Wednesday, 16 March 2011

Compositing the green screen in After Effects

When it came to the post production stage of this project, I put myself forward to do the green screen parts which happen right at the end of the piece, when our protagonist (Richard is his name) gets cornered in an underground parking area.  This would involve a mixture of moving and static camera shots.

The first shot that I worked on for this part was a mid shot of Richard cowering in fear against the graffiti wall.  This shot was relatively simple as I only had to use After Effects to composite this and a rendered shot of the graffiti wall made by Nat.

Here is the original green screen footage:
video
In order to match his pose with the action figure that he eventually morphed into, I flipped the video footage horizontally.

Here is the rendered close up of the green screen.
In After Effects, I composited these together by applying a Keylight filter to the green screen footage, that keyed out any shade of green, which which would allow Richard to appear against the graffiti wall.  I scaled the graffiti wall until it looked as though it was very close to the camera in relation to Richard.  I then applied Masks around each motion tracker, in and set them to "subtract" the motion trackers so that they were absent and only Richard was present.
As you can see from this image, Richard does not fit in with the rest of the environment because he very bright, compared to the dark and eerie surroundings.  In order to solve this, I applied a Curves filter and I then reduced the brightness, so Richard was absorbed in the peril within the scene.
video

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