Table 1: Ball classification performance using SIFT and different number of clusters in the -means algorithm on whole dataset.

SIFT descriptors length TP FN TN FP Detection rate (%) 10 579 658 988 249 63.33% 20 621 616 1059 178 67.90% 30 558 579 1056 181 65.23% 40 519 718 1091 146 65.07%