Diagrams illustrating how the dynamic tracking parameters operate (pairs that satisfy the respective criteria are shown in violet, the ones that do not in gray): (a) the dynamic search radius R_dyn, which defines the area the algorithm searches for candidate pairs or detections. It depends on the distance d between the candidate track’s pair p_pair closest in time to the investigated step, and the predicted position p_fit(t_i) where the next pair is expected to lie according the curve (black, partly dashed line) fitted to the track (orange path). The relation between R_dyn and d is that of an arctangent (see Eq. (2)) shown by the graph on the right. (b) the (maximum) offset angle Ω, which defines a circular sector within which candidate pairs or detections must lie. The sector originates from the candidate track’s closest pair and opens up in the same direction as the fitted curve at the investigated time-step (v_fit(t_i), black arrow). The offset angle also depends on d in the form of an arctangent, although reversed, as shown by the graph on the right (see Eq. (3)). (c) the (maximum) inclination angle I, whose value is equal to that of Ω. It defines the maximum inclination candidate pairs can have with respect to v_fit(t_i). (d) the relative difference in speed ΔV, which determines how much the speed of a candidate pair can relatively deviate from |v_fit(t_i)|. The relation between ΔV and |v_fit(t_i)| is also that of a reversed arctangent as shown by the graph on the right (see Eq. (4)).