Table 2.

Parameters to score the difficulty of a tracking problem. Mean NN denotes the mean nearest neighbor distance between particles in a frame.

	Participating Particles per Frame	Mean Displacement / Mean NN	Search Radius / Mean NN	# Triplets Each Particle is in [mean / max]	# Candidate Triplets	% Particles Participating in >1 Triplets
1) Rotating Ball	176	0.2	0.5	1.1 / 3	178	3%
2) Flock of Birds	38	0.3	0.5	1.1 / 2	27	4%
3) School of Fish	131	0.3	0.6	1.5 / 6	151	44%
4) Rotating Dish	80	0.8	1.3	7.1 / 20	555	87%
5) Particle Image Velocimetry	1304	1.1	2.2	24.1 / 120	25128	98%
6) 3-Polar Mitotic Spindle	299	0.4	0.9	2.3 / 12	567	63%
7) 2-Polar Mitotic Spindle	880	0.7	1.3	2.6 / 18	1688	69%