Abstract
A vertical square figure (2.5m×2.5m) is observed through the following various manner: 1. The square is observed straightly at the bottom while subject is moving. 2. The square is observed straightly at a side, at the bottom and at the bottom while subject is lying on his side. 3. The square is observed obliquely at a side. Drawing method and selection method were executed. Result for 1; critical distortion point is 4m. Result for 2 and 3; i. Perceptive image is little influenced by the figure's upside-down and subject's posture. ii. Generally the degree of constancy is slight as the observation distance is larger and the observation point's deflection angle is smaller. iii. Perceptive image is nearly the same as when fixation points exist. Result for 4; i. Perceptive image converges to horizontal direction, but there is little convergence to vertical direction, that is, perceptive images differ from figure's upside-down. ii. Perceptive image through drawing method is larger in height and smaller in bredth than through selection method. iii. Perceptive image is indifferent to there are fixation point.
