I added some more to my added comment in the first post.
I will post below what I have added to the first post.
The above was for Mr.Orman to discuss the making of 3D with Mr.Bloggs, but sofar nobody has wanted to talk to him about making 3D, until now when I read Walter Murch talk about 3D: link
So after reading Walters letter to Roger Ebert I sat down and wrote the following below (I hope Mr.Orman doesn't get upset that somebody else's ideas are presented here besides his own):
3D is the perception of real distance when looking at the screen, 2D accomplished this.
"Once the x- and y-axis are specified, they determine the line along which the z-axis should lie" - wikipedia, Cartesian coordinate system.
This means once you've established the 2D x and y coordinates the z axis may exist.
2D video x and y axis brings a perception that the z axis exists, and this affiliation is seen even though there is only x and y axis.
When you see the z axis but it removes you from the story's immersion, it's because it's showing that the z axis is seen.
Test to show you 3D.
1.) Hold two fingers in front of your left or right eye and form a plus sign +, now you see how to hold your left and right hands, thumbs facing your face, in front of your left or right eye. Remember to keep both eyes open even though your holding your hands in front of only one eye.
2.) Open your computer and Notepad, make notepad full screen and then look at the white screen made by Notepad with your hands in a plus sign +, as described in step one.
3.) Now to see the 3D effect poke your thumb out towards your eye, so the thumb is pointing right in front of your eye, this is the z axis.
Now try without your thumb pointing in front of your eye, this is the x and y axis.
If your trying to see what's going on in Notepad, when your thumb pokes out it takes your attention away from the Notepad screen, doesn't it?
Presbyopia: is a age related eye disorder. What Presbyopia does to the eyes is it progressively diminishes the eyes ability to focus on near objects.
The problem of 3D TV, is that the audience must focus accommodation their eyes at the plane of the screen -- say it is 80 feet away. This is constant no matter what.
But their eyes must converge at perhaps 10 feet away, then 60 feet, then 120 feet, and so on, depending on what the illusion is.
Most people over the age of 50 lose the ability to link convergence and accommodation cues, due to Presbyopia.
All living things with eyes have always focussed and converged at the same point.
When the convergence changes, the eyes focus there. With Presbyopia the convergence changes, the convergence will be further in, but the focus cannot follow it.
This makes the mind concentrate on the convergence and not on the focus.
How this fits into films is if the mind concentrates on convergence and not focus the person identifies the video as 3D, or immersive, but if the mind focuses on the convergence and focus at the same time then there is zero parallax and so no 3D effect or immersion from positive and negative parallax.
The young eyes can see convergence and focus at close range, but the old eyes cannot because of Presbyopia, so the old eyes have the effect that 3D offers, and not 2D.
The Brechtian trick described by Walter Murch.
"Brecht created an influential theory of theatre, the epic theatre, wherein a play should not cause the spectator to emotionally identify with the action before
him or her, but should instead provoke rational self-reflection and a critical view of the actions on the stage.
For this purpose, Brecht employed the use of techniques that remind the spectator that the play is a representation of reality and not reality itself [...]. Such techniques included the direct address by actors to the audience, exaggerated, unnatural stage lighting, the use of song, and explanatory placards." - wikipedia.
To fix this Brechtian effect the z axis brings to video, you wave the z axis back and forth, gently: this waving motion breaks the focus on the z axis and then the focus goes back to the x and y axis presentation.
It matters if you wave the z axis in a 360 degree circle as compared to moving in either the x or y directions.
When you wave the z axis in a circle the focus remains on the z axis, but wave the z axis in either the x or y axis direction and the focus moves away from the z axis.
To test this, do the 3D test described before
, but this time wave the hands around to the left and right, then up and down, then in a circle -You will see the Notepad screen becomes more or less visible.
Back to discussing 3D displays now, on a volumetric 3D video, the z axis when shown can be put into context of the x and y axis, because the eyes look at the z axis, then they look at the x and y axis.
To move the eyes from the z to the x and y axis, and keep focus, the eyes do not move in a circular direction - like your rolling your eyeballs in your head.
So, to define what 3D effect is : The mind concentrates on the convergence, then back to the focus and convergence, because concentrating on only the convergence and not convergence and focus may create the Brechtian distraction: not being able to focus on the convergence and accomodation seen in 2D is not a good thing, it's old man eyes.
Wikipedia says the root word of Presbyopia is Old man + sightedness, it sets in at around 40+ years of age: some people think 3D is Awesome, so old man eyes may make the world look Awesome, making the concerns 2D brings moot.
To tell a story, contrast zero parallax with positive and negative parallax: the main story running time is made up of over the top Brechtian theater - when the plot driven part of the story is shown, it gives feedback to this. Seeing convergence and focus in a 3D film is seeing 2D, or zero parallax - there is no Brechtian effect from the z axis, it's all story driven.
The story is told in z axis 3D, then 2D shows this story in a new light. In subliminal marketing, it may be that one characteristic of the topic subject is bolded and another characteristic is muted: the bolded characteristic is in 2D and the muted characteristic is in z axis 3D. 3D (Brechtian effect), gives a critical view of what happens in 2D.Audio version