Humans are the most commonly seen moving objects in one's daily life. Yet, the detection and recognition of these commonly seen moving objects are still unexplored questions in the area of computer vision. The project on human body motion analysis was started ten years ago. Currently, a third generation system called First Sight has just been completed. The main goal of this project is to develop algorithms that can analyze human body motion from the lowest pixel level to the highest syntactic level. First Sight is able to perform the task equivalent to a three months of baby, i.e. able to track moving human objects and to label the moving limbs. Future work in this project will be focused on the high level analysis of the motion information.