Movie 1.

Calibrating the LSI method via a quasi-2D setup: 10-minute recording of the backscattered speckle pattern and side particle movement induced by a worker ant buried under 5 cm of dry glass beads in a quasi-2D container (5 × 6 × 0.5 cm³). Plots depict mean absolute pixel intensity change over time, detonated as <|dI/dt|>.