-
green screen motion tracking w/ RED camera
Hello Anyone! 🙂
I’m a director at a motion graphics company who has done a lot of TV and Music Video work with After Effects. Most of our techniques have been done in camera using stop motion animation. We’ve used AE for 10 years but I personally haven’t used it for what I’m about to get into. So any tips or things to look out for would be very very helpful as we are shooting in a few days. Naturally I have some questions.
We are shooting scenes of a project (Shooting with the RED Camera) where we have a character in a black suit and tie who is wearing a green screen hood. He is acting out specific motions in front of a larger green screen syc. We’ll be using AE to key out the background and his head. He will be a headless man running around. Then we’ll make animated sequences in AE and track them to his head. The sequences that we create in place of his head must track perfectly to his body and the backgrounds must be stable.
I’m wondering :
Should we have multiple tracking marks on his head or just one? Also he will be wearing a white shirt and tie under a black jacket so will this spill heavily onto his collar? If so how can we minimize this? Should we black tape the inside of his shirt? Also… Do we need to have Tracking marks on the background if we are expecting those backgrounds to be stationary? will the background marks interfere with the tracking marks on his head?
Like I said. We’ve done a lot of work in the past but this is new to us. It’s also last minute and with a tight deadline. Any help would be appreciated.
Best.
b -
8 Replies
-
Hi Brian,
If you want to track elements to the head it’s going to help to have multiple markers. But it all depends on what exactly you’ll be compositing in. If you just need to lock the position of the animated element to the ‘head’ then you’d be fine tracking just a single marker (as long as it’s always visible).
If you plan on tracking scale and rotation too, it gets a little more complicated and you’ll need multiple markers on the head.
To minimize green spill on white clothing you’d typically want to stay as far away from the greenscreen background as possible. And the lighting needs to be right. Usually I’ll light the subject with some magenta gels and color correct the slight red cast out in post. But the slightly red-ish lighting will help reduce green spill on the subject. And definitely don’t underexpose the subject. You want the whites to be significantly brighter than the green background – which will help separate them when you’re keying. I’m not sure what you mean by ‘black taping the inside of the shirt’.
If the camera is locked on a tripod you won’t need tracking markers on the greenscreen and you’ll be happier leaving them off since you’ll need to garbage mask them all out.
Good luck,
Barend
Raamw3rk – digital storytelling and visual effects
-
Also one thing to keep in mind (and this is experience from something I did along the same lines) is that if you are removing the head, you might have to put something behind it, ie the back of the shirt and collar that would be behind his head. It really depends on what movement you plan on your actor doing.
-
This thread is interesting. A friend replaced the head of a dancer with drawing. I don´t know if the dancer had multiple trackpoints on his head, but I he had just a colored green jockey or something.
https://www.smog.tv/ It`s the one called “Mono” in the bottom-right.
“And definitely don’t underexpose the subject. You want the whites to be significantly brighter than the green background – which will help separate them when you’re keying.”
Why should it be more dificult to separate a darker subject from a green screen?
Is it better to underexposure the subject in post? Why?cheers
Seb -
It’s not so much the issue of the relative brightness. You can key out dark areas just as well as bright areas.
What I meant to say is: if you don’t light the subject with enough light, the green cast caused by the greenscreen is going to spill all over the white shirt – causing it to come out green in the image.
Hope that makes more sense now.
Bar3nd
Raamw3rk – digital storytelling and visual effects
-
Got it. White is always easly colored by color lights or colored reflections, but you should have any problems if you lighten him with a little bit of magenta and overlight the greenscreen (So he the subject is under exposure)
¿Wrong?
-
No no no,
Although you don’t want to underexpose your greenscreen (no too much anyway) – overexposing the greenscreen will cause more green light to bounce around causing spill.
So if there’s white in your foreground elements you want to make sure you put enough light on it to ‘blow out’ the green spill.
Bar3nd
Raamw3rk – digital storytelling and visual effects
-
Thats what I mean. I sayd overlight (not overexposure) so the greenscreen is for example in a f5,6 and the the subject is in in a f16 if you spotmeter them. And you shoot the camera with a f5,6. The green cast caused by the greenscreen should not go spill all over the white shirt now. Otherwise, it should not exist green cast over the subject.
¿I am still wrong?
(My english is not the best, its hard to express myself)Cheers
Sebastian Ballek -
Brian, I am trying to do a similar thing in a project I am working on- having a headless dancer. However, I do not need to track anything in place of the head. I was hoping you could give me tips on the actual green screening part of it- matching the hood to the screen, making the hood, etc. I really appreciate it if you have time. I know you have a tight deadline on your own project.
Thanks,
Amy
Reply to this Discussion! Login or Sign Up