Streamlines

Streamlines trace the instantaneous flow direction through your vector field. Open via Plot → Streamlines.

Streamlines are global Once drawn, streamlines apply to every frame in the session, not just the one you drew them on.

PIVlab Stream lines panel — The **Stream lines** panel.

Drawing streamlines

Button	How it works
Draw stream lines	Click to place a streamline's starting point; every click adds another. Right-click to finish.
Draw stream line rake	Click once for the rake's start point, once more for its end point — PIVlab spaces Amount of stream lines on rake (default 10) evenly along that line.
Draw streamslice	Automatically fills the entire field with streamlines using MATLAB's `streamslice`, at a density you set (default 1 — higher values draw more streamlines).

hold streamlines (on by default) adds each new streamline to the existing set instead of replacing it — turn it off if you want each draw action to start fresh. Click Delete all stream lines to clear everything.

Yellow streamlines tracing the flow direction, drawn on top of a velocity-magnitude colour overlay — Streamlines (yellow) tracing the flow, here drawn over a velocity-magnitude overlay. They can be combined with any derived parameter in the background.

Styling

Choose a Color (yellow, red, blue, black or white) and Line width (1–3), then click Apply color and width.