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Greenscreen editing assistance needed

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David Goodwin
Greenscreen editing assistance needed
on Feb 13, 2015 at 3:46:42 pm

Hello, I'm a bit of a beginner with After Effects and I'm trying to key out the background for this video. I attach a still of the original shot. As you can see the problem is the original footage isn't as clear as I expected despite HD camera and the greenscreen is so badly wrinkled I can only pull a half decent key. Any advice on how to correct this? I used the preset Keylight spill suppressor and modified the values.

This is the original:

The result is grainy and takes fragments out of the foreground and vice versa.

Any help would be appreciated, thanks

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Dave LaRonde
Re: Greenscreen editing assistance needed
on Feb 13, 2015 at 4:56:53 pm
Last Edited By Dave LaRonde on Feb 13, 2015 at 7:47:50 pm

Ugh. That is one butt-ugly shot. Sorry, but it is. I wouldn't even bother trying to key that because of the many problems it has. The subject is out of focus. The background is wrinkled. There isn't any lighting... okay, the image is lit, but nothing that helps with a chroma key, that's for sure. The subject's too close to the background.

You need to give yourself a fighting chance at success. You need to re-shoot.

So here's what you do -- google the terms, "lighting for green screen" and "lighting for chroma key". You'll find some good advice on setting up a proper chroma key shot. Here are the basics in a nutshell:
  • Get the subject about 6-8 feet away from the background
  • Smooth out the background
  • Light the subject separately from the background... no lights on the subject spilling onto the background. They don't have be fancy lights, but you do need some. Or shoot outside, making sure the background is in shadow.
  • Make sure the light on the background is FLAT -- no hot spots, and even all over. If you shoot outside on a sunny day, you'll notice this happens automatically simply by tilting the background a bit in various axes to hide it from direct sunlight.
  • The background doesn't have to be really bright, screaming out "GREEN!" It can be a little on the dark green side. In fact, Keylight likes that better. Again, shooting outside and following the previous tilting tip does that automatically.
  • Focus up on the subject

You'll notice there isn't anything above said about how to pull a key in AE. That's because you have far more fundamental problems with that shot than figuring out how to pull a key in AE.

Once you've given yourself a chance of success by following the steps above and you've got a nice-looking shot, you'll find Keylight tutorials right here on the COW. They're good. Avoid YouTube tutorials made by high school kids... they barely know what they're doing -- cripes, they can barely find their posteriors in the dark using both hands (in AE terms) -- and their technique is almost always sloppy or second-rate.

Then you'll have success at chroma keying. Once you re-shoot, that is. Chroma key success begins with getting good shots, not just something you set up & shoot in 5 minutes.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

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Kevin Reiner
Re: Greenscreen editing assistance needed
on Feb 16, 2015 at 9:37:03 pm

I agree with everything Dave has said. It's just a really bad image. What camera are you shooting with and what settings? It looks like you had to really bump the ISO to get an image, which introduces a ton of noise. You need more light and need to put more distance between subject and background. If you are on a DSLR, be sure to do a digital zoom-in to check your focus. Hope you can reshoot, because that will be difficult to fix in post.

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