The ratio of apparent size of a virtual object to a actual object is measured. A concrete and an abstract object were presented in a virtual or a real space which was constructed using a rectangular paralleleplped with a viewing window. Virtual objects were modeled and rendered using a computer and presented on the CRT screen. Five subjects who could easily view a 3D image participated in the experiment. Distance from eyes to the object was varied among 50,75,100,130 and 175 cm. Results showed that the apparent size of virtual objects was expressed by the exponential function of distance and the difference of apparent size ratio between concrete and abstract objects was little.
