The study on “ITO EFFECT”

Abstract

In contour map plotting of cultural properties, such as artistic crafts and reliefs of Budda, an operator sometimes draws false contour lines at regular interval as if there exsist a nomal slope, although the proper stereoscopical view can not be obtained in fact.
In Nara National Cultural Properties Research Institute, we call this phenomenon “Ito Effect” after it's finder.
“Ito Effect” occurs where the plotting is essentially impossible, but every operator draws false contour lines unconsciously. This operator's action may be caused by mental process that is called psychologically the shape constancy or shape complement.
As “Ito Effect” is affected by the camera position, tones and contrasts of pictures and so on, we can check this phenomenon by taking photograpies with careful consideration for these conditions.