| The
most powerful video tool at your command is the
humble frame that surrounds the image. The four
sides of the display monitor determine what your
viewers will or won't see and how they'll see
it. This power lets you play all kinds of tricks
with images. You can make subjects float in midair
or animate things that are really not moving.
The
ability to defy gravity or move still objects
is based on two of the universal laws that govern
the video universe. Briefly, these laws are:
-
"Up" and "down" are always
parallel to the sides of the frame, no matter
what they are in the real world.
-
Movement
is defined by the edges of the frame, rather
than by motion in the real world.
So,
let's see how you can put these two laws to work
for you to create simple, but convincing special
effects. For faking movement, you'll need a colored
compositing background (though a hard blue sky
works well, too). For fooling gravity, however,
you'll need to bring along your imagination. |
What's
Up, Frame?
In
the real world, you spend your waking hours with
your eyes parallel to the ground, so "up"
and "down" are typically at right angles
to your two eyes. Because video displays are also
aligned with the ground, on-screen "up"
and "down" are parallel to their sides.
If
you tilt your head, your middle ears tell you
that you're off-level, while your environment
is still upright. But, if you tilt your camcorder
(and frame off giveaway diagonal lines), there's
nothing to reveal the angle. Viewers will continue
to believe that up and down align with the sides
of the frame. You can use this effect to create
steep and slippery slopes, or even to cancel gravity.
Why
would you create a slope? Mainly, to increase
the difficulty of climbing it or the excitement
and danger of driving, rolling or falling down
it. For obvious reasons, mountain climbing sequences
appear more perilous if the rock faces are closer
to vertical.
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Cars
look especially dynamic on screen when roaring
up steep hills or howling down roller coaster
drops. Incidentally, if you cut quickly from shot
to shot, canted on-screen verticals won't be very
noticeable to viewers. You can also use a tilting
frame to fake movement, of objects or the entire
scene. To use a cornball example, imagine Mandrake
the Magician commanding the coins to come to his
outstretched hand. Lo and behold! They slide mysteriously
across the table and into his palm. The trick:
- Get
an establishing shot of Mandrake and the coins,
emphasizing the horizontal tabletop.
- Frame
a close angle from the actor's point of view,
with his outthrust hand stretching into the
shot from the bottom, and the table edges outside
the frame borders. That way, the table-tilt
that causes the loot to slide is completely
invisible to the audience.
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