When Children Can’t do Their Own Stunts

Although I have sung the praises of behind-the-scenes videos for Christmas productions, I have now made my fair share of them, thank you very much. So this year I am taking a stab at satire and have staged a series of behind-the-scenes gags to assemble into a "mocumentary" about our Singing Christmas Tree presentation. It's proving to be a great opportunity to play around with cheesy green-screen effects, all in the name of getting a few laughs before the live show begins.

In a segment about the children of church workers and how they busy themselves while their parents work on the show, I created a shot of three children dangling from a catwalk. THIS DEMO shows the process. We dangled a child hanging from a pipe a couple feet off the ground. The green-screen was lit as evenly as possible. The kids were lit with separate lights, avoiding shadows on the green-screen. I cropped out everything around the kid, applied the chroma-key filter, and added three such elements to a still of the catwalk. I used Photoshop to make an overlay of the lower part of the catwalk to composite over the kids' hands to make it look like they are holding onto the far edge.

Although it is best to light the green- or blue-screen as evenly as possible, I have found compositing software to be able to handle less-than-perfect lighting jobs. Final Cut Studio handled the job fine for two of the children. One of the children had stripes that were too close to the shade of the green-screen, but After Effects could zero in on just the shade we needed to remove. I suspect, however, that high definition would be much less forgiving.

Clearly this shot is nothing less than cheesy, as it is meant to be. If serious effects are needed, greater attention should be made to lighting the screen and matching the lighting of the background image. I have used this technique to composite an actor dragging a cross through miniature Jerusalem street with cleaner results.

I'll post the finished mocumentary later this month when it's done. I blow up the sanctuary sound booth. They had it coming.

Have done chroma-key effects?  Please share them in the comments below.

Post a Comment

Comment limit: 500 characters (about 100 words).
Inappropriate or offensive comments will be promptly removed.

Your Name/Handle: