1. A human activity modeling method comprising: determining, by a controller, principal components of at least one of depth and binary shape images of human activities extracted from video clips; determining, by the controller, Independent Component Analysis (ICA) representations based on the principal components; determining, by the controller, features through Linear Discriminant Analysis (LDA) based on the ICA representations; determining, by the controller, a codebook using vector quantization; determining, by the controller, observation symbol sequences in the video clips; and learning, by the controller, human activities using a Hidden Markov Model (HMM) based on a status transition and an observation matrix.