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[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

Not quite the same, but perhaps a related phenomenon:
At the Exploratorium in San Francisco, there's an exhibit that
shows (if I recall correctly) one or more rotating wire-frame models,
illuminated by two colored lamps, with a wide baseline between the
two lamps. The light from the lamps is cast onto a screen, causing two
colored shadows of the model(s) to appear on the screen. When the screen

is viewed with anaglyph-type glasses with two different color lenses,
a single "3-dimensional shadow" appears.

(To those who have been to the Exploratorium: did I describe it
correctly?)

I have been to the Exploratorium but do not recall this intriguing item.

As far as shadows and 3D goes,  mathematical theories state that the
first dimension is a point with no width or length.  The second
dimension has length and width but no depth (or height).  The third
dimension has length, width and depth (or height).
 Therefore the shadow of a three dimensional object is 2 dimensional (we
all know this).  In mathematics, the shadow of a four dimensional object
is three dimensional and, of course, the shadow of a two dimensional
object is one dimensional.  Put another way, the shadow of any object is
always one dimension less than the object itself.  Or n's shadow is
equal to (n minus 1).  Is this correct John B.?

Your example seems to be turning this theory on its head.

A longer description and illustration of the above can be found on my
site next to the Apparatus to View the Illusion of 4 Dimensionality
image.

Thanks for the example.

Dale Walsh

http://welcome.to/solidillusions




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