Zongyi Liu Sudeep Sarkar Effect of silhouette quality on hard problems in gait recognition. 170-183 2005 35 IEEE Transactions on Systems, Man, and Cybernetics, Part B 2 http://dx.doi.org/10.1109/TSMCB.2004.842251 db/journals/tsmc/tsmcb35.html#LiuS05