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From: hughes, b 
Subject: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 16:34:06
Message: <3d9763be@news.povray.org>
Someone posted this illusion at a camera board and so I just had to try 
it using POV-Ray. I don't know what the other was made with, the person 
didn't say where they got it from.

I found that I couldn't get perfect uniformity when using radiosity but 
without it the render didn't look good. It's close enough to get the 
effect. To check against your sense of vision you'll need to either cut 
and paste parts together or use a color picking eyedropper thing which 
many paint programs have and compare values.

Hope it looks as good to you as I thought it was. Couple hours to make, 
30 minutes for final render.


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Attachments:
Download 'illusion_checkers.jpg' (31 KB)

Preview of image 'illusion_checkers.jpg'
illusion_checkers.jpg


 

From: Ken
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 16:40:16
Message: <3D9764FE.749AF3F1@pacbell.net>
"hughes, b." wrote:
> 
> Someone posted this illusion at a camera board and so I just had to try
> it using POV-Ray.

> Hope it looks as good to you as I thought it was. Couple hours to make,
> 30 minutes for final render.

I don't get it. What illusion?

-- 
Ken Tyler


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From: IMBJR
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 16:50:02
Message: <m8oepugd69qojmsg6gjp50353bqvvq0sbq@4ax.com>
On Sun, 29 Sep 2002 15:33:10 -0500, "hughes, b."
<omn### [at] charternet> wrote:

>Someone posted this illusion at a camera board and so I just had to try 
>it using POV-Ray. I don't know what the other was made with, the person 
>didn't say where they got it from.
>
>I found that I couldn't get perfect uniformity when using radiosity but 
>without it the render didn't look good. It's close enough to get the 
>effect. To check against your sense of vision you'll need to either cut 
>and paste parts together or use a color picking eyedropper thing which 
>many paint programs have and compare values.
>
>Hope it looks as good to you as I thought it was. Couple hours to make, 
>30 minutes for final render.

Mmm, I saw this elsewhere recently and just simply refused to believe
it was an illusion - until I got the eyedropper out ... damn that's
odd.

--------------------
http://www.imbjr.com


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From: St 
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 16:59:54
Message: <3d9769ca@news.povray.org>
"Ken" <tyl### [at] pacbellnet> wrote in message
news:3D9764FE.749AF3F1@pacbell.net...

> I don't get it. What illusion?

 IIRC Ken, square A is supposed to be the same shade of grey as square
B, even though they look different, (so I agree, where's the illusion?)

  Hope I'm right with this!  :oP

    ~Steve~




>
> --
> Ken Tyler


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From: Christoph Hormann
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 17:00:50
Message: <3D976A02.95E9626B@gmx.de>
"hughes, b." wrote:
> 
> Someone posted this illusion at a camera board and so I just had to try
> it using POV-Ray. I don't know what the other was made with, the person
> didn't say where they got it from.
> 

http://almstrom.org/illusion.jpg

Your's is looking much better of course.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Gilles Tran
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 17:45:31
Message: <3d97747b@news.povray.org>

3d9763be@news.povray.org...
> Someone posted this illusion at a camera board and so I just had to try
> it using POV-Ray. I don't know what the other was made with, the person
> didn't say where they got it from.

Must be a recent craze, I came upon this a couple of days ago.
http://www-bcs.mit.edu/gaz/gaz-teaching/index.html
I'm not sure I've understood all the explanations, but it's certainly
interesting.

I fell for it recently in one of my own images too. I was trying to touch-up
some parts of an image and the eyedropper was in clear contradiction with my
eyes, so I kept smudging what I thought was a dark blue and it didn't match.
The eyedropper was right of course...

G.


--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: JPGargoyle
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 18:34:14
Message: <3d977fe6@news.povray.org>
And a friend sent me this one with the comparison.
Pretty interesting. My eyes still refuse to accept it he he he :)

Best regards.



> http://almstrom.org/illusion.jpg
>
> Your's is looking much better of course.
>
> Christoph


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Attachments:
Download 'checkershadow-AB - Verified.jpg' (45 KB)

Preview of image 'checkershadow-AB - Verified.jpg'
checkershadow-AB - Verified.jpg


 

From: hughes, b 
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 18:34:49
Message: <3d978009@news.povray.org>
"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3D976A02.95E9626B@gmx.de...
>
> http://almstrom.org/illusion.jpg
>
> Your's is looking much better of course.

Oh of course, it's POV. Thanks anyway.

I didn't see the authors name printed onto the image before. Went back to
see again and there was a vertical scroll bar with just that bottom part
unseen. I could have 'net searched immediately using the name had I known
that.


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From: hughes, b 
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 18:35:27
Message: <3d97802f@news.povray.org>
"Gilles Tran" <git### [at] wanadoofr> wrote in message
news:3d97747b@news.povray.org...
>
> Must be a recent craze, I came upon this a couple of days ago.
> http://www-bcs.mit.edu/gaz/gaz-teaching/index.html
> I'm not sure I've understood all the explanations, but it's certainly
> interesting.
>
> I fell for it recently in one of my own images too. I was trying to
touch-up
> some parts of an image and the eyedropper was in clear contradiction with
my
> eyes, so I kept smudging what I thought was a dark blue and it didn't
match.
> The eyedropper was right of course...

Those are some other things to try, thanks.

Some interesting things I found just now, the Munker-White link shows colors
affected too, as you said. We trust our eyes way too much, now I'm going to
be thinking it over all the time when doing a render!
http://persci.mit.edu/gallery.html
--
Farewell,
Bob


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From: hughes, b 
Subject: Re: illusion checkers [~40KB Jpg]
Date: 29 Sep 2002 19:22:30
Message: <3d978b36$3@news.povray.org>
"JPGargoyle" <jot### [at] netcabopt> wrote in message
news:3d977fe6@news.povray.org...
> And a friend sent me this one with the comparison.
> Pretty interesting. My eyes still refuse to accept it he he he :)

That's obviously just a gradient with shades of gray there. ;-)


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