Re: PHOTO-3D digest 1355

[P3D Neil Harrington <nharrington@xxxxxxxxxxxxx>]

William Carter writes:

>I will agree that Wheatstone may have been the first to make drawings in 
>3-D (His first appeared in 1838). But, the argument that "One could not 
>have a better "proof" or demonstration of stereopsis" does not apply. I 
>think the 1677 invention of a stereo microscope is a far more palpable 
>demonstration of proof. 

Maybe I missed something, but the original mention of this 1677 microscope
described it, I thought, as a BINOCULAR microscope.  Is there any real
evidence that the inventor had stereo microscopy in mind when he designed
it?  I don't pretend to have an expert knowledge of microscopes, but I
believe the modern dual-eyepiece, single-objective microscopes are not 3-D
instruments at all, but simply present the same image (via a beamsplitter,
presumably) to both eyes, the object being to allow the microscopist the
greater comfort of using both eyes rather than one.  Isn't it possible that
that 17th-century designer had some similar purpose in mind?  Without some
clear evidence of his intent, I wouldn't jump to the conclusion that he
understood stereopsis just because he had the idea of making a dual microscope.

Also, the earlier post mentioned this instrument being shown in an engraving
in a book.  Is there any evidence that it actually existed?  Obviously it's
a lot easier to make a drawing of a microscope than to manufacture a microscope.

>Further, Wheatstone knew about this stereo 
>microscope, for he described it in 'Transactions of the Microscopal 
>Society' (1853, I, 99-102).

Did he actually describe it AS a "stereo microscope"?  

It seems to me it would be awfully hard to make a real 3-D microscope with
17th-century technology, chiefly because of the difficulty (if not
impossibility) of getting the objective lenses close enough together for
that purpose--unless we are talking about a VERY low-powered microscope.

>The reasoning behind my assertion that, by considering spheres and round 
>columns, Leonardo and Euclid have proven to me they fully grasped the 
>conciept of stereopsis, is that I don't consider cardboarded edge 
>boundary recognition to be a cogent Z-axis construct. I don't think that 
>any dual lens stereo system can render a realistic stereo picture. They 
>are flawed in their ability to record a continuous form. 

But of course that's a limitation shared by photographs of any other kind.
All pictures have borders of some sort.  It doesn't seem very important to
me, since the perception of 3-D seems to be pretty much limited to the
central part of one's vision anyway.  Am I missing something here?



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