A really cool looking visual effect is light painting.
In photography, the effect is achieved by using a slow shutter speed, but recently, I wanted to obtain the same effect in video. Turns out it’s a bit more complex than changing your camera’s shutter speed, but if you use Apple’s Motion, the effect can be done quite easily, in just a few steps.
Import the footage that you want to use for you video light painting and title the group subject.
Create a new group and title it null object. Create a new shape, I’ve chosen a rectangle, but it really doesn’t matter. What does matter, though, is to make sure that it has no fill and no outline, basically making it a ghost shape.
Track your ghost shape to whatever you are going to use to do the light painting with. In this case, I’ve decided to use my subject’s fingertip.
Wherever you want your subject to start light painting, add a particle emitter, the one that I’ve decided to use is the Magic Dust emitter as I have found that it gives you a pretty good place to start.
Add a match move behavior to your particle emitter and use the ghost shape as its source.
In the inspector for the particle emitter, change the life parameter to 10 and the speed parameter to 0.
Under the particle, change the random motion amount to 0.
Change the gravity parameter to 2.
This is personal preference in terms of what thickness of light you are going for, but for this, I’ve changed the scale over life to about -55 for the scale at start of life and -25 for scale at end of life.
This is also a preference depending on what color you want your light to be, but here I’ve changed my light to a blue-ish gradient in my inspector.
Add a gaussian blur to your light, making it look more natural. The amount should be either a 1 or 2.
THAT’S PRETTY MUCH IT!!!
YOU SHOULD NOW HAVE SOMETHING THAT LOOKS A BIT LIKE THIS: