The Art of the Fix: Visual Effects & Computer Animation
Published on Jan 9, 2014 by Christine Janesko
Artists and technicians who work in sound for film, photography, filmmaking, and recording all know one thing to be true: almost nothing comes out flawless. To create that ‘perfect’ moment often requires some altering of reality – also known as post-production.
In the fourth blog post for our Art of the Fix series, we talked to Computer Animation Course Director and experienced visual effects artist Joseph Brandibas about some of the more common fixes in the visual effects world.
Modern audiences are aware that many of the effects they see in films are computer generated and layered over much more ordinary scenes. In Jurassic Park, for instance, we realize that the actors aren’t really running from dinosaurs. While audiences understand about effects that are added in, they don’t always realize that things are also taken out of scenes.
Computer Animation Course Director Joseph Brandibas offers several examples of scenarios in which visual effects artists might delete images from scenes:
Rigs and Safety Lines
“Actors on films, a lot of times, you’ll never know it, but they’ll have safety lines – even if [they’re] just walking across the street. If there’s a car driving down the street, they have a safety line in case the car goes out of control or something,” says Brandibas. “You have to paint out the lines.” Artists not only have to remove safety lines, they may also have to remove safety personnel at the end of the line, along with any shadow that person might cast. To do this, post-production artists typically use a compositing software package called Nuke, says Brandibas.
Actors doing super-human aerial acrobatics wear what’s called a rig – also a challenge for visual effects artists. “Your superhero jumping up in the air is going to have a wire rig to pull him up, so you’ve got to remove all that. If he’s on a blue screen, it’s a little easier. It’s easy to map that out. He’ll have the harness, and sometimes it’s a thick harness, and so you have to completely recreate his body as well,” says Brandibas. “That’s a lot of paint.”
Moving Objects vs. Stationary Objects
Once an object or a person is deleted from a scene, the background has to be replaced. “If you’re lucky, as the sequence plays, whatever you’re pulling out is moving. And so you can find what was behind it, and you can clone from previous frames to fill it in,” says Brandibas. “We’ll get boom mics that accidentally get put in the shot, and so you paint those out. Those are fairly easy because they’re generally moving around, but every once in a while, they’ll have a light rig that gets stuck in [the frame] and it’s not moving. And you have to basically just look and see what’s there and paint it out.”
One of the more difficult fixes is removing a person passing in front of a building or car that needs to be in the scene: “Say there’s somebody walking down the street and they need that person removed, and a car goes behind that person. You have to remove the person, but the car’s still moving. So then you’re doing a lot of cloning from previous frames but then the car’s going to have reflections on it and maybe that person’s in the reflection of the car as it goes by,” explains Brandibas. “You’re constantly looking at every level of how that exists in the scene and how you can remove it. It’s not just painting that [person] out, [he] casts a shadow; there’s lots of variables that determine what you have to remove.”
There are countless other examples, says Brandibas, who worked as a digital artist on Southland Tales. In that film, artists had to add computer-generated buildings over a background that was basically a construction site. In this case, Brandibas use a technique called rotoscoping to select part of the foreground image he wanted to keep.
“We were able to just remove the construction site, but the problem was there were trees in front of it. And so we had to roto all the trees and the leaves and all that stuff because we were putting a CG building in behind the trees,” says Brandibas. Once the buildings were combined with the trees, Brandibas and the other artists actually had to match the grain of the film, the color balance, and the focal length of the original camera shot so the buildings looked like they were part of the scene.
“It’s literally a case-by-case basis when you do this stuff,” says Brandibas. How much is ‘fixed’ within films sometimes depends on the schedule of the film, the budget of the film, and how major or minor the problem is. “On your big budget movies, if the compositor does his or her job right, you’ll never know anything was done.”