Markers / distance / angle

Two independent tools for annotating and measuring your images: a distance/angle ruler, and persistent point markers.

Open via Plot → Markers / distance / angle (Ctrl+Shift+T).

The Measure distance and angle panel showing populated Delta x, Delta y, Length and angle readings, with a dashed measurement line and star-shaped markers on the image — The **Measure distance & angle** panel with a live measurement: a dashed line drawn between two points (right) and its distance/angle readings (left), plus a few point markers (the star symbols).

Measuring distance and angle

Click Draw line and draw across the two points you want to measure. The panel reports:

Reading	Meaning
Delta x / Delta y	Horizontal and vertical offset between the two points.
Length	Straight-line distance.
Angle to horiz. (deg)	Angle relative to the horizontal.
Angle to vert. (deg)	Angle relative to the vertical.

Placing markers

Markers highlight specific points of interest in the image.

Click Set markers, then left-click each point you want to mark; right-click to finish.
Display markers toggles their visibility.
Click Clear markers to remove them all.

Markers can outlive a session Enable Hold markers to keep your markers even after starting a new session — they're only cleared when you restart PIVlab itself.

The Display average button shows the mean image across all loaded frames — handy for placing markers on a feature that's clearer in the time-averaged view than in any single frame.