INFORMATION

This website uses cookies to store information on your computer. Some of these cookies are essential to make our site work and others help us to improve by giving us some insight into how the site is being used. For further information, see our Privacy Policy. Continuing to use this website is acceptance of these cookies.

3-D Optical Illusions

Any topic related to science can be discussed here.
Message
Author
User avatar
Emma Woolgatherer
Posts: 2976
Joined: February 27th, 2008, 12:17 pm

Re: 3-D Optical Illusions

#21 Postby Emma Woolgatherer » July 2nd, 2009, 12:32 am

Latest post of the previous page:

Alan H wrote:The 'green' and the 'blue' are, in fact, the same colour!

For further details, see Richard Wiseman's blog.

Not that I didn't believe him, but I've checked it as well!
See the response from "Carl":
That’s pretty impressive, although there is a bit of a digital-image artefact which could be affecting the result. If you zoom in a lot so you can see the individual pixels, you’ll notice that the jaggy borders between colour regions have significant ‘anti-aliasing’, resulting in several pixels of an in-between colour along the borders. This is a standard digital image technique, making jaggy, pixelated lines look smoother. However, in this case, it could be accused of contributing to the perceived illusion effect.

You’ll note that at the centre of the image, the spirals get so close together that the anti-aliased blends become larger than the spirals themselves, and so most of the pixels of the ‘green’ are very much NOT the same colour as the pixels of the ‘blue’.

However, I will concede that the bands at the outside are wide enough so that there is significant amounts of same-coloured pixels. So, yeah, after all that, it seems the illusion still ‘works’, and it’s damned good.

Still, for complete rigour, I wonder if anyone can be bothered rendering a high-resolution version with no anti-aliasing.
This version has no anti-aliasing, and although it still works as an optical illusion, it's easier to see that the 'blue' and the 'green' are actually the same colour:

Image

Emma

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#22 Postby Alan H » July 2nd, 2009, 1:16 am

Thanks for pointing that out Emma. I did notice some artefacts in the image in PaintShop Pro when I was messing with it, but they seemed fairly minor. (I wonder if it was ever compressed as a jpeg at sometime in its life?) The version you give is clearer. Still fascinating!
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
Paolo
Posts: 1474
Joined: September 13th, 2008, 9:15 am

Re: 3-D Optical Illusions

#23 Postby Paolo » July 4th, 2009, 12:48 pm

The perceived difference in colour is due to the variation in the colour of the bands passing through (pink or orange). I expect the effect only works at smallish scales, because I am guessing that the eye is averaging the colours somewhat as they are banded - there is a limited density of colour detecting cones in our eye and the signals they transmit are boosted before reaching the brain, so small errors in colour perception acuity are magnified considerably.

There is an interesting "making of" section in the Fight Club dvd, where they discuss the difficulties of creating a scene where furniture in a room is added and altered in the style of an Ikea catalogue. Apparently it was the most difficult scene to film because the effect of adding one object to the shot completely altered the colour perceived by the viewer. As a result they had to constantly adjust the lighting the reduce this contextualising of tone that made it appear as though the colour of the walls was constantly changing.

I have altered the version that Emma posted so that the green lines are adjacent to each other, so the difference between the visual context of pink and orange lines is more apparent - note how the effect is maintained when you look at the picture as a whole, but is lost when you focus on the centre of the image where the pink and orange lines meet.
illusion-test1.jpg
illusion-test1.jpg (62.54 KiB) Viewed 2928 times

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#24 Postby Alan H » September 16th, 2009, 10:51 am

Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
jaywhat
Posts: 15807
Joined: July 5th, 2007, 5:53 pm

Re: 3-D Optical Illusions

#25 Postby jaywhat » September 16th, 2009, 11:56 am


User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#26 Postby Alan H » September 16th, 2009, 2:26 pm

Oops!
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
jaywhat
Posts: 15807
Joined: July 5th, 2007, 5:53 pm

Re: 3-D Optical Illusions

#27 Postby jaywhat » September 16th, 2009, 4:52 pm

I think you need 2 good and/or equal eyes to see circles. I can't.

User avatar
Alan C.
Posts: 10356
Joined: July 4th, 2007, 3:35 pm

Re: 3-D Optical Illusions

#28 Postby Alan C. » September 16th, 2009, 6:06 pm

jaywhat wrote:I think you need 2 good and/or equal eyes to see circles. I can't.

There are very few optical illusions that work for me, I certainly could not see any circles.
Abstinence Makes the Church Grow Fondlers.

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#29 Postby Alan H » September 17th, 2009, 1:25 am

The circles are caused by the two mitres at the bottom of one panel and the top two of the panel below. They don't look as if they would create circles but they form vivid ones! Does that help?
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
jaywhat
Posts: 15807
Joined: July 5th, 2007, 5:53 pm

Re: 3-D Optical Illusions

#30 Postby jaywhat » September 17th, 2009, 6:13 am

Alan H wrote:The circles are caused by the two mitres at the bottom of one panel and the top two of the panel below. They don't look as if they would create circles but they form vivid ones! Does that help?



No, but I would be interested to know if anyone can see the circles with one eye closed. You see, I believe this is sterescopy which needs two eyes to work.

User avatar
Fia
Posts: 5480
Joined: July 6th, 2007, 8:29 pm

Re: 3-D Optical Illusions

#31 Postby Fia » September 17th, 2009, 11:12 am

Hmmm, I can see no circles with both eyes or right eye only, but loads of them with my left eye... though the ones in the middle rows came and went...

User avatar
jaywhat
Posts: 15807
Joined: July 5th, 2007, 5:53 pm

Re: 3-D Optical Illusions

#32 Postby jaywhat » September 17th, 2009, 11:33 am

jaywhat wrote: I believe this is sterescopy which needs two eyes to work.


Of course, I meant 'stereoscopy' - but I am surprised you can do it with one eye, Fia.
I must try again. Ninny says one has to really relax.....

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#33 Postby Alan H » September 17th, 2009, 1:33 pm

Although a bit more difficult, I can see it with just one eye. The circles enclose all the horizontal lines.
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
Alan C.
Posts: 10356
Joined: July 4th, 2007, 3:35 pm

Re: 3-D Optical Illusions

#34 Postby Alan C. » September 17th, 2009, 4:33 pm

Fia
Hmmm, I can see no circles with both eyes or right eye only, but loads of them with my left eye.
I just had another go and still can't see them but I have no sight in my left eye................Spooky :puzzled:
Abstinence Makes the Church Grow Fondlers.

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#35 Postby Alan H » September 20th, 2009, 11:58 pm

Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
Alan C.
Posts: 10356
Joined: July 4th, 2007, 3:35 pm

Re: 3-D Optical Illusions

#36 Postby Alan C. » September 21st, 2009, 6:25 pm

That one works for me, first I tried it looking at the dot and saw the rainbow, then I played it again without staring at the dot and the rainbow was black and white.
Abstinence Makes the Church Grow Fondlers.

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#37 Postby Alan H » June 13th, 2010, 11:13 pm

Somewhere between 2-D and 3-D!

YouTube - Crazy Tables Illusion
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
Dave B
Posts: 17809
Joined: May 17th, 2010, 9:15 pm

Re: 3-D Optical Illusions

#38 Postby Dave B » June 14th, 2010, 10:07 am

Fascinating stuff, especially since there is a difference in how some see the images. Since I joined late can I go back to the first one please?

The images are not identical, the right hand one has been shifted slightly to the left, there is more of the far figure shown and less of the wall. That alone could be enough to throw the eye off I think.

But I could not see any other difference between the images. With the towers I only noticed the apparent difference in angle when I was told what to expect. How much did suggestion come into that?

How much of it is due to experience, where the brain becomes experienced in certain kinds of problems? I was a Jack-of-all-trades technician in an instrumentation company R&D lab. Objective observation and analysis was part of my job, I needed to see what was there, not what I thought was there. So I might, literally, look at such things in a different way than others with no technical experience.

It would be interesting to try this on people from all walks of life and job types and see what results.
"Look forward; yesterday was a lesson, if you did not learn from it you wasted it."
Me, 2015

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#39 Postby Alan H » June 14th, 2010, 3:46 pm

Dave B wrote:The images are not identical, the right hand one has been shifted slightly to the left, there is more of the far figure shown and less of the wall. That alone could be enough to throw the eye off I think.
Hmmm...you're right. There are few pixels of difference down the left side, but it doesn't seem likely that that causes such a dramatic effect in the direction of the railway lines. If you think it does, I'll re-create the double picture by copying one and duplicating it so they are definitely identical.
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
Dave B
Posts: 17809
Joined: May 17th, 2010, 9:15 pm

Re: 3-D Optical Illusions

#40 Postby Dave B » June 14th, 2010, 4:06 pm

Alan H wrote:
Dave B wrote:The images are not identical, the right hand one has been shifted slightly to the left, there is more of the far figure shown and less of the wall. That alone could be enough to throw the eye off I think.
Hmmm...you're right. There are few pixels of difference down the left side, but it doesn't seem likely that that causes such a dramatic effect in the direction of the railway lines. If you think it does, I'll re-create the double picture by copying one and duplicating it so they are definitely identical.
Give it a go, Alan, I will be interested to see if it makes any difference to anyone.

I still cannot see any difference in angle. I was wondering whether or not the slight shift might make them something like a stereoscopic pair. Then there would be a discernible difference in the angle between one eye and the other in certain conditions, similar to the parallax shift you get when you close each eye in turn when looking at any 3D scene.

If the brain, presented with two images like that, tries to see them as a stereoscopic pair, in it would expect one of them to be viewed from a slightly different angle to the other, thus the geometry would be different. It's that old adage that we never see what is actually there, only what our brain "wants" or "expects" to see.
"Look forward; yesterday was a lesson, if you did not learn from it you wasted it."
Me, 2015

User avatar
Alan H
Posts: 24017
Joined: July 3rd, 2007, 10:26 pm

Re: 3-D Optical Illusions

#41 Postby Alan H » June 14th, 2010, 6:18 pm

I deleted the right one and pasted a copy of the left one to the right — they are both identical:
Rail illusion.png
Rail illusion.png (112.93 KiB) Viewed 4409 times
I still very clearly see the illusion of both sets of rails going off in different directions.
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?


Return to “Sciences and pseudo-science”

Who is online

Users browsing this forum: No registered users and 6 guests