Stuff to do on a greenscreen

[ciencin]

So I finally got a greenscreen and going to be trying out a few things with it in a week.

Basically its only the backdrop so I'm limited with stunt effects, but want to try out some stuff that wont be just a person standing with the background changing....

Ideas I got so far:
- wind effects with a fan
- trampoline + greenscreen (not sure if its going to be possible to edit the footage since dvx doesnt have a a high frame rate...)
- body movements: walking, arm movement etc
- some breakdancers in front of the greenscreen

Anybody can recommend stuff to try? I used a small greenscreen once just for a body shot and learned my mistakes regarding lighting etc so this time around I want to try out some other stuff that hopefully wont be too hard

 

[El Director]

I'd say try some stuff with different hair styles to learn what your limits are. Do stationary hair and moving hair.

Also, if you can, set the screen up behind a car, stick some actors in it, and try to do a driving scene. You'll learn how to key with glass. Sometimes you can key through it, but other times you'll find yourself adding virtual glass. Both are good to practice.

Add some tracking markers and try some matchmoving.

 

[clang]

Yeah, film as many different types and speeds of movement as you can, some nasty edges such as hair, and some transparent stuff. I'd also suggest filming a few greenish objects, just so you can test how green you can cope with before it goes 'transparent'.

Of course, you're not only testing your raw footage, but also how good your greenscreen/chromakey software is.

Some of the above tests will fail, i.e. you just won't be able to key them properly - better to find out your lighting/shooting/keying limits now rather than in the middle of a real shoot.

 

[El Director]

And to build on what Clang said, something I did when I started getting into greenscreen was to download a bunch of gs frame grabs off the web. As high rez as possible. This allowed me to learn how to key different kinds of green, different lighting, and different objects. Granted, they're only stills, so you'll only get so far, but it's a good exercise. i also grabbed stills from the all gs version of sin city and keyed those. This inclucude removing mics and lights using a garbage mask, and turning the blue yellow bastard yellow.

 

[stuckfootage]

>Ideas I got so far:
>- wind effects with a fan
>- trampoline + greenscreen (not sure if its going to be possible to edit the footage since dvx doesnt have a a high >frame rate...)
>- body movements: walking, arm movement etc
>- some breakdancers in front of the greenscreen


It sounds like a lot of fun. As you probably know, it's super-important to light
the greenscreen evenly and get the talent as far as possible from the screen.
Try two people shaking hands.

 

[ciencin]

>

It sounds like a lot of fun. As you probably know, it's super-important to light
the greenscreen evenly and get the talent as far as possible from the screen.
Try two people shaking hands.

Thanks for all the advise. Im going to see if I can set up the greenscreen + car option, but that would depend on the weather on the day

Since the even lighting was mentioned,, how hard/tedious would it be to key out a person if the lighting is uneven?

eg: half the face lit, other in shaddow?

 

[clang]

Doesn't matter how the talent or other foreground stuff is lit (other than a few things like ensuring they're not getting accidentally lit with green bouncing off the background, that particularly applies to shadows) - it's the lighting of the greenscreen background which makes or breaks the keying.

Sure, you can fix (or at least improve) many mucky keys in post, but it quickly degenerates into manually keying most of each individual frame (unbelievably tedious), thus destroying most of the benefit of greenscreening in the first place...

 

[El Director]

There are some tricks I've used when I don't have even lighting. The best thing I've found is to use a secondary color corrector to boost the saturation of the greens only. Doing this will bring the greens to a more uniform color.

For the car bit, I've just done that in a garage and it worked well. I place the screen lights on top of the car, and can have some other lights to light up the actors. Go to the photos section on my site in my sig for an example.