How Visual Effects Work in Film: A Guide to the 4 Types of VFX

Visual effects allow filmmakers to create breathtaking imaginary universes and achieve stunts that would be impossible to film in the real world—but visual effects aren't exclusive to blockbuster feature films. Filmmakers also use subtle visual effects in more grounded films in order to tell their stories more effectively.

In filmmaking, visual effects (VFX) is the creation or manipulation of any on-screen imagery that does not physically exist in real life. VFX allows filmmakers to create environments, objects, creatures, and even people that would otherwise be impractical or impossible to film in the context of a live-action shot. VFX in film frequently involves the integration of live-action footage with computer-generated imagery (CGI).

The term “visual effects” is not interchangeable with the term “special effects” (SFX). Unlike VFX, SFX are achieved in real-time during filming; examples include pyrotechnics, fake rain, animatronics, and prosthetic makeup. All VFX are added after shooting in post-production.

Top visual effects studios are staffed with VFX supervisors and teams of VFX artists who all have their own specialties. Most types of VFX fall into one or more of the following categories:

1. 1. CGI: Computer-generated imagery is the blanket term used to describe digitally-created VFX in film and television. These computer graphics can be 2D or 3D, but CGI is generally referenced when talking about 3D VFX. The most talked-about process in CGI is 3D modeling—the creation of a 3D representation of any object, surface, or living creature. CGI VFX are most apparent when artists use them to create something that doesn't exist, like a dragon or monster. But visual effects can also be more subtle; VFX artists can use VFX to fill a baseball stadium with a crowd of cheering fans or de-age an actor to make them appear younger, like Robert De Niro in The Irishman directed by Martin Scorsese.
2. 2. Compositing: Also called “chroma keying,” compositing is when VFX artists combine visual elements from separate origins to make it appear as though they are in the same place. This visual effect technique requires filming with a green screen or blue screen that compositors later replace with another element using compositing software in post-production. An early form of compositing achieved this effect with matte paintings—illustrations of landscapes or sets that were composited with live-action footage. One of the famous examples of a matte painting used as an optical composite is the Emerald City landscape in The Wizard of Oz.
3. 3. Motion capture: Often shorthanded as "mocap," motion capture is the process of digitally recording an actor's movements, then transferring those movements to a computer-generated 3D model. When this process includes recording an actor's facial expressions, it's often referred to specifically as “performance capture.” One common motion capture method involves placing an actor in a motion-capture suit covered in special markers that a camera can track (or in the case of performance capture, dots painted on the actor's face). The data captured by the cameras is then mapped onto a 3D skeleton model using motion capture software.

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