Joint NTU-UBC Research Centre of Excellence in Active Living for the Elderly (LILY), and School of Computer Engineering, Nanyang Technological University, Singapore.|Institute for Infocomm Research (I2R), Agency for Science, Technology and Research (A*STAR), Singapore.|Joint NTU-UBC Research Centre of Excellence in Active Living for the Elderly (LILY), and School of Computer Engineering, Nanyang Technological University, Singapore.|Institute for Infocomm Research (I2R), Agency for Science, Technology and Research (A*STAR), Singapore.|Institute for Infocomm Research (I2R), Agency for Science, Technology and Research (A*STAR), Singapore.