Abstract: The simulation regarding the state change of the subject in a real space provides a system which represents impacts to three-dimensional computer graphics caused by changes of state of three-dimensional computer graphics composed and fixed to subject, and state of image taking space by simulation, surface polygon model and similar surface polygon model 1 is selected, according to shape pattern, from surface polygon model 2 measures, in a three-dimensional way, subject image existing in the same space, a tracking process is performed on the computer graphics, following to the relative position change of the position changes of the subject and the camera caused in real three-dimensional space, subjects in the visual field of the camera and virtual three-dimensional computer graphics image is unified and displayed by displaying computer graphics image having the same relative position change on the image.