\\textbf{Left}: A sample frame of the Dancing video. The provided bounding boxes were used instead of running the \ntracking/segmentation algorithm. \\textbf{Center}: Affinity matrix. \\textbf{Right}: Binarized affinity matrix after applying the threshold $\\tau = 0.9/4 = 0.225$. Note that some entries are a little smaller than the threshold $0.225$, thus binarized to be $0$. \nBut the grouping result is still correct since persons are grouped as connected components. One single group is correctly detected. \n(This is a color figure.)