Re: Pulfrich and Real vs. Artifial 3D

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

>Gabriel writes:
>
>>Well, respectfully I would have to disagree. I wondered about the 
>>reference about Pulfrich being an "illusion" and not being true 
>>stereoscopic 3D a while back. 
>
>To clarify things:  Pulfrich is stereoscopic.  Whether a person 
>chooses to call it "illusion" that's their choice.  I have heard 
>people (some of them into stereoscopic photography) call "true" 
>stereoscopic imaging an "illusion" (as opposed to "direct" 
>stereoscopic vision?)

Yes very true but the connotation they are suggesting (in the context
described) is that it is NOT stereoscopic but an illusion. I am very
well aware of what your saying but most references to Pulfrich 3D
is that it is a simulation IN REGARD to the other forms of 3D. This,
I stated in my last post but stating it more explicitly now, because
I think you overlooked that statement.

Yes I have heard true stereoscopic imaging an "illusion" compared to
direct stereoscopic vision, but lets compare apples to apples here.
I will repeat and rephrase the above to make it clear. How is 
Pulfrich 3D an illusion compared to the other stereoscopic imaging???
It's not a matter of choice in this regard.

>- "Real" stereo
>- "Artificial" stereo
>- "Virtual" stereo

I like your categorizing stereo but we differ in the views regarding
Pulfrich.

>By "artificial" stereo I am referring to situations where there is
>stereoscopic imaging but the depth seen is artificial, i.e., does
>not relate to variations in the 3d dimension in the real object.
>Examples of that are:  3-D pictures of comments or eclipse of the
>sun recorded from the same station, situations where only one
>object is being shifted in the scene during recording from same
>location.  One application in my research was visualizing plastic
>strains.  I treated two pictures taken during the deformation of
>a sample as a stereoscopic pair and was able to visualize the
>plastic deformation as a change in depth.  In this category I
>put Pulfrich too.

I agree with the above but don't categorize Pulfrich as artificial,
by your definition of artificial.

>By "virtual" stereo I am referring to situations where a real 
>object does not exist.  Examples:  Stereoscopic drawings (first
>application of stereoscopic imaging back in 1836 in Wheatstone's
>classic paper), computer 3d, etc.

>All these categories include "valid" true stereoscopic images and
>have applications in science and entertainment.  I personally
>would prefer to see the "real" than "artificial" stereo in TV
>when it is used in connection with real objects.  Someone called
>Pulfrich the "basement bargain" of 3D motion pictures and I tend
>to agree with the characterization.

With this logic I would take it to mean using one camera to capture
3D by shifting, to be artificial??? Of course not. So why is Pulfrich
artificial? The end result of Pulfrich, is true stereoscopic viewing.

As to "bargain basement" this is a matter of calling it whatever they
want and this is their choice, but it is still true 3D. I really don't see
how alot of people are confused by all this. The concept is rather simple.

Gabriel



------------------------------

End of PHOTO-3D Digest 2100
***************************
***************************
 Trouble? Send e-mail to 
 wier@xxxxxxxxxxxxxxx 
 To unsubscribe select one of the following,
 place it in the BODY of a message and send it to:
 listserv@xxxxxxxxxxxxxxx 
   unsubscribe photo-3d
   unsubscribe sell-3d
   unsubscribe mc68hc11
   unsubscribe overland-trails
   unsubscribe icom
 ***************************