This paper presents a real-time human figure motion control method using color blob tracking, and human motion synthesis based on real-time inverse kinematics. Our purpose is to do seamless mapping of human motion in the real world into virtual environments. In general, virtual environment applications such as man-machine 'smart' interaction require real-time human full-body motion capturing systems without special devices or markers. However, since such vision-based human motion capturing systems are essentially unstable and can only acquire partial information because of self-occlusion, we have to introduce a robust pose estimation strategy, or an appropriate human motion synthesis based on motion filtering. In this paper, we have demonstrated a real-time and online real-virtual interaction system which realizes human full-body motion capturing and synthesis.