VFX From Inception To The Big Screen—PART 2: Post-Production
This post first appeared on Film Independent on February 18th, 2015.
Ever wonder what the process is to get fantastic effects onto the screen? Creating VFX is generally pretty complex, but here’s a distilled look at the basics, broken down by the production team of Scarecrow VFX: VFX supervisor Josh Bryer and VFX producer Melissa Brockman.
What happens once principal is wrapped and you’ve delivered plates (what we call the backgrounds you shot on set) to your VFX team? That is a topic that could merit many books worth of discussion, but here’s the most basic breakdown of some common stages of the vfx process and what you might expect to see during these stages.
Modeling This is the process of creating digital representations of the geometry of an object; think of it as defining the shape of something. Many times when reviewing a model, you’ll see it as a simple gray shaded object.
Texture/Lookdev This is where you define the color, textural detail and material properties of something. In other words, what makes that table look like wood, what does the wood grain pattern look like, how does it reflect light, etc. When reviewing lookdev, you may look at your static object spinning in place in a neutral lighting environment (a turntable), or you may just review it in context of the shots.
Rigging Especially important for characters, the rigging stage is where things are setup to move: skeletons, muscle, skin systems etc. This stage involves the creation of all the tools that artists are going to use later to drive the motion of objects. Seeing things from the point of the filmmaker, this stage will generally be transparent to you.
Tracking/Matchmove This process involves the creation of a virtual camera that matches the physical camera on set, and generally also recreates some of the basic objects from the set. It can also involve the creation of digital objects to line up with people and things that are moving through the plate. You generally won’t be reviewing product from this stage.
Animation You’ve got your object, you’ve defined its look, now here’s where we’re going to make it move. Using either traditional keyframe animation, motion capture data, or other methods, you’ll begin to see your effect moving in the context of your plate. Usually, when reviewing animation, you’ll see things as gray shaded objects on top of the plate, or with very simple textures applied for context.
FX This is another stage where motion is defined. However, this one focuses on creating motion that can’t be animated by hand. Complex physics like smoke, explosions and water are all created in the FX stage.
Matte Painting Evolved from traditional matte paintings that were done on glass and photographed in camera, digital matte painting allows for the creation of things like background replacements, set extensions, etc. Matte painting is a broad term that can really encompass a lot of techniques, but it has historically been used to refer to a two-dimensional painting placed in the background of a shot.
Lighting This is the first stage where your effects are beginning to be visually integrated into the plate. Using digital representations of lights and data that was captured on set, the lighting environment is recreated and the effects are made to look like they fit with the lighting photography. This is the first time you’ll begin to see things looking more “real.”
Compositing This is the final stage of the process; it is where the last bit of photo reality is brought to the effect. The process involves taking many layers of moving 2D imagery and layering them together so that it feels like the effects belong in the plate. Compositing is truly the stage that brings it all together, and is where you’ll begin to really feel like your effects look less raw and more polished.
DI Just like the rest of the shots in your film, your VFX will likely end up in DI for color grading. Though this process generally happens at the end of post, it has ramifications for the VFX process that must be dealt with earlier in the process.Make sure everyone is working in the correct color space—your plates will be given to your vendors in a specific color space. Make sure it’s uniform across plates and work with your DI facility to make sure that the pulls are being done in a way that gives them enough latitude during color correction. Most DI facilities will have a house-specific color lookup table (LUT) for different color spaces and source material. Likewise, during your pre-grade, they might have created a custom LUT based on a specific look you’re trying to hit. Make sure to show the LUT to your VFX vendors as early as possible, as the LUT can change the final look greatly.
On an end note, now that you have some understanding of the basics of a VFX process, here are some things to think about as you embark on your filmmaking journey through the land of VFX:
Be aware of the fact that your decisions have consequences, both from a cost and a scheduling standpoint. Decisions that you make at the beginning of the process (in lookdev, for instance) can be very difficult to undo or change later in the game.
You’re not going to see everything immediately. Sometimes, during the early stages of VFX review, things are going to look really incomplete and this can be very jarring. Do not fear though, you have to build the foundation for your house first, and things will continue to progress. A good VFX supervisor will always walk you through a shot and let you know what they need feedback on and where they are in the process.
For someone who hasn’t worked with VFX before, the process can seem like it takes a long time and progress can feel very non-linear. There is a lot going on behind the scenes that you’re not seeing, and sometimes it feels like 75% of your progress is made in the last 20% of your schedule.
There you have it, the 30,000-foot view of what to expect from the VFX process. Now, on to the other 119 minutes of your movie!
Josh Bryer and Melissa Brockman / Scarecrow VFX