Re: Floating window #theory #hasImages #alignment

John Rupkalvis

Floating windows are a very good way to permit moving objects into negative space (in front of the screen or other image plane), of which there is much more room than positive space (behind the screen or other image plane).  Since convergence is normal and divergence is not, you can easily fuse objects that are many times more in front of the screen than behind it.   

Since stereoscopic displacement is lateral only, window violations occur only at the sides, not the top or bottom edges.  However, for esthetic reasons, good stereoscopic compositions usually do not have cropping occlusions of certain types of subjects, such as the top of people's heads.  This looks bad even when they are behind the screen, but even worse in front of the screen.  

Artistic considerations include composing for all three dimensions, not just two like in squashed 2-D photography.  Sometimes it looks good to just avoid composing for edge cropping.  However, recognizing that this is not always advisable for all subject matter, the floating window can solve lots of problems.  The main consideration is that the window is floated such that no part of the image that is in negative parallax is seen in one eye but not the other.  Floating the window solves this very nicely.  And, it does not even have to be the same on both sides.  Having the window closer on one side than the other can look very pleasing for some subjects.  In 3-D, the stereo window "frame" can actually be at any angle, and done appropriately for the subject, can look very pleasing. 

John A. Rupkalvis


On Wed, Jun 17, 2020 at 5:26 AM Stereopix Net <contact@...> wrote:
Re floating windows, I almost got the concept in the past with stereo projection. But am even less clear on how you do that with a sbs displayed or printed image, or even on a 3D display device. Can someone clarify this, preferably with an actual example where this is used to get rid of the window violations without moving the subject back so far from the window? e.g. with the man on the girders image. I generally dislike window violations, finding them distracting from the 3D effect, but can tolerate them somewhat on the bottom edge. -Linda N

First notice that:
1) when you horizontally translate the images (respective to each other), you move the whole scene in depth
2) where you cut the image sets the depth that will be displayed at the depth of the medium (screen, paper, etc.)
By combining 1 and 2, you can create a floating window : the real window is still on the medium (set by the cut), but you have a floating window created by the edges of the content (that do not use the whole space).

Here an example with exaggeration (probably too much forward). Normal window top VS floating window bottom. LRL. The two examples have the cuts (in black) aligned in depth to see the two examples simultaneously.
In situation, the black cuts and the gray "empty" space are supposed to fuse with the surrounding to make them disappear.

This is one way to view it. There are other viewpoints to interpret it that are equally valid.

Using it to avoid window violations that you did not saw at shooting can be seen as drawing a simple 3D window.
Just remove (replacing by empty space) the parts that are seen by the wrong eye :

You can also remove the same amount on the other side (of the other eye) to move the two edges forward (in the previous example, only the left edge is floating)

It is a quick explanation, with lots of refinement not detailed, but I hope it helps you to do the first step in this concept.


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