There is an error in the first sentence of the Evaluation Metrics subsection of the Experiments section. The correct sentence is: As accuracy measures, we adopt the metrics proposed in \[3\] and extended in \[12\]: we consider a group as correctly estimated if at least ⌈(T ⋅ ∣G∣)⌉ of their members are found by the grouping method and correctly detected by the tracker, and if no more than (1−T) ⋅ ∣G∣ false subjects (of the detected tracks) are identified, where ∣G∣ is the cardinality of the labelled group G, and T Є \[0,1\] is an arbitrary threshold, called tolerance threshold.
