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From: Joel S Utz <jutz at>

Date: Tue, 26 Jun 2001 16:19:44 UTC


      Trigonometry tells me that, for the worst case (airplane 
perpendicular to line of sight at the top back corner of the box), 
the wing tip will shift less than one tenth of a receptor and the 
vertical stabilizer (assuming it's 3' tall) will shift by one half of 
one receptor. If the eye were strictly black and white (no grey 
levels at all) it would be incapable of detecting such a difference. 
Most people, however, can discern more than 10 levels of intensity of 
any given color and could detect that small a change.

>This question had led to some great research and innovative thinking.  But,
>how about figuring out what it takes to see a five degree misalignment on the
>roll axis of a 20 foot wingspan aircraft at the top of the back end of the
>box !  Trigonometry, which I have forgotten how to perform, would tell one
>how many inches of displacement of a wing tip would occur for each five
>degrees.  One could go on from there.  Being able to see the airplane is not
>the ultimate requirement of judging; it is the displacement from perfect that
>is the requirement.
>Dick Rihn

    I could correlate to an eye chart but, as I indicated in the last 
paragraph of my previous post, I'm pretty sure this is all just 
trivia and not really worth the effort of finding an eye chart. I 
really think the only productive action would be comparison of human 
grades against some verifiable, absolute standard.

    Since hallucinations are random, multiple judges and the averaging 
system should filter them out. If the majority of the judges 
hallucinated you out of a few points then you have to assume that it 
was mass hypnosis and some very powerful, secret society is out to 
get you.

                                                   Joel Samuel Utz
                                                   jutz at
                                                   joel.utz at (work)


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