Advertisement
Current Issue
August 2014
Issue: July 1, 2008

GREENSCREEN TECHNIQUES

By: Randi Altman
The art of greenscreen has become demystified in recent years thanks to the accessibility of professional tools at affordable prices. But access to good tools alone doesn't convey command of the nuances that working with a key demands. Angles, lighting and experience make all the difference.

THE DIFFERENCE A YEAR MAKES

At Venice, CA's Fish Eggs (www.fisheggs.tv), broadcast design comprises about 80 percent of the studio's work. From creating logos to main titles to simple graphics to lower thirds — if it's part of a broadcast package, they do it. The other 20 percent of their time is spent on spots, film titles, industrials and some trailer work.

Founder/creative director Chris Roe says greenscreen is now an important part of his studio's business, but that even a year ago — considering that they were not "experts" or visual effects people — greenscreen was more of a rarity. "A year ago I'd have to have somebody else make sure everything was working out properly. It was out of our realm," he says.

Roe points to affordable, professional tools, as well as Moore's Law as the main reason for the change. "We use Adobe After Effects for compositing with Keylight plug-ins, and the processing power of the computers and storage space makes it easy to shoot and or take in footage." Fish Eggs uses greenscreen about 20 percent of the time in its work.

Roe admits that in the past he thought of greenscreen as a big-ticket item. "Now it's much more commonplace in our workflow. It was always a flag for us to add a little extra safety budget because there were always variables we weren't sure about. Now it's easier, partially because of the software and computers and partially because of the availability of the people who know how to work with it."

With more experience there is less of an intimidation factor, he says, pointing out that Fish Eggs' greenscreen process is not that complicated. "You key it out, and there are only a few basic rules on how to keep it evenly lit," he says, admitting they aren't experts but as greenscreen becomes more a part of their every-day work, it gets easier.

And some of that work includes the ABC dance competition show Dance Machine. They used greenscreen on two different elements that are part of the game. The producers wanted to introduce different categories of dancing — disco, hip-hop and '80s.  "Instead of putting a title up that says disco, the executive producer had an idea to show two people dancing and give it sort of an 'iPod' treatment."

They couldn't find stock footage to work with — their first choice — so they ended up shooting the category stuff greenscreen. The other segment included the contestants going "nose to nose," like a boxing poster shot. This was a still shoot with the contestants shot individually, "because we didn't know who they were going to be going up against during the show," explains Roe, who worked with the still photographer to make sure the lighting matched the lighting needed.

The client asked for the dancing to be in a silhouette, but not a pure silhouette because they wanted to keep some of the clothes information. This one was shot live action in high def with Fish Eggs directing the action. "They wanted some back-and-forth-type moves," describes Roe. "It was rear lit with smoke, so it had light streaming around the dancers. We told them it could be done naturally, but we would have a lot more control if it was shot on a greenscreen; we'd be able to change colors, add smoke and other elements, and as many light streaks as they wanted. If they shot it on a smokey-lit background not on greenscreen, we would basically be limited to how well it was shot at the time."

According to Roe, they shot it on HD "because they were concerned about quality if we were going to blow it up or move it around. HD is going to give us a cleaner image generally and, all things being equal, HD is going to give you more information to play with and be a little easier to key."

Another recent greenscreen project was for the open of the NBC show American Gladiators, which was shot in the "Gladiator Arena." Roe directed this HD shoot as well. The goal was to give these incredibly fit men and woman a glossy look — they were covered with Vaseline gel and shot on a rotating turntable in front of a greenscreen. "We created a background as well as titles that would go in front of them, as would smoke and light," describes Roe. This was for the main title and on their stat pages — "You are going to go up against Wolf," and it shows that player's physical stats.

When the producers saw the contestants all greased up, they were a little nervous, shares Roe. "I kept telling them it was going to make the light really kick and pop and when we put the environment around them it will look good." And it did.

SEEING THE LIGHT


Santa Monica-based Elicit (www.elicitfx.com) opened less than a year ago centered around a Flame 2008 and featuring an expand-and-contract model. "I pre-qualify my clients' projects, see what their needs are and hire the best freelance artists to help accomplish that," explains creative director/senior Flame artist Les Umberger. "It helps keep our overhead low so we can work with today's modern budgets, which are shrinking."

It also allows him to get the best talent for the job. "Instead of keeping a bunch of generalists around and forcing them to do things they might not be good at, if I have a big particle job, I get the best CG particle guy I know. In turn the client gets the best product for the best price."

Commercials and music videos are the main focus at Elicit with spot work taking up 75 percent of their time. "We work with greenscreen all the time," says Umberger. "It's almost become one of those things that is expected. Very rarely now is something heavily composited in the live action realm that does not require at least one blue- or greenscreen shot in it."

He also feels that having affordable tools readily accessible to the masses is having an effect on quality. "One thing that I've been noticing a lot of, especially among people who are fairly new to the business, or guys who are mainly digital cinematographers working in HD or on the Red camera: the greenscreen quality is starting to lessen."

And while he can fix the lighting in post, it's not the way he prefers to work. "If it's not exactly lit or angled right, we can deal with that, so it's become a little less important, but as far as selling a composite as a whole, lighting will make or break whether or not this person or element is going to fit within the background plate. It's really paramount to make sure the highlights and the key light are coming from the same direction and have the same temperature."

A big greenscreen job for Elicit was a high definition stereoscopic music video for Missy Elliot called Ching-A-Ling. The two-day shoot, shot by Dave Meyers for @Radical Media, included a white cyc in addition to a greenscreen cyc. It was shot with Pace cameras. The fantasy-themed piece features the Grammy-winner in a variety of environments.

One shows her with eye candy motion graphics in the background. There is another that involved a large Norman Rockwell-ish matte painting and the singer on swing hanging from a big tree. The biggest one, according to Umberger, is called the Coin Room. "It's Missy and about six dancers dressed up in coin outfits in a room that is made up of giant gold coins —the dancers are hidden in the back wall and just pop off and dance around with Missy."

Another set-up had Missy and a male dancer doing a take-off on an interactive dancing game while in a very trippy environment. They are on a moving metal barge in the middle of space with these flying letters coming at them.

Did working in stereoscopic affect the way Elicit handled the project? "I didn't really change the way the greenscreens are dealt with," says Umberger, "although you are dealing with two separate lenses to two separate video feeds, so there is a color variance. Between the left eye and the right eye it would require us to go in and tweak the keys a little bit. One might be a little more yellow, one might be a little more magenta and it could be a minute difference but enough to affect what's keying. And with stereoscopic,  both eyes have to be so spot on that it was very important to keep the level of detail between the two eyes as similar as possible or the anomalies would be popping off the screen at people."

The video was shown at private screenings throughout the country and on MTV as an anaglyphic version — viewers picked up glasses at local music stores for viewing on television. In addition to the Flame, where most of their compositing is done, Elicit uses After Effects and Autodesk Combustion.
Umberger offers this tip: "If you are dealing with multiple people or things, it's much better to break your set up and key individual elements individually."

Umberger is a film advocate when it comes to pulling greenscreen. "Even if a job is shot on HD and we have the ability to shoot the greenscreen plates on film, I will do that. When you deal with greenscreen it boils down to the information that you have, and film captures the details so well, and there is no compression involved." He says this is where HD and a lot of the file-based formats start to fall apart because they are so highly compressed.

TAKE YOUR TIME

The NYC-based offshoot of London's Oscar-winning (Golden Compass) VFX studio, Framestore focuses mostly on commercial work, and VFX supervisor/lead Flame artist Murray Butler reports that about 40 percent of those projects include greenscreen.

When do they decide a composite might be best for the job? During the pitching process, says Butler. Sometimes before a director is even brought o the project, Framestore CFC (www.framestore-cfc.com) will recommend the best technique for the spot, but other things come into play, he says, like the director not being enamored with greenscreen. "If a director likes to work quickly and doesn't want to have to stop to position and light greenscreen, we can always rotoscope elements that need to be layered into the scene. Although it's more time consuming on our end, it will make for a much smoother shooting process, but fine details like hair or dust make it trickier. We just need to plan for these kind of things prior to the shoot because it's a more labor-intensive process."

It's this kind of knowledge that novices, or those who might own the right gear but not the right experience, might not be aware of. "It isn't as easy to get people who can light to match plates and prepare stuff in a technical way," says Butler. "It's easy enough to shoot greenscreen around people, but it will look a bit dodgy if it wasn't lit the same way or they haven't lit the greenscreen properly."

Proper production values take these kinds of jobs to a whole new level. "It's really not just about the greenscreen," he says, "it's about whatever technique you are using for layering imagery or compositing. If people can match angles and match lighting, that's what makes it look really good, whether or not you use greenscreen. It is a kind of art form."

He offers this tip about lighting: "I'm always keen to remind people, especially after shooting exteriors and then going off to shoot interiors, you need a lot of space lights [which can be costly] to simulate daylight. If you don't have that, it can look very 'studio bound.' The other solution is to shoot people outside in an exterior location at the same time of day with greenscreen behind them… that could look really good."

While Butler is a working director, for these projects he's on set in visual effects supervisor capacity only. He says it's very rare to get a DP who isn't savvy in the art of lighting greenscreen, "but if I see something that isn't right, like an angle or a lighting set-up, I will talk to the director and DP."

Butler brought his experience on set recently for a recent 35mm shoot for Autotrader out of agency Doner. The :30 spot features a giant man walking in LA and going  from car showroom to car showroom trying to find the best deal. It's all greenscreen.

"It's crucial that the lighting matches, from the exteriors to the greenscreen" he explains. "We make sure that we log all the camera information on location so in the studio we can match lenses, tilt and camera height. And when the giant is walking between buildings, we have green boxes to represent the skyscrapers. This allow us to interact and cast shadows on things."

One shot in the spot that wasn't "greenscreen" is where a hand comes through a window to grab a car. "That was shot on gray because we didn't want all the green spill out on the body," explains Butler. "When you get too close to greenscreen the bounce makes people's faces look weird, so you have to do it by hand and not use greenscreen." He emphasizes that knowing when and when not to use the technique is hugely important.

Another tip he offers is don't rush. "There is a tendency to try to cram a lot of shots in. Lighting and angle are key and it's worth taking the time to get it right." Butler uses a Linux-based Flame 2008 and calls on sparks, such as The Foundry's Keylight, to make everything look as real as possible.
 
A DIRECTOR'S PERSPECTIVE

Headquartered in New York City, with offices in Miami, Tampa and LA, Habana Avenue is a hybrid company, or as executive producer/director Steven J. Levy puts it, "a new adversary of the agency world." He explains that a lot of networks are directing their creative services in-houses without pulling in outside-represented directors. Habana provides production and post support and has been doing so for about five years.

Habana (www.habanaavenue.com) is a full-service production company working in television, film, commercials, corporate and live events work. In Tampa they offer Bungalow Post at Habana Avenue and they also work hand in hand with three outside post studios — Vidiots in NY, Outsider in Chicago and Mad Toybox in Charlotte — "but we start off as a creative company," he emphasizes.

Almost all of the work Habana does for network sports coverage has an element of blue- or greenscreen. "There is always a transition to their bread and butter, which is sports." He says the networks could use an expected transition, a jump cut, to get to live action and go full screen, "but it's more creative to figure out ways to get there through the production design and art direction."

Like the others in this piece, Levy also believes that greenscreen has become more accessible to all. "There was a time when you were doing a key, you would have to have a post supervisor with you to guarantee it could be pulled off, but we haven't had a post supervisor on a shoot in probably eight years."
Also, like the others, Levy reports that lighting is the most critical aspect of greenscreen work. "Lighting and distance," he says, "making sure the light on your backdrop is even, that the stop is as close as it can be across the whole background, the whole key, the whole greenscreen area."

You start running into problems when there are exposure differences and/or shadows. "Then it's always preferable to pull your subject as far from the greenscreen as possible, but this can be cost prohibitive, depending on how big your set is," he says. "Lighting is an easy thing to fix while you are on-set and a harder thing to fix if you send it on in to post and it's not correct."

Habana recently developed two high-profile greenscreen ventures for NASCAR related projects; the first interview was a spot out of Goodby Silverstein, SF featuring drivers. The following featured the band Aerosmith, who re-tracked "Back in the Saddle" to reference NASCAR, during a concert at the MGM Grand in Las Vegas. The band, who was shot in front of a giant, pre-hung greenscreen, did a run-through of the song so the finished product would look like they were doing the concert in front of a huge TV playing race footage — from close-ups of the checkered flag to cars racing by to victory lane.

"Then we re-shot the song a second time with a full audience in a concert environment, and we had the choice when we cut it up  — because there are so many different races — to either insert footage or to have the live concert footage," explains Levy. "The NASCAR open, used for about 42 races, is probably going to be the most aired open ever, or at least for us." The footage is also being used for bumpers, opens, closes, in and out of commercials and promos. Compositing was done at ESPN on an Avid Symphony Nitris.