In this paper we deal with a remote meeting system with tangible interface, in which a robot is used as tangible avatar instead of a remote meeting partner. For realizing such system, it is a critical issue how the robot imitates human motions with natural and exact. So, we suggested a new method that human arm motion is captured with a stereo vision system and transferred to the robotic avatar with real-time. For capturing 3D arm motions based on markerless method, we proposed a new metaball-based method which was designed in order to have some robust and efficient properties: a modified iso-surface equation of metaball for overcoming local minima and a downsizing method of 3D point cloud for improving time complexity. With our meeting system, we have implemented our new algorithm and run at approximately 12–16 Hz. Also, its accuracy in motion capturing could be acceptable for robot motion generation.