Adobe 25510629 - After Effects CS3 Professional, Руководство пользователя

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96 How to
The black box in the Input Offset grid control represents the layer plane. It does not change
to reflect the size or orientation that is set by using the controls on the Scene tab. If you
change the Input Offset so that any part of the image lies beyond the black box (see the pink
areas in the previous graphic), that part is cropped from the image. Conversely, any places
where the edge of the grid is within the layer plane (see the checkerboard areas in the previous
graphic) appear either transparent or black, depending on the set. The following graphic
shows what would be displayed with the Input Offset settings from the previous example.
Given how these controls function within the layer plane, these controls are useful in the
following situations:
Repositioning an input clip in a VirtualTrak scene. VirtualTrak sets lock the Input
Position In Scene controls that you usually use for this purpose. These controls are
particularly valuable in this regard if the input clip is a few pixels off so that the subject
appears from the middle of space rather than emerging from behind a door, pillar, or other
foreground element.
Zooming in on a part of the image by increasing the scale of the source and, if necessary,
repositioning it for the desired framing.
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The Input Offset controls require hardware capabilities that not all video cards support.
For those video cards, you may see artifacts around an image when it does not fill the
layer plane. In some cases, cropping the edges slightly with the Input Cropping tool can
delete the visible repeat. For more information, see
“Cropping the edge of a frame”
on page 84 .
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Vertical, horizontal, and angular movement is relative to the native coordinates of the
source. If you rotate the source or flip it in either dimension by using the position and
orientation controls on the Scene tab, then the image’s motion seems contrary to the
mouse’s movement.