Ambiguities
in 3-D patterns induced by lighting assumptions
Papathomas
T.V. &
A bistable pattern presented under its
four 90° rotations. The white and black, horizontal and vertical bars produce
an impression of slabs stacked up in depth either away (a) or toward (b) the
observer. It is postulated that these precepts are induced by the observer's
assumption on the location of the light source. When rotated as in (c) and in
(d), the arrangements of the white and black bars in the top and bottom parts
of each panel obey opposite lighting assumptions hence inducing
opposite/conflicting bistable precepts in each half.