[photo-3d] Re: Quiz: Movement of clouds/direction of shoot

[abram.klooswyk@xxxxxx]

Interesting Quiz George! (You should have used the poll 
function of the list).
The quiz resembles in a way the question on the left or right 
side shooting from plane or train.

>100 feet separation hyperstereo with a single camera.
>...clouds are drifting very slowly from left to  right. 
>Should you take the LEFT picture first or the RIGHT, 
>and why?

The easiest way to imagine this is (I believe) to suppose a 
hyper shot _without_ clouds, and then superimpose _movable_ 
clouds on left and right hand picture. This can be done in 
projection with one stereo and two mono projectors (with 
appropriate pola filters). A charming fact is that similar 
movement effects have been used in _mono_ projection over 
a century ago, with lantern slides.

Taking the left picture first means that the clouds will have 
moved to the right on the right hand picture, when you take it
next. Therefore the cloud separation will become _larger_ then 
the separation of the farthest "ground target", so will be in a 
farther plane then the ground far point, in 3D viewing.

But with the right picture first the clouds on the left hand 
picture move, but _again_ to the _right_. So now the 
separation of the clouds will become _less_ then far point 
separation, so will be closer in the 3D percept. How far 
closer of course depends on cloud speed etc.


So which picture first? 

Complications occur when close clouds overlap more distant hills or 
mountains. Apart from several spoiled shots I have seen (and made 
myself) some shots where clouds, partially overlapping mountains, 
moved closer in 3D. This can be nice, unless they become cut off by 
the window when they come too close, and unless they cast shadows on 
the mountains :-(). 
But a few close clouds only in the middle of the scene can be nice. 

However, in many, maybe most cases non-background-overlapping clouds 
a little more distant than horizon mountains are fine.

So I believe the answer to "which first" is not always the same.
I look forward to other opinions, and to they only right answer:-).
 
Abram Klooswyk


 

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