Green screen talent is often lit very flat, which makes it difficult to properly blend the talent in the background plate. One handy tool for dealing with this is the CC Light Sweep, a former Cycore plug-in that now comes standard in After Effects.
STEP 1: Add CC light sweep
After keying out your character’s green screen background, you need to add some edge lighting to properly blend them into the scene, especially if there is a bright light source somewhere in the background image. In the Generate section of the Effects pull-down menu, select CC Light Sweep.
STEP 2: Remove light sweep component
The CC Light Sweep has two components: a light sweep, which adds a light gradient over the top of the image, and the Edge light, which adds a light edge around the layers alpha channel. We don’t need the Light Sweep component, so lower the Sweep intensity to 0.
STEP 3: Set the edge direction
To make the illusion work, you’ll need to set the angle that the light is coming from. In this case, our light source is directly above the talent, so you’ll need to set the Direction at 0x+00 degrees. Also, increase the Width setting to at least 50 to properly display the light edge over the entire talent.
STEP 4: Add glow to soften the light edge
I like to add a slight glow to the light edge to make it more or less harsh, depending upon the background plate. Here, I’ve used GenArts Sapphire plug-in, S_Glow to add a subtle glow around the light edge.
STEP 5: Increase edge intensity as needed
By increasing the Edge Intensity setting over time, you can make it look as though the subject is getting closer to the virtual lighting source. Just set a starting level at the point where the subject is farthest from the light source and a final keyframe with a higher Edge Intensity level.
Media Alchemy, Inc.
Erik is president and executive producer of Media Alchemy, Inc., an award-winning media production company based in Seattle, Washington, that creates both broadcast documentaries and custom media for special venues. Using its media technology expertise, Media Alchemy has created everything from multi-screen HD movies to interactive theme park rides. Erik is also a journalist, with four published books and dozens of articles on media production to his credit.
Erik Says Keep in Mind…
Green screen talent is often lit very flat, which makes it difficult to properly blend the talent in the background plate. One handy tool for dealing with this is the CC Light Sweep, a former Cycore plug-in that now comes standard in After Effects. Light Sweep lets you add a bright edge to your subject, which is great for compositing a green screen actor into a bright background plate.
You can also animate the edge setting on CC Light Sweep to simulate a light source moving over or near your talent. Just set up three Edge Intensity keyframes, where the stop and the start keyframes are the same. At the point where the light source would be "over" or "near" the green screen actor, increase the Edge Intensity. This will brighten the edges of the actor just as the virtual light source passes by. You can also heighten the illusion by adding in a glow and adjust its intensity along with the CC Light Sweep intensity.
Media Alchemy, Inc.
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