Outdoor chroma key attached to Van?

F

firehawk

Veteran
Hi all.
Had an idea.

My van has tall flat sides. Wondering if I could attach foam backed fabric chroma key green to the side of it for a fast exterior keying solution?
Foam backed fabric can have grommets on the side so cords could be used to pull it and hold in place.

I've never keyed outdoors. Could this idea omit most of the lights that are needed indoors? And also help easily maintain a consistent look if cutting with other footage of talent outdoors at the same location?
Thoughts?
 
Have you shot and edited green screen much? I see technical reasons why it might not work. You need to figure out what you are shooting and make sure that the green screen you are using completely encapsulates your subject and it's corresponding movement. What about floor line if you need to key a standing subject or full body length sitting or moving? Most daylight outdoor lighting is going to be flat so that works. One challenge will be exposure consistency though. Not a problem on a clear, sunny day at midday, but could be a huge problem on a cloudy day wth clouds moving and fluctuating your background exposure. The other challenge is that you want exposure lower on your green screen than your subject, how would you handle that if you are getting nuclear bright sunlight on your green screen? Are you going to blast your talent with 18k HMIs to get a higher exposure level? As in all cases, testing is best. You can rent a green screen and try it. Personally, I would tend to shoot green screen on a stage where the lighting and exposure is under your control. Also, a big green screen outdoors is no different than any other scrim, it's a giant sail to catch gusts of wind so that could be a nightmare too. My main question would be, "to what end?" Why shoot green screen outdoors when most factors are beyond your control outdoors? Sound, lighting unless you have big budgets and crews, wind will be an issue, etc. There is a reason why you see hardly ever see Hollywood production shoot green or blue screen outdoors (other than once in a while for a quick one-off) and why they will build blue and green screen on stages that stretch hundreds of feet wide and deep instead.

I shot on Cosmos, the TV series and there was a shot we did at the Grand Canyon with Neil DeGrasse Tyson where we shot Neil at the edge of the Canyon with the Canyon in the BG, then shot a clean plate of the same Canyon BG, then floated in a 20x20 green screen behind him. It's a shot where he raises his hand and the layers of the Grand Canyon separate. It was a total PITA shot to capture but the exposure and shot worked fine. But it was raining on and off, the wind was gusting and it was actually dangerous playing with a 20 x 20 green screen at the edge of a 3,000 foot cliff. So green screen outdoors? Hmm...
 
firehawk said:
Hi all.
Had an idea.

My van has tall flat sides. Wondering if I could attach foam backed fabric chroma key green to the side of it for a fast exterior keying solution?
Foam backed fabric can have grommets on the side so cords could be used to pull it and hold in place.

I've never keyed outdoors. Could this idea omit most of the lights that are needed indoors? And also help easily maintain a consistent look if cutting with other footage of talent outdoors at the same location?
Thoughts?
Click to expand...

People shoot outdoor green screen all the time. What are the chances you'll be able to park your van exactly where the green screen needs to be? On top of that an inability to tilt your van wall like you would a frame makes it more of a hindrance. The consistent look doesn't just come from the same location, it's from the same lighting on the talent as well as what you're replacing the green screen with.
 
It would seem sensible to use a 'normally' gripped green screen - not be tied to the van.

However I would consider making your van into a gripping point(s)

My roofbars are drilled to accept doughty clamps and I have a device to go from towhook to doughty clamps.

This means for example if I parked my van behind a screen it would be simple to 'tie' (with scaffolding/speedrail) the top of the screen to the vehicle which could then act as a support and windbreak.

as noted above wind force even on 8.4 boards/sheets can be significant, 12.12 or more even more so!

on a side note I have also drilled the roofbars to accept a pair of bars (via doughy clamp) at the correct width for Dana dolly meaning I can simply offer a slider 2.8m above the ground :)

S
 
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With the new keying tools in NLE's these days its pretty easy to get a good key. That does not preclude however a proper setup with even light on the key and distance from the key bg. Or matching lighting on the subject in the key to whatever your "plate" or background is going to be. Quick and dirty is usually just that and in some cases it is just what you need.
 
The trouble I see is simply the effort you need to put in to get the green screen even and shadowless. Outside, on a cloudy day, then shadows will be soft, but how about a sunny day - you will be lighting with just a mega key light - so what will you fill the shadows in with? Reflectors? Real Lights? Sounds a real pain, and the positioning of the van will be very important.
 
...the times I have seen green-screen employed outdoors the green screen was quite large in size. A reason being that you don't want the shadows of the subjects to be on the green screen. Be the shadows of the subjects soft ( clouded sky ) or hard ( clear sky ).

Here are some pics I took of big-a** green screens, outdoors. These are from the set of "Battle L.A.":


IMG_1164 copy.jpg

IMG_1158.jpg
 
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Cool BTS shots JP. Do you know why they did that setup outside? Just size, no stages that large or ? I wrote up Guardians of the Galaxy II, I think they did some green screen on some HUGE stages, I think perhaps even in a Stadium?

Maybe for driving or car stunts?
 
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