Re: [photo-3d] Re: do you believe it?

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

Yes, stereoscopic vision does require two different images.   The brain
compares difference information and interprets this as depth.

However, there are many ways of encoding difference information in a
picture.

This can be true stereoscopic as with an anaglyph or a Pulfrich (or other
time parallax type image), or it can be "false 3D", which are simply images
that give the impression of depth, buf the depth is not encoded in a manner
such that it simulates the actual depth relationships of the original scene.
An example is the chromatic systems, such as the one that involves
diffraction grating grids that spread light in proportion to wavelength,
yielding a wavelength, or color hue differentiation (ChromaDepth).

Although I have not had time to check out the pinhole method, I would guess
that this is a related effect.

Since a very small aperture increases depth of field, these would allow
image information to be resolved on the rods in the retina, where this
information is normally too diffuse to be interpreted as sharp image
elements.

If the monochrome image information, which is displaced from the
trichromatic (received by the cones), it is likely that this will also
result in chromatic difference information that the brain interprets as
depth.

Although this would be classified as "false 3D" like other depth signals
that are not keyed by real depth information in the subject, the results (as
with ChromaDepth) under the right circumstances can appear quite convincing.

The reason for this is a rather convenient visual coincidence involving a
common monoscopic depth cue.  In many (but not all) situations in real life,
warm colored subjects (people, red, orange, yellow, tan, gold, etc. colored
objects) just happen to be in the foreground, while cool colored backgrounds
(grass, trees, sky, distant mountains, etc.) are farther away.  This can
give a sometimes rather convincing appearance to chromatic differentiation
systems.

Of course, this can also backfire and produce rather wierd, sometimes even
amusing, false depth effects when the colors are not arranged in a logical
sequence for the effect.  An example would be a person in a red shirt with
blue slacks.  The top half of their body would appear to float out in front
of the bottom half.  Actually, it might work with Dolly Parton...

JR

----- Original Message -----
From: "Herbert C Maxey" <bmaxey1@xxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Sunday, October 15, 2000 1:09 PM
Subject: Re: [photo-3d] Re: do you believe it?


> >>>Make any picture 3-D using only your fingers.
>
> By happenstance, I was thumbing through the current "Discover" Magazine;
> at least I think it was that one, and I came across a few example of
> colored circles. The short filler was about seeing "False 3D". I am not
> an expert, but since there is an apparent thing called False 3D, perhaps
> the above might also fool the brain. The brain can be fooled in many way,
> as can hearing.
>
> You can't make any picture 3D (Stereoscopic). There is no possible way.
> What is being demonstrated is some other visual artifact. Stereoscopic
> Vision requires 2 different views.
>
> Bob
>
>
>
>