Tutorial of the Trailing Effect filter in Video Action
Today we have a
quick visual effect. I first recall seeing this effect in the
psychological thriller Jacobs Ladder and later
in The Mask It looks like a person is shaking
or moving at an extremely high rate of speed. It was used on
television in CBSs series The Flash and more recently
on Foxs X-Files to portray a villainous bug-like
entity. Try to keep your head as we use two filters to generate
The Video shoot
is about 8 times as long as the effect. The camera is steadied
on a tripod and the talent moves about the scene. In this case
I sat in a chair and wiggled my head about for 40 seconds. The
final result is about 5 seconds long. Shoot a few minutes of
footage with a person moving from place to place within the
scene and you are close to the manic speeds of Jim Carreys
alter ego in The Mask.
Place the clip
on track 3. The next step is to speed up the clip. Right click
on the clip and select Speed Change. Change the setting to 800%.
Next copy the clip
and place the copy on a track below the original so that it
lines up exactly. This is the clip that that will have two effects
applied to it. One filter effect is the Trailing Filter, however
the filter only works with an alpha channel transparency. We
will use the second copy of the clip and the Transparency Filter
to generate the alpha channel transparency on the fly.
All that needs
to be done to the Transparency filter is to change the Foreground
Transparency to about 90%. Because we are overlapping the same
clip on itself the Transparency filter will not show any effect
in the Preview Window.
Next apply a trailing
effect to the clip. This effect is not found in the Apply Effects
dialog. Instead it is found under the Tools menu. Select the
Wind or Defocus setting and set the decay setting to 1% for
maximum trails. Setting the filter to 0% decay is worse than
1%. Because the trails never clean up and the video will darken
during the render.
there is to it. Please note that although the effect is quick
to generate, use it sparingly. The combination of these filters
do take more time than normal to render.
to see an mpeg clip of the effect
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