[custom_adv] It gives filmmakers greater control, and allows many effects to be accomplished more safely and convincingly and—as technology improves—at lower costs. As a result, many optical and mechanical effects techniques have been superseded by CGI. [custom_adv] The illusions or tricks of the eye used in the film, television, theatre, video game, and simulator industries to simulate the imagined events in a story or virtual world are traditionally called special effects (often abbreviated as SFX, SPFX, or simply FX). [custom_adv] Special effects are traditionally divided into the categories of optical effects and mechanical effects. With the emergence of digital filmmaking a distinction between special effects and visual effects has grown, with the latter referring to digital post-production while "special effects" referring to mechanical and optical effects. [custom_adv] Mechanical effects (also called practical or physical effects) are usually accomplished during the live-action shooting. This includes the use of mechanized props, scenery, scale models, animatronics, pyrotechnics and atmospheric effects: creating physical wind, rain, fog, snow, clouds, etc. [custom_adv] Making a car appear to drive by itself and blowing up a building are examples of mechanical effects. Mechanical effects are often incorporated into set design and makeup. [custom_adv] For example, a set may be built with break-away doors or walls to enhance a fight scene, or prosthetic makeup can be used to make an actor look like a non-human creature. [custom_adv] Optical effects (also called photographic effects) are techniques in which images or film frames are created photographically, either "in-camera" using multiple exposure, mattes, or the Schüfftan process, or in post-production using an optical printer. [custom_adv] An optical effect might be used to place actors or sets against a different background.Since the 1990s, computer generated imagery (CGI) has come to the forefront of special effects technologies.
