GRF Vector Overlay

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About this tool

Overlay a ground reaction force vector on sagittal-view video. Force magnitude scales the arrow length; direction is fixed vertical (upward from the foot). Designed for teaching kinetics: students see how big the force is, when it peaks, and where it acts.

Load video — sagittal view (side on). Best with a slow-motion jump or landing.
Load force CSV — auto-detects vertical force columns (Fz, vGRF, etc.). 3-axis files: only vertical is shown.
Sync — scrub video to the visible peak force frame, click Sync to peak. The CSV peak aligns to that frame.
Anchor — click on the foot position in the video. The vector base sits there.
Play — vector updates live. Export side-by-side figure.

1Video

No video loaded.

2Force data

Load video first.

3Sync

Scrub the video to a frame where the force visibly peaks (e.g. mid-landing). Then click below — we align the CSV's maximum force to that frame.

Not synced.

4Anchor point

Click on the video where the foot contacts the ground. The vector will extend upward from there.

No anchor set.

5Display

Vector colour

Vector scale 30% of frame

Length of arrow at peak force, as % of video height.

Show label

Current force

—N

Peak in trace

—N

Peak × BW

—

▶

Load a video to begin

0.000 s