VFX - Hollywood Lexicon

VFX

VFX stands for visual effects. The term applies to all post production techniques that create frame images which could not be captured by a single live camera shot because of physical or financial limitations. Although early filmmakers pioneered effects comparable to those of VFX, the techniques that inspired the term VFX were developed for digital filmmaking.

VFX’s history has involved the pairing of artistic imagination with computing power to make science fiction and fantasy the leading box office genres of the last three decades. Its pioneering is associated with such films as “Star Wars“ (1977), “Raiders of the Lost Ark” (1981), “The Abyss” (1989), “Jurassic Park” (1993), “Toy Story” (1995) and the “The Matrix” (1999). VFX pioneers include Industrial Light and Magic, Pixar, Weta Digital, Moving Picture Company and Framestore.

Chroma Keying

Before VFX, combining images of different shots into a single frame—a process called “compositing”—was accomplished by double exposure. Chroma keying (chroma meaning pure color) not only enables the combining of camera images into a single frame, but the combining of camera images with computer graphics.

Most often the process involves filming actors before a solid color screen, then replacing the screen’s pure color with a background image that frame-to-frame can be stationary or dynamic. Green and blue have been the colors commonly used for chroma keying screens because they contrast most with the yellows, reds and browns of human flesh.

Chroma keying enables scenes to be set in any location without the costs of filming on location, or in imaginary locales created by matte painting. Moreover, actors and crews enjoy the sound and lighting advantages of a studio.

Matte Painting

VFX matte paintings, which are settings created by artists, are graphically designed, not painted. As happened when commercial art transitioned to graphic art, matte painting saw its artists trade their brushes for Photoshop.

Pre-digital matte painters usually painted on glass, especially when their paintings were to be composited with dynamic images. Examples include the edge of a forest from which we see the Emerald City looming up from a field in “The Wizard of Oz” (1939); Edwardian London beneath a flying Mary Poppins in “Mary Poppins” (1964); and an enormous warehouse full of stacked nondescript boxes in “Raiders of the Lost Ark” (1981).

At Disney, animators developed a process that approximated 3D. Several glass matte paintings of tree tops led to a cottage in a clearing at night.The matte paintings were mounted at intervals in a cylinder through which the camera slowly zoomed. Each wave of tree tops would finally pass outside the field of view until the FOV was monopolized by the cottage. The one glitch was that, like the trees and cottage, the moon behind the cottage grew in size. The process would be modified to enable a sky matte painting to recede in synch with the camera zoom.

With Photoshop came the capability to import, combine, overlay, resize, draw, reshape, recolor, tint, shade—in sum, manipulate at will—digitized images, which could be anything photographical. Dynamic camera images, now also digital, could be composited readily with digital matte paintings delivering a more realistic, complex and realistic scenes for less money than pre-FXM processes. The next advancement in FXM realism would be software that could deliver 3D graphic images.

CGI Modeling and Compositing

Before VFX digital revolution, filmmakers employed stop motion photography to animate physical objects. The process involved moving a model’s parts in small increments and shooting the model after each increment. Models could be manipulated because they were made of clay or their parts were jointed. Hollywood’s masters of stop motion were Willis O’Brien, noted for films such as “Lost World” (1925), “King Kong” (1933) and “Mighty Joe Young” (1949); and his protégé, Ray Harryhausen, noted for films such as “It Came from Beneath the Sea” (1955), “Jason and the Argonauts” (1963) and “Clash of the Titans” (1981). Stop motion was also employed for animated television shows such as “Rudolph the Red-Nosed Reindeer” (1964) and “Here Come Peter Cottontail” (1971).

CGI (computer generated-imagery) involves the creation of 3D models using specialized computer software that defines the object’s surface mathematically. CGI models can be created on computer or by importing and converting to 3D two dimensional digital images. Essentially the object’s surface is mapped by points in 3D space that, when connected by lines, create a digital mesh exhibiting various contours of a geometric shape, e.g., the triangle, the rectangle, etc. When first developed, algorithms not only dictated movement of the model’s parts, but how each of its mesh components are colored to simulate lighting, shadow, texture, reflections and visual influences consistent with its composited 2D setting.

Introduced largely by video games, CGI would go mainstream in motion pictures when models could be composited with camera images and/or other models to create a realistic 3D frames. Groundbreaking films included “Jurassic Park” (1992) and “Toy Story” (1993). CGI would achieve even greater 3D realism with “ray tracing,” a process that traces the rays of each light source in a frame to the surfaces of models point by point, and from each point to a pixel in the frame through which the ray would pass to reach an eye centrally focused on the frame. Today, the challenge is to identify films that don’t employ CGI.

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