Green Screen!

I've never been able to make a green screen really work. I'm looking into buying a new green screen and I was wondering if someone could tell me whether to get foamed back fabric, (http://cgi.ebay.com/eBayISAPI.dll?Vi...3536 629&rd=1)
polyester,
(http://cgi.ebay.com/eBayISAPI.dll?Vi...2413 111&rd=1)
or thick flannel
(http://cgi.ebay.com/eBayISAPI.dll?Vi...3268 979&rd=1)

also what is the best way to light a green screen? I just purchased a light kit that comes with umbrellas. If I get a colapsable fabric green screen should I put a light behind the green screen so it shines through? Or what?

Thanks so much,
Jacob

[celycom]

I've been lighting for and shooting green and blue screen for years, and I prefer foam-backed material, hands down. It really is less likely to develop bad creases if you take care, and DO NOT fold it the same way each time you put it away. Matter of fact, if possible, you should roll it up, then gently fold it (if you must) before storing it in a ROOMY bag.

The secret to shooting good chromakey, UltaMatte or any kind of key is to evenly light the background. You simply use soft lights to evenly cover as much of the screen as you'll use in your shot. Umbrellas are indeed useful, but it is harder to control all the spill light they generate.

I have a regular gig shooting HiDef and DigiBeta green screen of a couple of major NASCAR drivers for TV commercials. I use a 12x12 foam green screen, lit by 2 Lowel softlights, using only 1 1k globe in each soft light. I place them about 10 feet from the screen, about 7 feet high, on the right and left side. My subject is just a foot or two closer to the camera, and is lit with softboxes from the front, a single 650w backlight (placed behind and above the greenscreen) and 2 200 watt edge lights on either side of the background. The back light and edge lights (kickers) are diffused with Lee 216. I also add Bastard Amber gel to these three lights just to minimize any residual green bounce from the background. If you are using blue screen, you might use 1/4 CTO (color temperature orange) instead of the Bastard Amber. Get a Rosco, Lee or GAM gel swatch book from any lighting supplier and familiarize yourself with the colors if you aren't already.

Keep one thing in mind. It really doesn't matter how you light the foreground subject, as long as you can separate it from the background. For instance, on a kids' show I once did, we had numerous fantasy situations we would put the characters in... I would always try to replicate the lighting effects from the fantasy background on the subject in the foreground. When we had a fire truck parked behind and to the left of our actor, for instance, I used a rotating red light on that side of the subject. When we had a kitchen set with strong sunlight coming from the other side, I matched the angle of the light with a strong 2k, and even left a deliberate shadow on the floor to match the imaginary set. Get it?

There is no reason your foreground lighting has to be flat or unimaginative, as long as you keep the neccessary separation from the background going. The secret is to experiment as much as possible BEFORE you get into a high pressure situation. Enjoy yourself!

[Josh]

Celycom offers excellent advice. To make sure lighting is even, you can use the zebra function on your camcorder- try to get the lighting so that in two or three clicks, the greenscreen goes from full zebra to no zebra. That's an evenly lit screen! And it will show you where the hotspots are without guessing.

This and many other tips on the DV Enlightenment DVD (click link in my sig below) which contains a whole section on lighting greenscreen.

Check out Reflecmedia.com for chromakey solutions that do not need lighting

I agree http://www.reflecmedia.com

[Josh]

Do you own the Reflecmedia.com system? Would like to hear comments from an owner.

[littleone]

Check out www.iphotovideo.com for
Reality sets to use for after you shoot your chroma video.
Regards
Benn Salis

[LS3D]

Reflecmedia's Chromatte is great, but at $30 (US) per square foot, plus light rings, ctrls, etc it adds up quick. A two camera shoot with a decent key area comes in at about $13K. Then you still got to light the talent, etc. Might as well through in the tracking system that the BBC developed together with Chromatte and really do it up (it is the fastest tracking technology I have ever seen)

I have worked with multi million dollar realtime virtual sets (Orad, SGI, Ultillmatte, etc) in my career, and continue to model 3D environments, but now my mission is to implement a set design for a client using prosumer tools & modest budgets, much like I imagine many of the visitors here are doing.

I have tossed Chromatte off the budget in favor of experimenting with Ultra, and possibly a Matrox RTX. With the show format running 20 - 40 minutes I am concerned that rendering in Ultra could be a production bottleneck.

So any comments from Ultra & Matrox users are welcome, but what I am really after are good lighting tips, so thanks for the information above and elsewhere on the forum, and any other advice for lighting a 16X16 foot chromakey "studio" in an industrial warehouse space.

Here is my budget keywall, it is only for tight shots, talking heads, seated at a (real) desk etc, so no transition to the floor like a pro cyclorama. I may implement a roll out key material for full body shots latter. Transparency is to show construction to builder, may also run photometric light plots/radiosity latterz.

Chroma basic wall design here.

I want to use fluorescent (cool) lighting, like videssence, although I may try to mix home depot outdoor lighting with a few pro lights and see if the color temps are even close. And so finally a question?

Should I avoid mixing incandescent and flouro lights? My client has a few crappy incandescent and I am tempted to toss em.

Any guestimation of a decent lighting package, specs and cost also of great value.

I hope I can post some work in progress and share my experience here as this project is green-lighted and I expect things to happen pretty quickly.

Kind regards,

-Shea

[TheDoc]

I have been using Ultra since it came out - Frankly, I think it's the cat's meow where chroma keying is concerned. But, like everything else in video, lighting is real important. Some hints from my experience with Ultra:

1. You can use both fluorescent & incandescent lighting, but I would do this using the fluorescent only to light the screen, and incandescent to light the talent with the talent standing about 6-8 feet (or more) from the screen.

2. The screen should be lit evenly. Ultra is pretty forgiving, & will key the screen even with shadows & uneven light, but your best results will be with even lighting. I place two lights on either side of the screen, each about 3 feet away. Lowel Tota lights, with or without umbrellas work well. Use the Zebra function to check for the eveness of the lighting. I light my screen to an IRE of about 80-85 (higher if needed), and the skin of the talent to about 70.

3. Remember to pre-roll a few seconds of the lit screen without the talent - this allows you to set the key in a single click.

4. Aside from using Ultra, I also use DV Rack from Serious Magic. This allows me to analyze my lighting very accurately & quickly, as well as record to the hard drive of my laptop.

5. You can't go wrong with any one of the Lowel DVcreators Kits

Hope this helps.

[LS3D]

Hey Doc,

Thanks for the info, I'm taking notes & adding a light meter to the order. I think I will go with a Lowel DV Pro 55 Tungsten 5 Light Kit for the "talent" and some flavor of dimmable flourescents (4 or 5) for the key. Dimmable because I expect these will be mounted to the grid & I will not be able to move them as much. I also like putting kickers on the floor and will try some cheaper tubes there.

I just ran some radiosity test with photometric lights in 3DS Max, the results may be interesting to some. Clearly shows why a radius is required for wide shots.

Rad Test Here

-S

[Digi-Man]

I've also been shooting Green screen for years and foam-backed fabric is the way to go. If you need to buy some, goto:

www.eefx.com

They are the cheapest on the net and can custom make any size you need in-house.

Happy Keying,

Digi-Man
Visual Effects Soup

[flashfreaker]

I recently purchased the Lowel DV Pro 55 Tungsten 5 Light Kit as well, but I'd likle to use the two 500W V lights to evenly light a 6x9 green screen. Any advice on how to position the lights (distance, angle, door positions, etc) or should I use the lower wattage lights in the kit?

Thanks in advance!

[lumenbeing]

Originally Posted by Digi-Man

I've also been shooting Green screen for years and foam-backed fabric is the way to go. If you need to buy some, goto:

www.eefx.com

They are the cheapest on the net and can custom make any size you need in-house.

Happy Keying,

Digi-Man
Visual Effects Soup

Absolutely agree with you. We have one custom sewn and the quality and workmanship was excellence. Completely wrinkle free. We just used thumb tacks (one every 6 inches) to pin it to the wall. I get a great key every time using Keylight in After effects.

[robertd2d]

a colleague of mine pitch a very creative and cheap way to create a green screen. I don't know if it could work, but sounds ingenious. He said to get a linoleum and paint it with chroma keying colors. So that way, it's easy to roll in for break down, and easy to roll out for set up with no wrinkles!!! or whatever. But like I said, we've been talking about it for awhile but haven't tried it. what do you guys reckon?

[Shep2112]

Would it be totally smooth or textured? Would it be shiny? I would think it'd be tough to keep the paint on there with constant rolling and unrolling, if the material is designed to ward off stains and such. Just a thought.

Eric