Population aging is a current social factor which impacts significantly on the future of most countries. To relieve such economic and social pressures

one feasible way is to automatically understand the activities of daily living (ADL) of eldly people by using the highly developed information and communication techniques

so as to provide living assistance for eldly people to prolong their independent living time in home. ADL happens under unstructured natural environment. ADL recognition and understanding is actually a process of observation

analysis

inference and decision in space-time domain under dynamic environment. It essentially requires that the computer system should have the human-like cognitive competence. Therefore

ADL recognition and understanding is a confluence of interdisciplinary research (such as computer vision

cognitive computing

and pervasive computing) and real-world applications to cope with the problem of population aging. The goal of this paper is to discuss the challenges and basic scientific problems in ADL recognition and understanding

and to discuss possible future directions to reduce the gap between the start-of-art and requirements of ADL recognition in real world.