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"Ambiguous Objects" that change their appearances in a mirror
I found a class of objects that change the appearances when they are reflected in a mirror. Of course, the shape of an object should not change even if it is reflected in a mirror. So the change of the appearance is a kind of optical illusion.
This illusion is evoked by cylindrical surfaces.
The roof of a garage appears to be quite different in a mirror. Our brains seem to interpret the edge of the roof as the planar cut perpendicular to the axis of the roof.
A paper model of this roof can be made from the construction kit. This illusion won the 2nd prize of the Best Illusion of the Year Contest 2015.
Full Moon and Star
The section of this cylinder appears to be a full moon, while that in a mirror appears to be a star.
Wine Glass and Bottle
This cylinder appear to ba a wine glass if it is seen directly, while it appears to be a bottle in a mirror.
Flower and Butterfly
It appears to be a flower but it changes to a butterfly in a mirror. A general view of this object is shown in the right lower part.
Rotation of Gingko Leaf
The section of the cylinder apperars to be a gingko leaf. The shape does not change in a mirror, but it is rotation by 90 degrees. A general view of this object is shown in the right lower corner.
More Ambiguous Cylinders
"Ambiguous Garage Roof"
won the 2nd prize of the 11th Best Illusion of the Year Contest 2015.
Ambiguous Cylinder "Rectangles and Circles"
This illusion won the 2nd prize of the 12th Best Illusion of the Year Contest held in 2016.
3D printer data are here.
Large model (120width, 80depth, 54height)
3D printer data (large)
The model of this size was used for the contest, but it requires a large-scale 3D printer and the printing cost is not small.
Small model (60width, 40depth, 27height)
3D printer data (small)
This model is suitable to a small-scale 3D printer.
The object was designed so that the rectangles and the circles can be seen most clearly if it is viewed in the direction 45 degrees downward from mutually opposite two sides.
It is effective to place a plane mirror behind the object, because we can enjoy the two views simultaneously. However, this cannot be done by a vertical mirror, because the two view directions cannot be achieved by a single viewpoint.
The mirror should be set in such a way that it faces a little downward. So a mirror rotatable around a vertical axis is recommended in order to tune the orientation of the mirror so that the two view directions are achieved by a single viewpoint.
I hope you could enjoy the illusion.
Movies
Ambiguous Cylinders 1
Ambiguous Cylinders 2
Many examples and the underlying mathematics of the ambiguous cylinders are shown in the electric book:
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