Computer animation

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Computer animation is the art of creating moving images via the use of computers. It is a subfield of computer graphics and animation. Increasingly it is created by means of 3D computer graphics, though 2D computer graphics are still widely used for low bandwidth and faster real-time rendering needs. Sometimes the target of the animation is the computer itself, but it sometimes the target is another medium, such as film. It is also referred to as CGI (computer generated imagery or computer generated imaging), especially when used in films.

To create the illusion of movement, an image is displayed on the computer screen then quickly replaced by a new image that is similar to the previous image, but shifted slightly. This technique is identical to how the illusion of movement is achieved with television and motion pictures.

Computer animation is essentially a digital successor to the art of stop motion animation of 3D models and frame-by-frame animation of 2D illustrations. For 3D animations, objects (models) are built on the computer monitor (modeled) and 3D figures are rigged with a virtual skeleton. For 2D figure animations, separate objects (illustrations) and separate transparent layers are used, with or without a virtual skeleton. Then the limbs, eyes, mouth, clothes, etc. of the figure are moved by the animator on key frames. The differences in appearance between key frames are automatically calculated by the computer in a process known as tweening or morphing. Finally, the animation is rendered.

For 3D animations, all frames must be rendered after modeling is complete. For 2D vector animations, the rendering process is the key frame illustration process, while tweened frames are rendered as needed. For pre-recorded presentations, the rendered frames are transferred to a different format or medium such as film or digital video. The frames may also be rendered in real time as they are presented to the end-user audience. Low bandwidth animations transmitted via the internet (e.g. 2D Flash, X3D) often use software on the end-users computer to render in real time as an alternative to streaming or pre-loaded high bandwidth animations.

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A simple example

Computer animation exampleThe screen is blanked to a background color, such as black. Then a goat is drawn on the right of the screen. Next the screen is blanked, but the goat is re-drawn or duplicated slightly to the left of its original position. This process is repeated, each time moving the goat a bit to the left. If this process is repeated fast enough the goat will appear to move smoothly to the left. This basic procedure is used for all moving pictures in films and television.

The moving goat is an example of shifting the location of an object. More complex transformations of object properties such as size, shape, lighting effects and color often require calculations and (computer rendering) instead of simple re-drawing or duplication.

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Computer animation development equipment

Computer animation can be created with a computer and animation software. Some examples of animation software are: Amorphium, Art of Illusion, Poser, Ray Dream Studio, Bryce, Maya, Blender, TrueSpace, Lightwave, 3D Studio Max, SoftImage XSI, Alice, and Adobe Flash (2D). There are many more. Prices will vary greatly depending on target market. Some impressive animation can be achieved even with basic programs; however, the rendering can take a lot of time on an ordinary home computer. Because of this, video game animators tend to use low resolution, low polygon count renders, such that the graphics can be rendered in real time on a home computer. Photorealistic animation would be impractical in this context.

Professional animators of movies, television, and video sequences on computer games make photorealistic animation with high detail. This level of quality for movie animation would take tens to hundreds of years to create on a home computer. Many powerful workstation computers are used instead. Graphics workstation computers use two to four processors, and thus are a lot more powerful than a home computer, and are specialized for rendering. A large number of workstations (known as a render farm) are networked together to effectively act as a giant computer. The result is a computer animated movie that can be completed in about one to five years (this process is not comprised solely of rendering, however). A workstation typically costs $2,000 to $16,000, with the more expensive stations being able to render much faster, due to the more technologically advanced hardware that they contain. Pixar's Renderman is rendering software which is widely used as the movie animation industry standard, in competition with Mental Ray. It can be bought at the official Pixar website for about $5,000 to $8,000. It will work on Linux, Mac OS X, and Microsoft Windows based graphics workstations along with an animation program such as Maya and Softimage XSI. Professionals also use digital movie cameras, motion capture or performance capture, bluescreens, film editing software, props, and other tools for movie animation.

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The future

One open challenge in computer animation is a photorealistic animation of humans. Currently, most computer-animated movies show animal characters (Finding Nemo), fantasy characters (Shrek, Monsters Inc.), or cartoon-like humans (The Incredibles). The movie Final Fantasy: The Spirits Within is often cited as the first computer-generated movie to attempt to show realistic-looking humans. However, due to the enormous complexity of the human body, human motion, and human biomechanics, realistic simulation of humans remains largely an open problem. It is one of the "holy grails" of computer animation. Eventually, the goal is to create software where the animator can generate a movie sequence showing a photorealistic human character, undergoing physically-plausible motion, together with clothes, photorealistic hair, a complicated natural background, and possibly interacting with other simulated human characters. This should be done in a way that the viewer is no longer able to tell if a particular movie sequence is computer-generated, or created using real actors in front of movie cameras. Achieving such a goal would mean that conventional flesh-and-bone human actors are no longer necessary for this kind of movie creation, and computer animation would become the standard way of making every kind of a movie, not just animated movies. However, living actors will be needed for voice-over acting and motion capture body movements. Complete human realism is not likely to happen very soon, however such concepts obviously bear certain philosophical implications for the future of the film industry.

For the moment it looks like three dimensional computer animation can be divided into two main directions; photorealistic and non-photorealistic rendering. Photorealistic computer animation can itself be divided into two subcategories; real photorealism (where performance capture is used in the creation of the virtual human characters) and stylized photorealism. Real photorealism is what Final Fantasy tried to achieve and will in the future most likely have the ability to give us live action fantasy features as The Dark Crystal without having to use advanced puppetry and animatronics, while Antz is an example on stylistic photorealism (in the future stylized photorealism will be able to replace traditional stop motion animation as Corpse Bride). None of them are as mentioned perfected yet, but the progress continues. The non-photorealistic/cartoonish direction is more like an extension and improvement of traditional animation, an attempt to make the animation look like a three dimensional version of a cartoon, still using and perfecting the main principles of animation articulated by the Nine Old Men, such as squash and stretch. While a single frame from a photorealistic computer animated feature will look like a photo if done right, a single frame vector from a cartoonish computer animated feature will look like a painting (not to be confused with cel shading, which produces an ever simpler look).

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Movies

CGI short films have been produced as independent animation since the 1970s, though the popularity of computer animation (especially in the field of special effects) skyrocketed during the modern era of U.S. animation. The first completely computer-generated animated movie was Toy Story. See List of computer animated films for more.

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Amateur animation

The popularity of sites such as YouTube, which allows members to upload their own movies for others to view, has created a growing number of what is often considered amateur computer animators. With many free utilities available and programs such as Windows Movie Maker, anyone with the tools can have their animation viewed by thousands.