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672 Chapter 12: Animation
The motion search bounds defines the are in
whichthefeaturewillbesearchedforfrom
frame-to-frame.Thisboundsboxmoveswiththe
featurebox,sotheareaisrelativetothecurrent
feature at each frame. It ’s important to estimate
this search area well. If it’s too large, the matching
process will b e unnecessarily slow and there’s more
chance of other features in the search area making
the search ambiguous; if it’s too sma ll, track ing
errors will occur. It might be useful to review the
movie that will tracked on a real-time playback
device like a video deck and estimate feature
moves beforehand. If you set the Max Move/Frame
spinnertothemaximummovebeforecreatingthe
tracker,itsmotionsearchboundsboxwillbeset
to accommodat e this move for you. You can also
adjust this box at any t ime in the Movie window.
Note: It’s possible to change the search b ounds box
for different frame ranges in the movie, s o you can
optimize your search capabilities. See Keyframes
and Position Data (page 2–679).
Working with the Movie Window
Displaysthecurrentframeofthemoviebeing
tracked and any active tracker gizmos for that
frame. You can open and close the window using
the Display Movie check box in the Movie rollout
or minimize it using the standard window t itle bar
controls.
When you first open a m ovie, 3ds Max sizes the
window so it will fit on the screen and this might
result in an automatic zoom out if the image is too
big.
You can resize the window by dragging its sides or
corners. You can zoom around in and out of the
window using the tracker gizmo controls.
Wor k ing with the Track er Gizmos
Thereareseveralwaystoworkwithgizmosinthe
Movie window .
• Selecting: You need to select a gizmo to work
on it. You do this by clicking an ywhere inside
itsboundsintheMoviewindoworbyclicking
its entry in the tracker list bo x in the Motion
trackers rollout. The selected gizmo displays
positioning handles at the corners of both its
bounds boxes. You can also select a gizmo by
typing its number on the keyboard. A selected
gizmo has click-selection priority in the Movie
window. If several gizmos overlap, they make it
hard to select and adjust the gizmo you want.
You can select it first in the Motion Trackers
rollout list; it remains selected for adjustment
when you click it in the Movie window.
• Zooming: You can zoom in and out on the
selected gi zmo by pressing the
I and O keys,
for “in” and “out,” respectively. Each time you
press
I or O ,thewindowzoomsinorout
by a factor of 2 and centers the selected gizmo
in the window. Pressing
R resets the zoom
factor to 100 percent w hether you have a gizmo
selected or not. The Movie window has to be
theactivewindowforanykeyboardcommands
towork.Youcanmakeitactivebyclickingit.
• Ta b b i n g : You can move among successively
numbered g izmos by pressing the
Tab key. If
the gizmo you’re searching for is out of view,
becauseyou’rezoomedin,theimagewillbe
repositioned in the window to bring the newly
selected gizmo into view. Tabbing while you’re
zoomed in provides a quick way to step through
the gizmos to check their fine positioning .
• Positioning: Youcanrepositionagizmoby
dragging anywhere within its bounding boxes,
providing you don’t click one of the eight
box-corner handles. You can nudge a gizmo in
single increments by pressing one of the arrow
keysonthekeyboard.Theminimumincrement
that a gizmo will move depends on the zo om
factor and the subpixel-tracking level. The
increment is the smaller of either a single screen
pixel in the current window or the subpixel