be changed manually if needed

Haar wavelet transform + MAD noise estimation + soft thresholding.

Parameter	Default	Range	Description
Decomposition Level	4	1–10	More levels = wider frequency range processed, typically 3–5
Threshold Coefficient	0.5	0.01–5.0	< 1 preserves more detail, 1 = standard, > 1 = stronger denoising

Optimal state estimation based on constant-velocity motion model (position + velocity).

Parameter	Default	Range	Description
Process Noise (Q)	0.01	0.0001–10	Motion model uncertainty, larger = trusts measurement more (tighter tracking)
Measurement Noise (R)	0.1	0.0001–100	Sensor/mocap noise level, larger = stronger smoothing

Adaptive cutoff frequency low-pass filter (CHI 2012), strong smoothing at rest, weak at fast motion.

Parameter	Default	Range	Description
Min Cutoff	1.0	0.001–30	Cutoff frequency at rest, smaller = smoother when still
Speed Coefficient (Beta)	0.007	0–1.0	Speed influence on cutoff: 0 = fixed low-pass, > 0 = reduces smoothing at fast motion
Derivative Cutoff	1.0	0.001–30	Smoothing of the speed estimate itself, usually keep default
Sample Rate (Hz)	Auto	1–1000	Auto-filled from sequence frame rate

Forward-backward complementary filter, fuses integration path and direct measurement, zero-phase.

Parameter	Default	Range	Description
Complementary Alpha	0.98	0.5–0.999	Larger = trusts integration (preserves detail), smaller = trusts measurement (suppresses drift). Recommended 0.95–0.99

Local polynomial fitting that preserves peaks and inflection points while smoothing.

Parameter	Default	Range	Description
Window Size	21	5–501 (odd)	Local fitting range
Polynomial Order	3	2–6	Fit degree: 2 = parabola, 3 = cubic (recommended), 4 = quartic

Auto-detects outlier frames using MAD robust statistics and reduces their weight. Normal frames are smoothed lightly, while anomalous frames receive stronger corrections.

Parameter	Default	Range	Description
Window Size	51	3–501 (odd)	Local analysis and smoothing range
Sensitivity	2.0	0.1–10	Frames beyond this many standard deviations are flagged. Smaller = more sensitive: 1.5 = sensitive, 2.0 = standard, 3.0 = lenient

• ControlRig plugin (enabled by default)

• Unreal Engine 5.2–5.8

Open Edit → Project Settings, select the Simple Level Sequence Smooth settings page, and set Language to English or Chinese. English is the default. Available user-facing UI, tooltips, notifications, and functional logs update immediately without restarting the editor. Public API names and module startup/shutdown logs remain in English.

For usage questions or collaboration, please visit the contact page.

• Contact: Contact and collaboration