Computer-generated imagery
From Wikipedia, the free encyclopedia
Computer-generated imagery[1] (also known as CGI) is the application of the field of computer graphics or, more specifically, 3D computer graphics to special effects in films, television programs, commercials, simulators and simulation generally, and printed media. Video games usually use real-time computer graphics (rarely referred to as CGI)[citation needed], but may also include pre-rendered "cut scenes" and intro movies that would be typical CGI applications. These are sometimes referred to as FMV (Full motion video).
CGI is used for visual effects because computer generated effects are more controllable than other more physically based processes, such as constructing miniatures for effects shots or hiring extras for crowd scenes, and because it allows the creation of images that would not be feasible using any other technology. It can also allow a single graphic artist to produce such content without the use of actors, expensive set pieces, or props.
3D computer graphics software is used to make computer-generated imagery for movies, etc. Recent availability of CGI software and increased computer speeds have allowed individual artists and small companies to produce professional grade films, games, and fine art from their home computers. This has brought about an Internet subculture with its own set of global celebrities, clichés, and technical vocabulary.
Simulators, particularly flight simulators, and simulation generally, make extensive use of CGI techniques for representing the outside world.[2]
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[edit] History
CGI was first used in movies in 1973's Westworld, though the first use of 3D Wireframe imagery was in its sequel, Futureworld (1976), which featured a computer-generated hand and face created by then University of Utah graduate students Edwin Catmull and Fred Parke. The third movie to use this technology was Star Wars (1977) for the scenes with the wireframe Death Star plans and the targeting computers in the X-wings and the Millennium Falcon. In 1978, graduate students at the New York Institute of Technology Computer Graphics Lab began work on what would have been the first full-length CGI film, The Works, and a trailer for it was shown at SIGGRAPH 1982, but the film was never completed. Star Trek II: The Wrath of Khan premiered a short CGI sequence called The Genesis Wave in June 1982. The first two films to make heavy investments in Solid 3D CGI, Tron (1982) and The Last Starfighter (1984), were commercial failures, causing most directors to relegate CGI to images that were supposed to look like they were created by a computer.
It was the 1993 film Jurassic Park, however, in which dinosaurs created with CGI were seamlessly integrated into live action scenes, that revolutionized the movie industry. It marked Hollywood’s transition from stop-motion animation and conventional optical effects to digital techniques. The following year, CGI was used to create the special effects for Forrest Gump. The most noteworthy effects shots were those that featured the digital removal of actor Gary Sinise's legs. Other effects included a napalm strike, the fast-moving Ping-Pong balls, and the digital insertion of Tom Hanks into several scenes of historical footage.
2D CGI increasingly appeared in traditionally animated films, where it supplemented the use of hand-illustrated cels. Its uses ranged from digital tweening motion between frames, to eye-catching quasi-3D effects, such as the ballroom scene in Beauty and the Beast.
In 1993, Babylon 5 became the first television series to use CGI as the primary method for its visual effects (rather than using hand-built models). It also marked the first TV use of virtual sets. That same year, Insektors became the first full-length completely computer animated TV series[3]. Soon after, in 1994, the hit Canadian CGI show ReBoot aired.
In 1995, the first fully computer-generated feature film, Disney-Pixar's Toy Story, was a resounding commercial success. Additional digital animation studios such as Blue Sky Studios (20th Century Fox), DNA Productions (Paramount Pictures and Warner Bros.), Omation Studios (Paramount Pictures), Sony Pictures Animation (Columbia Pictures), Vanguard Animation (Walt Disney Pictures, Lions Gate Entertainment and 20th Century Fox), Big Idea Productions (Universal Pictures and FHE Pictures), Animal Logic (Warner Bros.) and Pacific Data Images (Dreamworks SKG) went into production, and existing animation companies, such as The Walt Disney Company, began to make a transition from traditional animation to CGI.
Between 1995 and 2005 the average effects budget for a wide-release feature film skyrocketed from $5 million to $40 million. According to one studio executive, as of 2005[update], more than half of feature films have significant effects. However, CGI has made up for the expenditures by grossing over 20% more than their real-life counterparts.[4]
In the early 2000s, computer-generated imagery became the dominant form of special effects. The technology progressed to the point that it became possible to include virtual stunt doubles. Camera tracking software was refined to allow increasingly complex visual effects developments that were previously impossible. Computer-generated extras also became used extensively in crowd scenes with advanced flocking and crowd simulation software. The timeline of CGI in film and television shows a detailed list of pioneering uses of computer-generated imagery in film and television.
CGI for films is usually rendered at about 1.4–6 megapixels.[citation needed] Toy Story, for example, was rendered at 1536 × 922 (1.42MP). The time to render one frame is typically around 2–3 hours, with ten times that for the most complex scenes. This time hasn't changed much in the last decade, as image quality has progressed at the same rate as improvements in hardware, since with faster machines, more and more complexity becomes feasible. Exponential increases in GPUs processing power, as well as massive increases in parallel CPU power, storage and memory speed and size have greatly increased CGI's potential.
In 2001, Square Pictures created the CGI film Final Fantasy: The Spirits Within, which made headlines for attempting to create photo-realistic human actors. The film was not a box-office success. Some commentators have suggested this may be partly because the lead CGI characters had facial features which fell into the uncanny valley. Square Pictures produced only two more films using a similar visual style Final Flight of the Osiris, a short film which served as a prologue to The Matrix Reloaded and Final Fantasy VII: Advent Children, based on their extremely popular video game series.
Developments in CGI technologies are reported each year at SIGGRAPH, an annual conference on computer graphics and interactive techniques, attended each year by tens of thousands of computer professionals.
Developers of computer games and 3D video cards strive to achieve the same visual quality on personal computers in real-time as is possible for CGI films and animation. With the rapid advancement of real-time rendering quality, artists began to use game engines to render non-interactive movies. This art form is called machinima.
[edit] Creating characters and objects on a computer
3D computer animation combines 3D models of objects and programmed movement. Models are constructed out of geometrical vertices, faces, and edges in a 3D coordinate system. Objects are sculpted much like real clay or plaster, working from general forms to specific details with various sculpting tools. A bone/joint system is set up to deform the 3D mesh (e.g., to make a humanoid model walk). In a process called rigging, the virtual marionette is given various controllers and handles for controlling movement. Animation data can be created using motion capture, or keyframing by a human animator, or a combination of the two.
3D models rigged for animation may contain hundreds of control points - for example, the character "Woody" in Pixar's movie Toy Story, uses 700 specialized animation controllers. Rhythm and Hues Studios labored for two years to create Aslan in the movie The Chronicles of Narnia: The Lion, the Witch and the Wardrobe which had about 1851 controllers, 742 in just the face alone. In the 2004 film The Day After Tomorrow, designers had to design forces of extreme weather with the help of video references and accurate meteorological facts.
For the 2005 remake of King Kong, actor Andy Serkis was used to help designers pinpoint the gorilla's prime location in the shots and used his expressions to model "human" characteristics onto the creature. Serkis had earlier provided the voice and performance for Gollum in Peter Jackson's The Lord of the Rings trilogy.
[edit] Communities
There are a multitude of websites designed to help promote and support CGI artists. Some are managed by software developers and content providers, but there are standalone sites as well, including one of the largest communities on the web, Renderosity. These communities allow for members to seek advice, post tutorials, provide product reviews or post examples of their own work.
[edit] CGI film studios
- Blue Sky Studios
- DreamWorks Animation
- Pacific Data Images
- Pixar
- Walt Disney Animation Studios
- Sony Pictures Imageworks
