Computer animation
Computer animation is the process used for digitally generating moving images. The more general term computer-generated imagery encompasses both still images and moving images, while computer animation refers to moving images. Modern computer animation usually uses 3D computer graphics.
Computer animation is a digital successor to stop motion and traditional animation. Instead of a physical model or illustration, a digital equivalent is manipulated frame-by-frame. Also, computer-generated animations allow a single graphic artist to produce such content without using actors, expensive set pieces, or props. To create the illusion of movement, an image is displayed on the computer monitor and repeatedly replaced by a new similar image but advanced slightly in time. This technique is identical to how the illusion of movement is achieved with television and motion pictures.
To trick the visual system into seeing a smoothly moving object, the pictures should be drawn at around 12 frames per second or faster. At rates below 12 frames per second, most people can detect jerkiness associated with the drawing of new images that detracts from the illusion of realistic movement. Conventional hand-drawn cartoon animation often uses 15 frames per second in order to save on the number of drawings needed, but this is usually accepted because of the stylized nature of cartoons. To produce more realistic imagery, computer animation demands higher frame rates.
Films seen in theaters in the United States run at 24 frames per second, which is sufficient to create the appearance of continuous movement.
Computer-generated animation
Computer-generated animation is an umbrella term for three-dimensional animation, and 2D computer animation. These also include subcategories like asset driven, hybrid, and digital drawn animation. Creators animate using code or software instead of pencil-to-paper drawings. There are many techniques and disciplines in computer generated animation, some of which are digital representations of traditional animation - such as key frame animation - and some of which are only possible with a computer - such fluid simulation.'CG' Animators can break physical laws by using mathematical algorithms to cheat mass, force and gravity, and more. Computer-generated animation is a powerful tool which can improve the quality of animation by using the power of computing to unleash the animator's imagination. This is because computer-generated animation allows for things like onion skinning which allows 2D animators to see the flow of their work all at once, and interpolation which allows 3D animators to automate the process of inbetweening.
| Movie | Type of Computer Generated Animation | Impact |
| Toy Story 2 | Stylized 3D computer animation | Pixar developed cutting-edge technology for fully 3D animation. 'Toy Story' is considered a turning point for 3D animation in general. |
| Godzilla Minus One | Digital VFX, photorealistic | Toho studios won an Oscar for its ground breaking VFX on a small budget relative to most box-office movies. |
| The Breadwinner | 2D computer animation | Was praised for its 2D animated style, showing the possibilities of what the format could portray. |
| Interstellar | Photorealistic CGI following scientific principles | The VFX artists working on Interstellar published a paper about the science and mathematics that were used to create the famous 'Gargantua' black hole. |
| Klaus | Hybrid 3D and 2D computer animation | The use of 3D lighting for 2D animation in this movie opened up a door to many new animation styles for 2D animators. |
3D computer animation
Overview
For 3D computer animations, objects are built on the computer monitor and 3D figures are rigged with a virtual skeleton. Then the limbs, eyes, mouth, clothes, etc. of the figure are moved by the animator on key frames. Normally, the differences between key frames are drawn in a process known as tweening. However, in 3D computer animation, this is done automatically, and is called interpolation. Finally, the animation is rendered and composited.Before becoming a final product, 3D computer animations only exist as a series of moving shapes and systems within 3d software, and must be rendered. This can happen as a separate process for animations developed for movies and short films, or it can be done in real-time when animated for videogames. After an animation is rendered, it can be composited into a final product.
Animation attributes
For 3D models, attributes can describe any characteristic of the object that can be animated. This includes transformation, scaling, rotation, and more complex attributes like blend shape progression. Each attribute gets a channel on which keyframes can be set. These keyframes can be used in more complex ways such as animating in layers, or keying control objects to deform or control other objects. For instance, a character's arms can have a skeleton applied, and the joints can have transformation and rotation keyframes set. The movement of the arm joints will then cause the arm shape to deform.Interpolation
3D animation software interpolates between keyframes by generating a spline between keys plotted on a graph which represents the animation. Additionally, these splines can follow Bézier curves to control how the spline curves relative to the keyframes. Using interpolation allows 3D animators to dynamically change animations without having to redo all the in-between animation. This also allows the creation of complex movements such as ellipses with only a few keyframes. Lastly, interpolation allows the animator to change the framerate, timing, and even scale of the movements at any point in the animation process.Procedural and node-based animation
Another way to automate 3D animation is to use procedural tools such as 4D noise. Noise is any algorithm that plots pseudo-random values within a dimensional space. 4D noise can be used to do things like move a swarm of bees around; the first three dimensions correspond to the position of the bees in space, and the fourth is used to change the bee's position over time. Noise can also be used as a cheap replacement for simulation. For example, smoke and clouds can be animated using noise.Node-based animation is useful for animating organic and chaotic shapes. By using nodes, an animator can build up a complex set of animation rules that can be applied either to many objects at once, or one very complex object. A good example of this would be setting the movement of particles to match the beat of a song.
Disciplines of 3D animation
There are many different disciplines of 3D animation, some of which include entirely separate artforms. For example, hair simulation for computer animated characters in and of itself is a career path which involves separate workflows, and different software and tools. The combination of all or some 3D computer animation disciplines is commonly referred to within the animation industry as the 3D animation pipeline.| Discipline | Explanation | Tools | Examples |
| Face Rigging | A facial rig is a rig that includes muscles, deformation, mesh displacement, and other techniques to enable the animation of facial expressions, and phonemes for lip syncing. | Autodesk Maya, Blender | In 'Avatar, Way of Water', WETA workshops meticulously designed the digital muscles in the faces of their characters so that their emotional range could be comparable to that of a human. |
| Facial Animation | This is the process of animating facial animations, lip-syncing, and animating phoneme blend-shapes | Autodesk Maya, Blender, Autodesk 3DS Max | In Pixar's 'Turning Red', animators took influence from anime style facial expressions to inform their animation. |
| Character Animation | Specifically the animation of characters. 3D character animation is its own specialty due to the complexity required to animated dancing, running, fighting, or high fidelity motion such as playing basketball. | Autodesk Maya, Blender | Pixar's 'Incredibles' won the 2004 Visual Effects Society Award for Outstanding Animated Character in an Animated Feature |
| Cloth Simulation | Cloth simulation is a subset of simulation but specifically for things like clothes. In modern 3D computer animation, cloth simulation is becoming more and more advanced and widely used. | Houdini, Blender | Pixar's 'Coco' advanced the use of high fidelity clothes by designing new tools to combine cloth simulation with character animation. |
2D computer animation
are still used for stylistic, low bandwidth, and faster real-time renderings.Computer animation is essentially a digital successor to stop motion techniques, but using 3D models, and traditional animation techniques using frame-by-frame animation of 2D illustrations.
For 2D figure animations, separate objects and separate transparent layers are used with or without that virtual skeleton.
2D sprites and pseudocode
In 2D computer animation, moving objects are often referred to as "sprites." A sprite is an image that has a location associated with it. The location of the sprite is changed slightly, between each displayed frame, to make the sprite appear to move. The following pseudocode makes a sprite move from left to right:var int x := 0, y := screenHeight / 2;
while x < screenWidth
drawBackground
drawSpriteAtXY // draw on top of the background
x := x + 5 ''// move to the right''
Computer-assisted animation
Computer-assisted animation is usually classed as two-dimensional animation and is also known as digital ink and paint. Drawings are either hand drawn or interactively drawn using different assisting appliances and are positioned into specific software packages. Within the software package, the creator places drawings into different key frames which fundamentally create an outline of the most important movements. The computer then fills in the "in-between frames", a process commonly known as Tweening. Computer-assisted animation employs new technologies to produce content faster than is possible with traditional animation, while still retaining the stylistic elements of traditionally drawn characters or objects.Examples of films produced using computer-assisted animation are the rainbow sequence at the end of The Little Mermaid, The Rescuers Down Under, Beauty and the Beast, Aladdin, The Lion King, Pocahontas, The Hunchback of Notre Dame, Hercules, Mulan, Tarzan, We're Back! A Dinosaur's Story, Balto, Anastasia, Titan A.E., The Prince of Egypt, The Road to El Dorado, Spirit: Stallion of the Cimarron and Sinbad: Legend of the Seven Seas.