Video & Tracking¶
SAM2 Track¶
Track objects across timelapse frames using SAM2.
Details
Connect reference masks from SAM2 Segment (frame 1) and an image stream (e.g. VideoIterator or FolderIterator → ImageReader).
| Direction | Port | Type |
|---|---|---|
| Input | image |
image |
| Input | label_image |
label_image |
| Output | mask |
mask |
| Output | label_image |
label_image |
| Output | overlay |
overlay |
Properties: Model, Mode, Min Score, Min IoU, Dormant Frames, Appearance Wt
Video to Frames¶
Extract frames from a video file and save as numbered images.
Details
Select a video file and an output folder. Run the node once to export all (or a range of) frames as individual image files.
| Direction | Port | Type |
|---|---|---|
| Output | folder_path |
path |
Properties: Format
Particle Linker¶
Link particle detections across video frames into tracks.
Details
Takes a regionprops table (frame, centroid_y, centroid_x columns) and assigns a track_id to each detection so the same physical particle shares one ID across all frames.
Uses nearest-neighbor linking (Hungarian algorithm) with gap-closing. Unlinked detections get track_id = -1.
| Direction | Port | Type |
|---|---|---|
| Input | table |
table |
| Output | table |
table |
Properties: Max Displacement (px), Max Gap (frames), Min Track Length, Area Weight
Track Properties¶
Compute per-track statistics from a linked particle table.
Details
Input must have track_id, frame, centroid_y, centroid_x columns (output of Particle Linker).
Output columns: track_id, n_frames, duration, total_path, net_displacement, confinement_ratio, mean_speed, max_speed, diffusion_coeff, alpha (anomalous exponent).
Motion type interpretation of alpha: alpha ≈ 1 → Brownian diffusion (random walk) alpha < 1 → Confined / sub-diffusion (tethered, corralled) alpha > 1 → Directed / super-diffusion (motor-driven transport)
| Direction | Port | Type |
|---|---|---|
| Input | table |
table |
| Output | table |
table |
Trajectory Plot¶
Draw particle trajectories as colored paths on a background image.
Details
Connect a reference image (e.g. first frame or overlay) and the linked table from Particle Linker. Each track gets a distinct color.
Parameters: Tail Frames — 0 = show full history; N = show last N frames only Color By — track_id (fixed color) or speed (red=fast, green=slow) Show IDs — label each track with its ID number
| Direction | Port | Type |
|---|---|---|
| Input | image |
image |
| Input | table |
table |
| Output | image |
image |
Properties: Tail Frames (0=all), Line Width, Color By, Show IDs
Track Filter¶
Filter a linked particle table by per-track statistics.
Details
Removes rows belonging to tracks that fall outside the specified min/max bounds. Unlinked rows (track_id = -1) are always kept unless 'Drop Unlinked' is checked.
Set any bound to 0 to disable that limit.
| Direction | Port | Type |
|---|---|---|
| Input | table |
table |
| Output | table |
table |
Properties: Min Length (frames), Max Length (frames), Min Net Disp (px), Max Net Disp (px), Min Mean Speed, Max Mean Speed, Drop Unlinked (track_id=-1)
MSD Analysis¶
Compute Mean Squared Displacement (MSD) vs lag time for all tracks.
Details
MSD(τ) = <|r(t+τ) − r(t)|²> averaged over all track-time-origin pairs.
Output table columns: lag, msd_ensemble, n_samples, plus per-track columns if 'Per Track' is checked.
Interpretation: log-log slope (alpha) ≈ 1 → Brownian diffusion alpha < 1 → Confined motion (sub-diffusion) alpha > 1 → Directed transport (super-diffusion)
| Direction | Port | Type |
|---|---|---|
| Input | table |
table |
| Output | table |
table |
| Output | plot |
plot |
Properties: Max Lag (frames, 0=auto), Per-Track MSD columns