Re: What can you do in 2d that cannot do in 3d

[P3D KENNETH LUKER <KLUKER@xxxxxxxxxxxxxxxxxxxxxxx>]

I may have found an example of what can be done in 2d and not in 3d.
Remember the M. C. Escher graphics that include an impossibly-shaped
connection of three rectangular-cross-sectioned bars?  An extension
of the principle is used to make the Escher cube--an impossible
open-box made of plane-faced struts.  The faces of the sides of the
bars are arranged in a way that is impossible in real space. 

One can construct a model that consists of bars joined in such a way
that, when viewed with ONE EYE from precisely the correct position,
the construction looks exactly like the Escher fixture.  You may
have seen a photograph of such a model--it works, but ONLY IN 2D!  If
one were to take a 3d picture of that model, the trompe l'oeil effect
would disappear and the structure would be revealed as a fake.

I believe one cannot, in principle, make a convincing 3d photograph of
the Escher fixture.

  (I can't even make an ascii drawing of one!)
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Ken Luker_______________________________________________________________
Kenneth Luker
Marriott Library Systems and Technical Services
KLUKER@xxxxxxxxxxxxxxxx


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