4 October 2009 Same Colour Illusion

[bystander]

Is there a particular reason why the green cylinder is there (assuming it is green and not an illusion! ) as the illusion works without it.

To supply the shadow, without which there is no illusion. As to why it's green I suppose any non-grey scale color would work.

[DavidLeodis]

Is there a particular reason why the green cylinder is there (assuming it is green and not an illusion! ) as the illusion works without it.

To supply the shadow, without which there is no illusion. As to why it's green I suppose any non-grey scale color would work.

Thanks bystander. So the illusion will still work if the cylinder was removed but the faint shadow was retained. The illusion is excellent and just seems improbable at first, and even more, looks. Making a printout and cutting squares is the best way I find to be definitely sure they are the same shade. Illusions are so confusing. Well they are at least to me!

[neufer]

Is there a particular reason why the green cylinder is there (assuming it is green and not an illusion! ) as the illusion works without it.

To supply the shadow, without which there is no illusion. As to why it's green
I suppose any non-grey scale color would work.

• • Memorable quotes for _Chicago_ (2002)
  Billy Flynn (Richard Gere): Give 'em the old razzle dazzle. Razzle razzle 'em.
  Give 'em an act with lots of flash in it and the reaction will be passionate.

<<Dazzle camouflage, also known as Razzle Dazzle or Dazzle painting, was a camouflage paint scheme used on ships, extensively during World War I and to a lesser extent in World War II. In a 1919 lecture, artist Norman Wilkinson explained: "The primary object of this scheme was not so much to cause the enemy to miss his shot when actually in firing position, but to mislead him, when the ship was first sighted, as to the correct position to take up. [Dazzle was a] method to produce an effect by paint in such a way that all accepted forms of a ship are broken up by masses of strongly contrasted colour, consequently making it a matter of difficulty for a submarine to decide on the exact course of the vessel to be attacked.... The colours mostly in use were black, white, blue and green.... When making a design for a vessel, vertical lines were largely avoided. Sloping lines, curves and stripes are by far the best and give greater distortion."


HMAS Yarra in dazzle camouflage while sailing in the Persian Gulf – August 1941.

At first glance it seems unlikely camouflage, drawing attention to the ship rather than hiding it, but this technique was developed after the Allied Navy's failure to develop effective means to disguise ships in all weather. Dazzle did not conceal the ship but made it difficult for the enemy to estimate its speed and heading. The idea was to disrupt the visual rangefinders used for naval artillery. Its purpose was confusion rather than concealment. An observer would find it difficult to know exactly whether the stern or the bow is in view; and it would be equally difficult to estimate whether the observed vessel is moving towards or away from the observer's position.

The rangefinders were based on the co-incidence principle with an optical mechanism, operated by a human to compute the range. The operator adjusted the mechanism until two half-images of the target lined up in a complete picture. Dazzle was intended to make that hard because clashing patterns looked abnormal even when the two halves were aligned. This became more important when submarine periscopes included similar rangefinders. As an additional feature, the dazzle pattern usually included a false bow wave to make estimation of the ship's speed difficult.

All British patterns were different, first tested on small wooden models viewed through a periscope in a studio. Most of the model designs were painted by women from London's Royal Academy of Arts. A foreman then scaled up their designs for the real thing. Painters, however, were not alone in the project. Creative people including sculptors, abstract artists, and set designers designed camouflage.

American naval leadership thought dazzle effective. In 1918, the U.S. Navy adopted it, as one of several techniques. However effective the scheme was in World War I, it became less useful as rangefinders and especially aircraft became more advanced, and, by the time it was put to use again in World War II, radar further reduced its effectiveness. However, it may still have confounded submarines. Dazzle's effectiveness is not certain. The British Admiralty concluded it had no effect on submarine attacks, but proved to be a morale boost for crews. It also increased the morale of people not involved in fighting; hundreds of wonderfully coloured ships in dock was nothing ever seen before or since. Winston Churchill considered deception in war to be an indispensable "element of léger de main, an original and sinister touch, which leaves the enemy puzzled as well as beaten.">>

[Chris Peterson]

Thanks bystander. So the illusion will still work if the cylinder was removed but the faint shadow was retained.

But it won't work as well, and for some people it won't work at all. The brain needs to interpret the darker area as a shadow. Without something visible to cast it, the dark area may not be interpreted as shadow, and the illusion can be spoiled.

[neufer]

Thanks bystander. So the illusion will still work if the cylinder was removed but the faint shadow was retained.

But it won't work as well, and for some people it won't work at all. The brain needs to interpret the darker area as a shadow.
Without something visible to cast it, the dark area may not be interpreted as shadow, and the illusion can be spoiled.

"Now wait a minute! I see something on top of the cylinder. No, it's nothing but a shadow. Now the troops are on the edge of the Wilmuth farm. Seven thousand armed men closing in on an old metal tube. Wait, that wasn't a shadow! It's something moving . . . solid metal . . . kind of shieldlike affair rising up out of the cylinder . . . It's going higher and higher. Why, it's standing on legs . . . actually rearing up on a sort of metal framework. Now it's reaching above the trees and the searchlights are on it. Hold on!"

[DavidLeodis]

Thanks bystander. So the illusion will still work if the cylinder was removed but the faint shadow was retained.

But it won't work as well, and for some people it won't work at all. The brain needs to interpret the darker area as a shadow.
Without something visible to cast it, the dark area may not be interpreted as shadow, and the illusion can be spoiled.

"Now wait a minute! I see something on top of the cylinder. No, it's nothing but a shadow. Now the troops are on the edge of the Wilmuth farm. Seven thousand armed men closing in on an old metal tube. Wait, that wasn't a shadow! It's something moving . . . solid metal . . . kind of shieldlike affair rising up out of the cylinder . . . It's going higher and higher. Why, it's standing on legs . . . actually rearing up on a sort of metal framework. Now it's reaching above the trees and the searchlights are on it. Hold on!"

Clever neufer. I'm beginning to understand the illusion now! The cylinder is actually a little green man from Mars. Quick, we need Tom Cruise.

[Carl Horn]

G'day, David, It's my understanding that something had to cast a shadow so that square B would actually be darker, although our mind's eye would see it as remaining 'white', so why not a green cylinder? Would you have preferred a blue cube? Cheers, Carl (PS I'm glad I started this thread - some interesting, educational, and entertaining comments).

[Carl Horn]

Seems I answered the post at the bottom of page 1 without realising there were already several postings on page 2.

[NoelC]

Art is illusion, illusion is Art.



-Noel

[jerbil]

I truly enjoyed the spelling exposition on the use of the "u" in vario(u)s words in the English language. As a Brit I tend to object to some substitions of "f" instead of "ph", for example in the word "sulfur." On the other hand, with the huge contribution to American culture of the Spanish influence, in which the "f" is obligatory, it is understandable.

Quite apart from these etymological discussions, I am amazed that pregnancy has come into the discussion, and I am a male. What a "fertile" thread this has become!

[Redbone]

Audio illusions as well:

http://www.uwec.edu/walkerjs/PicturesOf ... _tones.wav

http://www.uwec.edu/walkerjs/PicturesOf ... bient).wav

[haemodomru]

i played this puzzle to compare A and B
http://www.puzzcore.com/game/091007SJ5T

[neufer]

I truly enjoyed the spelling exposition on the use of the "u" in vario(u)s words in the English language. As a Brit I tend to object to some substitions of "f" instead of "ph", for example in the word "sulfur." On the other hand, with the huge contribution to American culture of the Spanish influence, in which the "f" is obligatory, it is understandable.

Quite apart from these etymological discussions, I am amazed that pregnancy has come into the discussion, and I am a male.

Then it's probably OK phor you to phollow Rob's procedure:

Head sideways, cross eyes, move square A over square B, and run them around a little so there's a bit of overlap.

[geckzilla]

I spelled sulfur as "sulphur" on my chemical spelling test in high school chemistry class and the teacher counted it wrong. It marred my perfect score.

[Chris Peterson]

I spelled sulfur as "sulphur" on my chemical spelling test in high school chemistry class and the teacher counted it wrong. It marred my perfect score. :cry:

"Sulfur" is certainly the preferred spelling in the U.S., but "sulphur" is an acceptable spelling. That was a bad teacher you had- all the more since penalizing for spelling on a chemistry exam isn't very reasonable.

[geckzilla]

It was on the same test making sure we knew the chemical symbols. The symbol was listed and then we had to write in the name of the element. The instructions did state and she made sure we knew that we would be graded on our spelling. I didn't mind but was pretty burned by that 1 point shy of perfection.

Man, all I have are bad memories from that class. I remember she was teaching us about hydrogen and mentioned tritium being radioactive so of course I put two and two together in my mind and blurted out the question, "Is that what they use to make hydrogen bombs?" and everyone looked at me like I had just asked the most inappropriate question ever, like I wanted to build one and blow everyone up or something. I really enjoy science but my peers and the teacher made my chemistry class unbearable.

[bystander]

Art is illusion, illusion is Art.

We have it on good authority, Art is just an illusion, feel free to ignore him.