Abstract

Using computers to watch human activity has proven to be a research area having not only a large number of potentially important applications (in surveillance, communications, health, etc.) but also one the had led to a variety of new, fundamental problems in image processing and computer vision. In this chapter we review research that has been conducted at the University of Maryland during the past five years on various topics involving analysis of human activity.

Introduction

Our interest in this general area started with consideration of the problem of how a computer might recognize a facial expression from the changing appearance of the face displaying the expression. Technically, this led us to address the problem of how the non-rigid deformations of facial features (eyes, mouth) could be accurately measured even while the face was moving rigidly.

In section 10.2 we discuss our solution to this problem. Our approach to this problem, in which the rigid head motion is estimated and used to stabilize the face so that the non-rigid feature motions could be recovered, naturally led us to consider the problem of head gesture recognition. Section 10.3 discusses two approaches to recognition of head gestures, both of which employ the rigid head motion descriptions estimated in the course of recognizing expressions.