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Comments on Lecture 18 "Ambiguety with Shadows"

Comment 1. Answer to the question"

As shown in the first image, the shadow cast by the back light generates an upside-down shape of the bat on the desk surface. The question was "Is it possible to create the shadow in a normal posture?"

We can create the bat in a normal posture by placing the light below and cast the shadow on a vertical wall behind the object, as shown in the second image.


Comment 2. References of the objects used in the lecture

In this lecture we used the ambiguous objects, the deformable objects, and the reflexively-fused ambiguous objects. The following are references on those objects, although the representation using shadows is not referred to.

[Amgibuous Objects]
K. Sugihara: Ambiguous cylinders: A new class of impossible objects. Computer Aided Drafting, Design and manufacturing, vol. 25, no. 3 (2015), pp. 19--25.
[Deformable Objects]
K. Sugihara: Anomalous Mirror Symmetry Generated by Optical Illusion. Symmetry, vol. 8, no. 4 (2016), p. 21, doi:10.3390/sym8040021 (http://www.mdpi.com/2073-8994/8/4/21)
[Reflexively-fused ambiguous objects]
K. Sugihara and M. Moriguchi: Reflexively-Fused Cylinders. Symmetry, vol. 10, no. 7 (2018), p. 275