VFX DIARY – PART 4: ADVICE FROM THE FIELD
3D World’s VFX Diary from VFX supervisor Stephan Fleet dives into specific insights from production, including using previs on set and shooting greenscreen
This issue Stephan Fleet dives into some of the most important parts of the production process
Over three issues of 3D World visual effects supervisor Stephan Fleet, a veteran of the episodic television world, has guided us through the worlds of pre-production, shooting and postproduction. It’s a rare insight into the world of television VFX, where fast turnarounds are required from production, and high quality demanded by audiences.
Now Fleet looks into some very important aspects of the production process that have become crucial in almost all television shows that require visual effects: previs and greenscreen shooting. Specifically, Fleet’s discussion of previs is not about how to create the actual content, but instead how to utilise it on set. Then, the visual effects supervisor examines what works and does not work when you need to shoot greenscreen. Proper Previs Practices The benefits of creating and using previs – and the related fields of techvis and postvis – are widely recognised; indeed, CG animatics are a fast way of working out action beats, planning stunts and for using as placeholders until final visual effects are completed. But how should you actually take advantage of previs during the shoot? Fleet says there are a couple of ways.
“If you are fortunate enough to have a union playback operator on your show, you can hand them the previs and they can show it on any monitor. They can even do fancy 50/50 mixes and live keys. In lieu of that,
I usually show it on my laptop – ipads are frustrating for looping footage.”
Fleet says if you do have techvis or previs planned ahead of time, bring it to the table, i.e. don’t be afraid to use it. “Oftentimes, on big greenscreen days, you will find a lot of people staring at you wondering what to do, where things go. Have answers and show them the previs!”
One thing Fleet’s experience has made him realise, however, is that many directors and crew members do not always like previs on the set. They may find it stifles ‘finding the shot’ or slows production down.
“Everyone has their own system,” says Fleet. “I stress that previs should be used as a roadmap, but it should be understood that it’s a tool and not a replacement for creativity. If things come up on the day that change things, you have to roll with it. You have to give actors the freedom to not be robots and you have to allow for directors to adjust things. Don’t box them into a technical hole.”
On Fleet’s current show, The Boys, he has occasionally carried out his own previs and techvis, sometimes mapping out where cranes and telehandlers or boom lifts would need to be placed on set, and previewing how wire moves for particular stunts
would be handled. “We had limited time and space, so I basically built the jigsaw puzzle on my computer, virtually, before building it in real life. I was surprised at how most of our shoots went almost exactly as planned! And just how close stuff got to the real deal.”
“I have this theory that on any given day, 50 things will go wrong on set that you will have to overcome,” adds Fleet. “I look at all these tools, like previs, as ways to eliminate things that will go wrong. So if previs can knock out 30 of those things, great, you only have to deal with 20 more!” Getting Great Greenscreens Greenscreen, and bluescreen, shoots are a major factor in visual effects production, yet the plates achieved from shooting on them tend to vary wildly. A number of factors are the cause: from the location (in a studio, or at an outside location), to the time allowed for proper setup, to the lighting approach and then the shoot itself. Fleet is here to offer his advice for the best greenscreen shooting practices.
But first, the visual effects supervisor admits that “I’m that guy who hates greenscreen. I am of the opinion that you should do as little as possible to alter a piece of footage. That’s what keeps things as ‘real’ or ‘grounded’ as possible, to use some modern buzzwords. Now, as little as possible might actually mean a full greenscreen stage. But, for me, that is a last resort.”
What Fleet is suggesting here is not that you should never use greenscreen, but he is conscious that although greenscreen footage can look great, it is often burdened by a lack of time to achieve suitable lighting. “Greenscreen days are often ‘rain cover’ days,” he says. “Or, they’re just designed to make a production’s life easier. That’s not the kind of show I want to make. I don’t want to do driving stuff on a greenscreen because it’s ‘easier,’ I want to do what will make the best show, fitting the tone and style therein.”
Still, Fleet notes that shooting on greenscreen is unavoidable, and the best start to getting good plates is via tests. “Do daytime and nighttime tests, send them to your facility of choice, and find an IRE (the waveform measure) that pulls the best key. I use the Waveform/histogram method for exposure. Most shows can turn on one or the other on their monitors, so speaking in IRE makes sense to me.”
“As a general rule of thumb,” continues Fleet, “I’ve found that the screen should be about 55IRE (half-way up) for nighttime stuff, and around 60IRE for daytime stuff. Or, if you are going relative to the actor’s exposure, about at key for nighttime and about a half-stop over key for daytime.”
Fleet says these technical aspects of shooting greenscreen do tend to get overlooked on set these days, with screens often being uneven and exposure ‘all over the place’. “If you go much below 50IRE, you will run into some serious noise issues. But a DP might say they don’t have enough light – that’s a thing! – to bring it up. Tough. You have to find a way.”
Meanwhile, Fleet notes that the light colour temperature should always match your camera colour temperature, or be close to it. And he has some specific notes
“i look At All these tools, like previs, As ways to eliminate things that will go wrong on set” Stephan Fleet, visual effects supervisor
about the camera settings, too. “I tend to prefer the f-stop to be opened up more than closed down, as this eliminates more of the wrinkles in the greenscreen. That being said, seldom are things ideal. It could make it really hard for the focus puller to grab focus, or, if you are shooting anamorphic, focus pulls breathe really bad and can lead to worse problems. With anamorphic, I recommend sticking around an f4. But try not to go too high up – if things get super sharp and you start seeing dirt on the lens, it can then lead to a whole different world of problems.”
In terms of the greenscreen shoot, Fleet recommends shooting daylight exteriors outdoors if possible. “Make sure you angle the screen and shoot at the right time so the sun matches. Get detailed with the grips. Make sure they cover frames and lower them to the ground. Make sure you know how much greenscreen you need. But always confer with the DP, don’t go around the DP unless you have a friendly relationship and he or she is cool with it!”
There’s another factor with shooting greenscreen, and that’s actors. One of the obvious challenges is that actors (and the entire crew) have to imagine a world beyond the screen, plus work in large blue or green sets all day. Which means, says Fleet, you need to give the actors and crew room to breathe and be creative.
“If you have previs,” notes the VFX supervisor, “and it’s cool with the director, feel free to show the actors. But again, make sure they know you’re not boxing them in. If actors have ideas, do not, I repeat, do not shoot them down immediately if their ideas don’t fit into your technical document. Find a way to make it work for both of you. After all, their performance is the number one most important thing you are trying to capture. Their expressions, their believability are what will make a good shot great. Not just a better greenscreen key.” Where to see Fleet’s Work next The Boys is Fleet’s current show; it’s an Amazon series based on the comic book of the same name, and executive produced by Eric Kripke, Seth Rogen and Evan Goldberg. Production for the series, set to stream in 2019, took place in Toronto.
“The Boys is a big-ticket show,” says Fleet. “It’s not even a show really, it’s some kind of super-sized, feature-quality beast that will be unleashed in eight one-hour instalments sometime this year. Also if Jack Ryan is any indication, your Amazon boxes will probably be plastered in Boys advertising, along with every bus and billboard on the planet. It’s very exciting!”