P nder is a real-time system for tracking people and in-
terpreting thier behavior. It runs at 10Hz on a standard
SGI Indy computer, and has performed reliably on thou-
sands of people in many di erent physical locations. The
system uses a multi-class statistical model of color and
shape to obtain a 2-D representation of head and hands
in a wide range of viewing conditions. P nder has been
successfully used in a wide range of applications including
wireless interfaces, video databases, and low-bandwidth
coding.