Grass Valley Zodiak v.6.0 Mar 15 2006 - Manual (Page 85)

Zodiak — User Manual 85
3-D Digital Effects Concepts
All post transform functions are made relative to the monitor screen frame
of reference. For example, a positive X post transform always moves to the
right side of the screen.
Front and Back, Near and Far
Pictures manipulated by a Zodiak Transform Engine have front and back
sides, each of which is revealed in turn as the picture spins or rotates. After
a picture has been translated it can be difficult to determine which side was
originally on the front and which was originally on the back. This distinc-
tion can be important when, for example, different sources are being
selected for different sides of an effect.
The Zodiak system uses a “Near” and “Far” convention to ease system
operation. Near is always the side of the picture that is visible (facing
toward the viewer), and Far is the hidden side of the picture (facing away
from the viewer). The current Near side can be either the front side or the
back side of the picture, depending on orientation. For example, to change
the source on the visible image, just change the Near side. To change the
source on the hidden side, change the Far side. You don’t need to know
whether the image being changed is actually the front or back side.
Transform Numbering Systems
The Zodiak Transform Engine uses the following numbering systems to
precisely define picture locations, picture size, and picture rotation and
spin.
Screen Coordinates
The Zodiak Transform Engine accommodates two different aspect ratios,
4 x 3 and 16 x 9, selectable via the Video Standards menu. In 4 x 3 mode, the
screen is six units high and eight units wide. In 16 x 9 mode, the screen is
18 units high and 32 units wide. The numbering system begins in the center
of the screen, and has the standard horizontal X axis and the vertical Y axis
(
Figure 55 ). For simplicity, examples in this manual use the 4 x 3 aspect
ratio.
These coordinates can be used for monitor screen locations (channel target
space with default global channel), or they can be applied to picture loca-
tions (channel source space).