T3D Re: From Euclid to Wheatstone

[abram klooswyk <abram.klooswyk@xxxxxx>]

As a reaction on my statement in t3d 367:
>But there is no record of awareness of binocular depth perception
>before Leonardo da Vinci (...) 

Jim Crowell wrote (same TECH-3D Digest 367, 26 Sep 1998)
>Actually, I don't think that's correct.  The Egyptian mathematician 
>AlHazen seems to have known a fair amount about it, & I'm pretty sure 
>he predated da Vinci.  I believe there's a collection of his writings 
>out now, edited by Ian Howard of York University...

The short answer would be: please show me AlHazen's stereodrawings.:-)

I didn't think subscribers to the list would be in favour of filling up
a
digest with literature references, so I did omit them. Moreover,
although I have read Euclid's Optics (most of it in translation), I have 
read only portions, or even only quotations, of Aristotle, Ptolemy,
Galen, 
Alhazen, Alkindi, Aguilonius, Della Porta, Descartes, Berkeley.

So I have to rely on secondary literature. 
I would especially recommend to all interested in the subject (if there 
is anyone left in the audience :-)) to read:
Nicolas J. Wade: "On the late invention of the stereoscope", Perception
1987, vol 16 pages 785-818. 
Wade says in his abstract: "It was not until 1838, when Wheatstone 
published his account of the stereoscope, that stereoscopic depth 
perception entered into the body of binocular phenomena." 
[Wade goes on to mention several other facts of binocular vision that 
indeed were described earlier]

Since then Ian P Howard has published: "Alhazen's neglected discoveries
of visual phenomena", Perception 1996, vol 25, pages 1203-1217, and
at the same time Ian P Howard and Nicholas J Wade together have
published:
"Ptolemy's contributions to the geometry of binocular vision",
Perception
1996, vol 25 pages 1189-1201. (So on the pages preceding the article by
Howard alone).
In the latter article (by both authors) is said:
"Ptolemy also failed to see the connection between double images and
the perception of depth. That development had to wait for Wheatstone in
1838", and they refer to Wade's 1987 article.

So it seems that, although more has become known about Alhazen, Howard
and Wade still think that the first to give an adequately description of
binocular depth perception was Wheatstone. I believe Wade is at present
among the foremost authorities on the history of binocular depth
perception.

When reading Joseph Harris' observations, and especially those by 
Robert Smith, I found it tantalising to see how near they came to the 
discovery of stereoscopy and stereo imaging.
Robert Smith in 1738, exactly 100 years before Wheatstone, did several
fusion experiments, some of them new. 
He has drawn two crossing lines on a "plane board", and obviously the 
distance separating them (at the edge of the board)  was equal to his 
interpupillary, "... and a pin be stuck upright at their intersection f, 
and the pupils of the eyes be placed near the edge of the board (...), 
while the pin is viewed steadily, the two lines fa fb will appear united 
and upright in the place or by the side of the pin".

Reading this I can't help thinking: now go on, make a stereodrawing!
It strongly reminds me of my children's efforts in reading. 
On a certain day a child has learned several individual characters. 
Than a typical conversation could be: 
F: which characters you read? Ch: d, o, g.  F: Right! so now what is 
the word? Ch: d - o - g ... bog! F: excellent! almost good! try again.
Ch: d - o -g .... dock!  F: you nearly had it! one more try, listen to 
the sound dddd-ooooo-ggggg. Ch: ddd-ooo-ggg... doll!
This no-fusion phase could take several days or weeks, and it's complete 
useless for a parent to say the right word.

The phase in science between the understanding of all kinds of binocular
phenomena and understanding of stereoscopy took over 2000 years. 
There must have been some unsurmountable threshold, related to the phase 
of development of the culture in general.
I have said elsewhere that stereoscopy could not have been invented
before the world discovered man as an individual.
So not before Rousseau wrote "Emile" (1762), or before human rights
were declared by the American Congress (1776) and the French Assemble
Nationale (1789), not before Lavoisier, Galvani and Mueller started
modern physiology, or before the invention of the stethoscope (1816).

Wade explains the Late Invention by technical factors in the science
of vision, and he apparently sees Wheatstone's observation as
accidental.
This might be right, but in my opinion there's more to it.

Abram Klooswyk


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