Fig. 7
The algorithm functionality is shown based on Al\(_2\)O\(_3\) particles. a A zoom-in of a high-speed camera frame is shown. The x and y positions of the particle centers at the time step i are automatically detected with sub-pixel accuracy. If the center does not move beyond the inter-frame distance threshold shown by the white circle in the next frame at the time step i+1, it is assigned to the same trajectory. b Connecting the particle positions across consecutive frames based on this detection method and the inter-frame particle distance threshold allows the reconstruction of the trajectories. This is shown schematically for one upward-moving and one downward-moving particle. A particle also present in the frames and detected with sub-pixel accuracy, but not assigned to these two trajectories, is shown in gray.
