Overview - 3D Postproduction: Stereoscopic Workflows and Techniques - page 23

XAxis
Figure 1.10 XY Space (2D).
Moving an area of interest in a 2D frame from side-to-side (i.e., horizontally)
moves it along the X-axis. Moving an area of interest up-and-down (i.e.,
vertically) moves it along the Y-axis. Moving objects on both axes results
in a combination of X and Y motion (diagonal movement) within the 2D
frame. Our experience of distance and separation between scene objects in
a 2D frame are indicated by 2D depth cues such as occlusion, relative size,
shadow, transparency, color shifts, and depth of i eld.
1.6.2 Z-Space (3D)
By simply adding another slightly different 2D view of the same scene in
an image pair, we create a 3D frame, transforming 2D space into 3D space
(Figure 1.11) . This space has a sense of in and out or forward and backward
as well as side to side. This additional dimension created by adding another
2D image is called Z and represents the “third” dimension in the term “3D.”
We call this illusory volume with X, Y and Z dimensions Z-Space . It is not
visible merely by looking at image pairs: Z-Space exists only within a 3D
frame. The illusion of 3D depth, as well as the apparent movement of areas
of interest within the volume of Z-Space, results from the changes in parallax
(horizontal separation and relative position) between L and R over time.