Vehicle and green screen, outdoors
Posted 30 August 2010 - 12:42 AM
I am preparing for a green screen shoot for a music video. First off, I am low budget, as this is for an art commission. Therefore, I am seeking the best solution that avoids expensive rental equipment and costly post production techniques or software. I am willing to accept some imperfections, but want to avoid a disaster, too. I have some experience with film and video work, but have tons of experience as a still photographer, and am skilled at lighting. I believe in lighting it right with what we have available, and minimizing post-production work. I am shooting on a Canon HV-20 and I will be editing on Final Cut Express. I have about eight relatively low-power tungsten lights (500 watts - 2000 watts) available. I hope my project isn't too small beans for a reply!
My "studio" is the north-facing wall of a building. The core imagery in the video will be a vintage pickup truck with people riding in the cab. Mainly we will shoot through the windshield and see out the back window, and occasionally someone will be seen in the bed of the truck. In this shot, the hood of the truck, and sometimes the roof, will be seen. One shot will be from the back of the truck looking into the cab and out the front over the hood. I am hoping also to get a couple "full body" side views of the truck. This is a big order, I know, for a low budget shoot.
What concerns me most is direct reflections of the green screen off the glossy paint of the truck. I am familiar with techniques to gobo the reflections with black material. That may work for the tighter shots, but I do not have the rigging necessary to do that for the full body shots. And I can foresee that there will still be areas that get green reflections at the edges.
I have read several posts on green screen, but would like to get some specific advice from professionals regarding the troubles and solutions to shooting vehicles on green screen.
Posted 30 August 2010 - 06:42 AM
Depends what you mean by "costly post production techniques or software". I'm not very familiar with Final Cut Express, but the fundamental issue here is that the truck is reflecting the green because, well, it would otherwise be reflecting what the green is supposed to represent. Even if you could just remove all the green reflections from the vehicle, that'd affect your ability to produce a convincing composite, as the vehicle reflecting its environment is part of the illusion.
This is an issue (if not quite a problem) at any level. Halfway decent greenscreen software will pick up the reflection of the green in the vehicle and make it go slightly transparent, which may not give you a result you'll like since the background video probably won't represent a convincing reflection. Because of this you might end up wanting to isolate the "reflection" parts of the green from the "background" parts of the green, so you can flip and scale your backdrop video to create a more believable reflected image. Doing that isolation will require some work in software, but it's the correct solution really. You can make things a little easier by shooting the vehicle in such a way that the green reflections are somewhat separate from the green backdrop, but that's something you'd have to work out on a shot by shot basis.
Then you have to realise that if the vehicle was actually driving along, it'd probably see reflections in all kinds of places you actually don't have green. I'm sorry to give you a postproduction solution to what I suspect you would have preferred to solve as a practical problem; if you really, really don't want to get involved in too much postproduction, you might consider renting a big video projector and doing it as a back projection, so you can get it all in camera. Tricky, though, and probably requires the use of more practical effects to make it convincing.
Posted 30 August 2010 - 08:18 AM
Thanks for your reply. You have given me another angle to consider. It hadn't crossed my mind that what replaces the green reflected on the truck should be realistic reflections. I had only imagined, as you say, a practical solution of eliminating reflections. I will consider that approach. I do not mind a bit more work in post, just I am not sure what the limitations of FC Express are. I am quick realizing that a full-on test is in order to see where things fall.
Back to practical solutions, I thought of dulling down the finish on the truck. I cannot see myself coating the finish with 20 cans of dulling spray (do they even sell that anymore?), but I did think about dusting the surface with talcum powder (cue chorus of laughter) or some other stuff. Showing an immaculate vehicle finish is not critical. The form of the old truck is enough to carry the idea.
Also, I did not mention that I am using seamless paper that is made for green screen.
Posted 10 September 2010 - 09:48 PM
I do think you'll need to worry about compositing the reflection though. You can probably use your framing to minimise how much focus is put on the reflection to minimise anything less-than-perfect that may come from the more complicated effect though.
Make sure someone bumps the car up and down to make it looks like it's actually moving.
My 2 cents...!
Posted 10 September 2010 - 10:17 PM
Posted 26 September 2010 - 10:07 PM
This is some wacky green screen stuff. Shot entirely out doors at the Brownhoist Building and around Cleveland. Worries about reflections on the truck from the green screen were quickly replaced by more practical concerns. The wind got a bit stronger than expected, and the sun came around the corner of the building sooner than expected! So we regrouped and made it through the shoot with a lot of experimental imagery. For example, the building is covered in ivy on the east side, and in the afternoon we shot against that ivy and I partially chroma-keyed it out in Final Cut Express. Luckily the camera was rolling when the seamless paper billowed out on a strong wind gust, and that serendipitous moment allowed for the more light-hearted finale to the video.
In the editing room and with the short deadline in front of me--and having never done green screen or edited in Final Cut Express--I was really in trouble. The troubles that arose during shooting at first were nightmares for me, but eventually I had to embrace them and accept that I would not--at my skill level-- be able to properly correct them. So I went with it and came up with a playful nod to the green screen process, and a fun music video for the band and all to see. Please check it out on my You Tube page: JerMannski and play the Hey Mavis "Red Light" music video.
When I first asked band leader Ed Caner for his thoughts on what the video should look like, he said he loved the movie Airplane, when out the back window of the car the scene started with your normal traffic action but soon deteriorated to indians and calvary riding horses along behind the car! So we had planned on some fun shots, but I never expected such an "out there" result as I came up with.
It was commissioned for the 2010 Ingenuity Festival, Cleveland, Ohio, as part of "Rock That Spot," curated by Cynthia Penter.
Thanks to my filmmaker friends and the folks on the Cinematography.com forum for their advice on shooting green screen. Sorry I went against most of their recommendations!
Learning FCE under the gun was not fun, but all in all this project was blast!
Edited by Jerry Mann, 26 September 2010 - 10:10 PM.