In numerous content-based video applications, it is important to extract fr
om a video sequence a representation for humans in motion. This task is dif
ficult, because humans are not rigid objects and they are capable of perfor
ming a wide variety of actions. However, often, human movements can be cate
gorized into repetitive and rhythmic patterns of motion. Identifying the mo
tion pattern of a human significantly alleviates the task of construction o
f its representation. We propose here a model-based recognition of the gene
ric posture of human walking in dynamic scenes. We model the human body as
an articulated object connected by joints and rigid parts, and model the hu
man walking as a periodic motion. The recognition task is to fit the model
walker sequence to the walker in the live video (data walker sequence). We
achieve this by determining the period of the data walker sequence and find
ing its phase with respect to the model walker sequence. We present promisi
ng results of how our system performs with a live video sequence.