Ultimatte-9 Operations Manual
March 1, 2000
61
Figure 25: Background Defocus
Menu
XXII. BACKGROUND DEFOCUS MENU
A scene viewed through a camera will show various objects at different levels of focus, depending on the
focal length of the lens, the zoom level, the iris setting and camera gain setting. Iris and camera settings
are directly related to the lighting level of the scene. When the lens is focused on an object at a specific
distance, this object, and other objects at similar distance from the lens, will look sharp. Objects that are
closer or farther away from the lens will have a softer and out of focus look. When compositing a FG
object into a BG scene, maintaining appropriate depth of field will yield very convincing images,
particularly when the FG is a close up of the subject.
In virtual sets, most BG scenes are computer generated and their viewing angle is changing in real time
to match that of the FG camera. These computer-generated images are very sharp and crisp. When
composited, these images will look natural when the FG subject is at a distance where both FG and BG
would be in focus. But when the FG subject gets closer to the lens, or the camera is zoomed in tighter
and sharp focus is maintained on the FG subject, the BG scene should gradually go out of focus. Some
virtual set systems provide means of “defocusing” the computer-generated images to simulate depth of
field by tracking the zoom function of the camera lens. While this can track defocusing while zooming, it
cannot track if the FG subject or the camera moves toward or away from each other. Other systems avoid
BG defocusing to conserve computational power of the computer for rendering more realistic BG scenes.
The Ultimatte-9 provides an alternate technique of tracking the depth of field. The Ultimatte-9 compares
the size of the FG subject to that of the video frame and, if the size falls between a minimum and a
maximum size set by the operator, alters the sharpness of the BG scene to simulate depth of field. The
operator also sets the amount of BG defocus at both ends of the automatic tracking range. Alternatively,
the amount of BG defocus can be controlled from an external computer, or manually from the control on
the Smart Remote.
SET MIN
Value
0%
SET MAX
Value
100%
Defocus
Transition Rate
Range 1-16
Online [ 1, 2, 3, 4 ] Active ( 2 ) FILE=
UM9-
Background Defocus Menu
Defocus
Mask
DEFOCUS
ENABLE
BLACK / WHITE
LEVEL
CONTRAST /
SATURATION
TEST
SIGNAL
BG Defocus
Sensitivity
BG Defocus
MASK
ENABLE
SET
MIN
SET
MAX
DEFOCUS
TRACKING
MASK
INVERT
%
%
(COLOR) BACKING
RETURN
DEFOCUS
CONFIGURE
%
1
