Points node
Track Points
Finds and follows trackable pixels in any image or live video -- corners and texture features (Shi-Tomasi), evenly spread by Min Distance up to Max Points (Distance Variance breaks the spacing's regularity for an organic layout), then tracked frame-to-frame with pyramidal optical flow so every point keeps its identity. Outputs a live point cloud with per-point Velocities (the scene's real motion), Activities (feature strength) and Ages (seconds tracked) -- for Plexus, particles, Replicator, ropes. A Mask limits where detection happens. Track off = fresh detection every frame.
Inputs
| Port | Type | Default |
|---|---|---|
| ImageThe picture to analyse — camera, video or any generator. Its corners and texture knots become the trackable points; the image itself is not drawn. | image | — |
| EnableOff empties the point cloud and resets every track, so switching back on starts detection from scratch. | bool | true |
| Max PointsUpper limit on how many points are followed at once. Clamped to 1…1024; more points cost more GPU time every frame. | int | 256 |
| Min DistanceSmallest spacing allowed between points, in Grafit units. Held at 0.005 or above — large values spread points out, small ones let them crowd onto texture. | float | 0.08 |
| Distance VarianceBreaks the regularity of that spacing so the layout looks organic instead of gridded. Clamped to 0…1. | float | 0 |
| QualityHow strong a corner must be before it is worth tracking. Clamped to 0.001…1; low values grab faint texture, high values keep only hard corners. | float | 0.1 |
| TrackOn, each point follows the motion and keeps its identity, velocity and age. Off, points are detected fresh every frame and jump around. | bool | true |
| SmoothingDamps the frame-to-frame jitter of each point's position. Clamped to 0…0.95; the higher it goes, the more the points lag behind real motion. | float | 0.3 |
| ResolutionSize of the analysis grid along the image's long edge, in texels. Clamped to 64…1024 — finer grids find smaller features but cost more. | int | 384 |
| MaskOptional image limiting where detection may happen. Bright areas allow points, dark areas block them; connect any generator or camera texture. | image | — |
| Mask ModeWhich channel of the mask image is read — Alpha, Red, Green, Blue or Luminance. Out-of-range values snap to the nearest channel. | int | 0 |
| Mask InvertFlips the mask so points are detected where it was dark instead. | bool | false |
Outputs
| Port | Type |
|---|---|
| Points | structure |
| Velocities | structure |
| Activities | float |
| Ages | float |
| Count | int |
How It Works
Track Points finds and follows trackable pixels in any image or live video, entirely on the GPU. Detection is Shi–Tomasi corner scoring — the classic "good features to track" measure — spread out by Min Distance through detection binning, with Quality acting as a fraction of the frame's best feature so the threshold follows the scene. Tracking is pyramidal Lucas–Kanade: each point is matched into the next frame across a resolution pyramid, so fast motion is still caught.
Points keep stable SLOT identity while they survive, and lost tracks are refilled deterministically, so index-based consumers downstream stay coherent. With Track off, the node simply detects fresh features every frame.
Outputs
- Points — the tracked cloud, in Grafit units.
- Velocities — per-point motion, the scene's real movement as data (feed it to Points to Notes for motion-driven dynamics, or to a particle field).
- Activities — per-point feature strength.
- Ages — seconds each point has been tracked; old points are the stable structure, young ones the new arrivals.
Use Cases
- Optical-flow visuals — draw the cloud with Points Visualize, or connect Plexus for a web that follows the scene.
- Motion as music — Velocities into Points to Notes makes real movement the velocity of the notes.
- Camera-driven forces — use the cloud as a particle Custom Points shape or a Find Neighbors target.
Tips
- The Mask input is continuous: grey weakens detection, and a segmentation mask isolates a person from the background.
- Smoothing shapes the OUTPUT only — the tracker never loses its feature to it.
- Analysis Resolution (64–1024) trades precision for cost; the whole node is Metal compute and runs sub-millisecond with no CPU stall.
Open Track Points in the interactive catalog →
Track Points is one of 381 nodes in Grafit Pro.
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