There are a variety of "Behind the Scenes" videos from major VFX movies that show the actors interacting with someone dressed in an outfit reminiscent of The Riddler from the 1960s Batman series. Through a magical process, the green suit, green stick and green screen in the last frame disappear.
In the minds of many, the green suit is a magical solution that makes things disappear at the push of a button. Unfortunately, this isn't just limited to newbies in the industry, but also circulates among seasoned veterans of the industry. The reality is that the behind-the-scenes clips often hide weeks or even months of tedious work from a wide variety of VFX departments, from composers and rotopaint artists to matchmovers, 3D modelers and animators.
What is going on here? Is that something indie filmmakers can jump on board with?
Well yes and no. Yes, it's something that is increasingly available to all filmmakers, but all too often there is also a gross underestimation of the work involved.
So why green, why blue and what are they doing?
Last question first: blue / green screen and all variants (sticks, suits etc) allow the VFX team to drill holes in the footage. Black holes that hopefully can be filled with something cool.
So the main choices depend on the color of the foreground – someone in a blue suit will likely want to be photographed on a green screen, while Kermit the Frog should be shot on a blue screen (gets tricky when Gonzo and Kermit hang out together).
Is it easy to get rid of someone in a green suit?
Again, the green or blue is just to make a hole, a hole that can be filled with something else. How easy it is to make an exact hole (or matte) depends on how even the green or blue color is.
Things that make this difficult are shadows, inconsistent lighting, inconsistent hues on the screen, wrinkles, and so on. Even with background green screens, you get these often. You are guaranteed to get all of these things with a suit.
Also of great importance is the difference between the screen and the background. I once had to type a goalkeeper in green from a green screen – only I could type it – I have to draw the mats by hand (more on that later).
So if it's not just one click, what are the VFX people doing? Well, the people who make the green disappear are the composers (i.e. they put multiple images together into one). You will basically be using different keyers for the different shades and animation masks, which can be rotoscopes with great detail (like little white cartoon characters that fit the cast exactly), or they can be loose and soft to hold the key for the dark green to mix with the key for the light green. As the number of manual adjustments increases, the value of a greenscreen / suit or prop decreases. Still nobody wants to animate mats for hair by hand!
But either way, we've only made one hole so far!
So if I put a robot over the man in the green suit, does it have to be green?
No, if the CGI robot covers the original performer, it doesn't matter what color it is. The gray mocap suits from District 9 are a very good example. You don't have to make a hole, the alien goes to the top and any little parts of the actor that stick out can easily be mended.
On the other hand, when another actor stands in front of the substitute actor? Then you want a hole, a hole that goes around the actor, so hopefully the CGI will fit right between the foreground actor and the background.
Perhaps you don't need a replacement at all – or you can include a replacement for a different setting for the animators' reference. This is the approach we used for our upcoming Broken Toy promo. Look again at the division in District 9 and you will see that substitute artists were not always used.
In the above shot from our “Mikkei Toy Commercial” promo for “Broken Toy” the most difficult problem was restoring the foreground grass and lens flare
So this is really the missing key to most people's understanding of the process. If you do, you will be much better equipped to start planning VFX. Once we've made a hole, anything that isn't filled with our new element (CGI, a background image, or whatever) needs to be painted back with the original material. It could be super simple, like a white wall, more difficult like a wall with a bush in front of it, or insanely difficult like the familiar face of the leading actors in close-up while they brush their hair during a rack of focus.
So the point is – the difficulty in removing something from the foreground is largely due to the complexity of replacing what was obscured by that thing. It could mean creating a full CGI version of the main cast, set, and potted plant and then recreating camera movement in the computer and then shuffling it all together, or it could be something as simple as a still image from another part of the Take footage and with it. Until you see the recording, you can't actually quote it.
An example of a pretty tricky recording I've been working on is Matteo Garrones Pinocchio under VFX supervisor Theo Demiris at One of Us VFX. If you look into this for 20 seconds Breakdown roll You can see where a green crash helmet and nose rig had to be replaced with a partial CG head and nose. The background needed to be restored (as Pinocchio's head is smaller than the crash helmet, part of Federico Ielpi's face and body), even since the nose rig had shifted from his last CG nose. I was fortunate enough to get much of this painting from some very talented prep artists (folks who do animated digital paint, unsung heroes of the VFX world, that's right), a CG head, a nose, and birds, and then got I did my job of sewing everything together.
When working on an indie project, I would certainly have avoided this angle and would have just made the nose visible from the side in front of the wall.
Work in progress shot from our "Mikkei Toy Commercial", promo for "Broken Toy"
Without further ado, here are some tips for the indie filmmaker:
- Make your CG character bigger than the actor – so that they cover him completely.
- Make it easy to replace your backgrounds: think walls or open skies.
- Don't use smoke – if you need smoke add the smoke in the post so it affects the live action and CG consistently. Painting back in smoke is painful, believe me.
- Avoid recreating tricky elements like actors, trees and bushes (lots of complex shapes moving at different speeds and distances from the camera), water, reflective surfaces, moving curtains, and the like.
- Keep your deputy as close to the CG as possible – easier to upgrade a practical costume with a few selected CG elements (like tentacles) than to create a full CG character.
- Shoot lots of references: clean the panels (i.e. have everyone clear the set and take up the empty set with your final lighting). Capture stills of all background set items, props, costumes and performers (with final makeup). You never know what can help you later.
- Have a VFX supervisor on the set. Even if you are not a professional VFX supervisor (which may not be possible with a low budget film), you should at least hire a professional compositor, matchmove artist, or 3D generalist to step up in supervision. Many VFX artists want to switch to supervision and are looking for experience on the set.
- Prepare for the long hall: the VFX work takes a lot of time and happens after your offline editing is locked. So take this extra time into account in your distribution plan.
- Cut out unnecessary VFX. In the original Ghostbusters script, the Stay Puff Marshmallow Man was supposed to rise and step out of the water in Hudson Bay. The Special FX team asked if this was really necessary and indicated that it would get super expensive. You cut the recordings from the script without loss for the final film.
About Daniel Mark Miller
Director Daniel Mark Miller is a British-Iranian VFX artist, screenwriter and filmmaker.
Daniel started writing at a young age and has always had a taste for the strange, the fantastic and the outsider. Daniel continued to write and work independently for over 10 years as a professional digital compositor for important feature films and TV shows such as Baby Driver, The Crown, Good Omens, Pinocchio, Giri Haji and Morbius.
He recently won Best Short Screenplay for "Broken Toy" at the New Renaissance Film Festival 2020 and is currently working on a promotion for the short film.