> spinning 3D displays

The main reason these dropped out was the scan rate, and few other
reasons. Even the helix has troubles keeping up. It needs to do 3000 rpm
to stay invisible and the scan and video frequencies of the projecting TV
are all multiplied 50 times. Even leaving out the scan proper, and the
required luminous intensity (in theory 50 times larger == 3000W CRT
instead of 60W as is normal for a 19" CRT), a video (pixel) frequency of
50*14 MHz = 520MHz, a frame buffer of 50 times whatever your current frame
buffer size is (like say, 512MB ?), a spinning mass of probably 20 pounds
on a diameter of almost 2*19" at 3000 rpm may have enough gyroscopic
momentum to flip the cabinet over with the rotation of the earth <g>. Any
way the volume usage of the cabinet would be 33% at most (the rest is
taken by the part of the helix cylinder you are not supposed to see). Oh
and I forgot the noise, bearing life, and the electricity bill, plus some
shekels for software that generates 3D and some more to maintain and
expand those programs.

As you see, it's all very easy, but I remember the protoype was very small
(5 inches radius and 5" monitor afair).

Peter

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