Recently, three-dimensional computer graphics(3D CG)technology has been frequently used in the field of video production for commercials, TV programs and motion pictures. one new trend in video production using 3D CG is creating images composed of 3D CG and live action images taken by a video camera. However, generating photo-realistic 3D CG in real time poses difficult problems due to the amount of computation required. We developed a real time virtual studio for video program production, which achieves composition of live action images and Photo-realistic 3D CG in realtime. The realtime virtualstudio uses 3D CGto generate a virtual 3D studio set or background Which moves corresponding to the pan, tilt and zoom of an actual video camera. people and objects filmed in front of a blue background with a video camera are combined with three dimensional images in real time, In this paper, we describe the real time virtual studio capable of producing photo-realistic 3D CG.