Green Screen car advice

T

TomLenham

Well-known member
Hi guys,

looking for a little advice if anyone can help - we have a shoot next month which involves some car shots (head on 3 shot of talent driving and talking with each other). We have almost no time with the talent (literally 20 minutes), so rather than using a lowloader we're thinking of shooting on green screen and comping the road in afterwards. We have to shoot exterior as we have to go where the talent are and the only space is the venue parking lot. My question is this - would you wrap a big screen around the back of the car, or would you green screen the interiors of the windows and light with small leds inside the car? My instinct is to have a large cyc around the back of the car, but I'm wondering what happens to the key when its being shot through 2 layers of glass (ie front and rear windscreens) - will it end up mushy? Thanks in advance for all advice!
Tom
 
Large cyc behind. Proper lighting. Flag off unwanted reflections on windows. Shoot 4k if you can and frame so you can add a little camera shake in post to simulate car movement. Might incorporate a side light which can be rotated in at times to simulate movement.
 
How real does this have to look? TV sitcom real? Or big budget movie real?

Definitely a screen behind the car. But there are going to be issues. As David said, be VERY careful about green spillage into the car and onto the talent. And make sure the screen is lit as evenly as possible.

The problems with getting big movie real are several. If your background footage has street lights and such, you're not going to have matching variable lighting on your talent, so it's not going to look real. Adding camera shake in post is also not going to look real -- in reality, the people 'bounce' separately from the car interior. Having some big, strong people shaking the car a little bit would be more realistic, but again it likely won't match any shake in the background footage.

If you're going to shoot outside, then take special care to get clean sound on the dialogue. You'll be adding sound effects in post -- car motor sound, 'room tone', etc. -- but you don't want unwanted background sound in your dialogue.

If all you need is TV sitcom reality, then it's a whole lot easier.

Only 20 minutes with the talent? Wow. Good luck.
 
To give you an idea how glass may behave with or without reflections, take a look at the pink cellophane in this test. The subject is outside in front of a screen. Both the subject and the screen are in full sunlight. The screen is flopping around into full light and shadow. You can get it much better than this. I was having problems with After Effects not liking AVCHD at the time. The foreground and background were not locked to each other, so you will see that the camera shake doesn't match. This is 4:2:0.

https://www.youtube.com/watch?v=STmRLhwpdrM
 
One other possibility to consider is masking the window area in post - that would avoid problems with green screen lighting etc. BUT masking in post is potentially a horrifying amount of work, as it requires moving the mask position for every single frame in the shot whenever it moves, so I'd only consider this if:
- the shots are locked off (i.e. the camera doesn't move)
- and the talent doesn't move much in front of the windows
- and you have a patient and talented post person to do all this masking (of course you'll need such a person anyway, to get the background footage composited in a realistic way, unless you're going for a stylised look).
 
You probably already know this... But I have found a Schneider True Polarizer filter comes in handy on occasion when shooting through different window glass. I keep a 138mm drop in on hand.
 
I just reread the car section of the DV Rebels Guide and interestingly Stu recommends black instead of green for a screen, with a couple of exceptions.
 
You must log in or register to reply here.
Back
Top