1. Introduction
Gait refers to the characteristics of a person while walking. Like many other biometric features (iris, fingerprint, face, hand writing, etc.), human gait can be used for identification [37]. From those biometric patterns, only gait information is robust enough to camera distance and low image resolution. Because of these advantages, research on gait recognition is becoming more and more popular and has also made great progress in recent years [25], [37], [38], [43], [46].