P3D Re: Explanation of 3-DVG effect

[KenDunkley@xxxxxxx]

In a message dated 98-02-04 09:23:53 EST, you write:

<< But if you are unlucky enough to have strong red objects behind blue ones,
 the image will appear pseudo in those areas.
 
 Surprisingly, the effect is descernible in B+W photos as well, though not
 as strongly. With brighter objects appearing closer, I think.
 
 I propose that the effect is created by differential chromatic aberration
 caused by the glancing view through pinholes.  Red colors appear more (or
 less?) shifted than Blue,  >>

Boris 

You are perhaps the first person to raise issues that go 
beyond the obvious explanation   of differential chromatic 
aberration as a complete explanation for the 3-DVG 
effect.  You noticed that it works with b&w pictures 
(although much reduced). 

Frankly, you will find that it works (although very much 
reduced) with black and white line perspective 
drawings and also white lines on black background 
perspective drawings . It also  work surprising well
 with monochrome pictures in virtually any single 
color. Using the advanced version of the device 
(the unit illustrated in the StereoWorld article) 
make this assessment much easier. 

Also,  differential chromatic aberration only explains  
the shifting of colors relative to the plane of the 
drawing.  It in no way can explain how every element
 in the picture appears properly located in depth 
relative to every other element regardless of its color. 
In other words if you have two almost identical 
pictures, one with a red car in front of a blue truck 
and a second virtually picture with the colors transposed.  
You will find the (now) blue car still appears to be in 
front of the (now) red truck.  

Now, I challenge you and other list members to 
explain these results*. 

Good luck.

Best regards, Ken Dunkley

*I do need to clarify one point that I have make 
elsewhere: if at any time you position the pinholes 
such that any color pops off the page or the 
pictorial object associated with it, you have 
stretched the pinholes too far apart. To eliminate 
this one needs to reduce the overlap and or use 
smaller diameter pinholes. Generally speaking, 
most pictures will respond.  However, there are 
some pictures (about 1 in 15) that do not. Also, 
I need to inform you that there are some pictures
 (I have found about six of  them in total) that 
work only when the pinholes are moved in the
 opposite direction.


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