A visual simulator was developed to synchronize the subject's walking motion on the treadmill with the video image shown on a HMD. Its validity was examined by comparing the accuracy of distance estimation with the conventional video image without walking motion. To investigate the influence of environmental features the subjects were asked to "walk" through a path consisted of two spaces of different physical feature, and to show the proportion of the length of two spaces. As a result, it is found that a narrow and small space tends to be perceived longer.
