Inspired by Posy's "motion extraction" video — that beautiful trick where a video is differenced against a time-shifted copy of itself, leaving only what moved. Trees breathing. Sun creeping across a wall. A deer you couldn't see until now.
I rebuilt it in TouchDesigner as a single drop-in TOX so you can wire any video, webcam, or live source into it and start hunting hidden motion in seconds.
How to use
- Drag motion_extract.tox into your network.
- Wire your source (movieFileIn / videoDeviceIn / Render TOP / NDI — anything) into its first input.
- Open the TOX's parameters. Five pages of controls.
Quick start
- Time → Offset Frames — the heart of the effect. 1 = sharp frame-to-frame motion. 30 = ~1 second offset, plants and shadows start moving. 150 = 5+ seconds, the sun visibly travels.
- Time → Smoothing — leave at 0.85. This is what stops the per-frame flicker; it accumulates motion over time using a max-blend feedback loop.
- Mask → Gain / Sensitivity — crank these to amplify subtle motion. Gain 6, Sensitivity 1 is a good start.
- Mask → Blur Size — adds bloom/feature size. Higher = larger blobs of motion, less noise.
- Glow → Glow Amount — set to 0.3+ for that ghostly trail look from the video.
- Output → Output Mode — Motion Only for pure black-and-white motion. Additive to overlay motion on top of the original picture.
Tips
- For wind / clouds / slow phenomena: Offset Frames 60–150, Smoothing 0.9, Gain 8.
- For sharp gesture detection: Offset Frames 1, Smoothing 0.5, Threshold 0.05.
- For the artistic RGB chromatic-shift look: turn Monochrome off, raise Tint Mix.
- Mount a tripod. The whole effect depends on a stable frame — handheld footage needs stabilization first.
The cache holds 300 frames by default (≈10 sec at 30 fps). Bump Cache Size for longer offsets.
Have fun finding the invisible.
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