Inbetweening, also commonly known as tweening, is a key process in all animation - including computer animation - where immediate frames, called inbetweens, between two key frames are generated to give the appearance that the first image evolves and moves smoothly into the second image to create the illusion of movement.
Traditional animation
Traditional inbetweening involves the use of light tables to draw a set of pencil-on-paper pictures.[1]
The process of inbetweening with traditional animation starts with the senior or key artist drawing the key frames which define movement. After testing, and approval of the rough animation, the scene would be passed down to their assistant who moves on to clean-up and add the necessary inbetweens, or in large studios only the breakdowns, which define the movement in more detail. Following this, the scene is then handed down to the assistant of the keyframe assistant, the inbetweener which completes the animation. Dick Huemer created this system due to it's efficient nature, it has been used since the 1920s.[2] If the animation team is small, animators will often do the inbetweening process and complete the animation amongst themselves.
Frame frequency
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Typically, an animator does not draw inbetweens for all 24 frames required for one second of film. Only very fast movements require animation "on ones", as it is called. Most movements can be done with 12 drawings per second, which is called animating "on twos". When the number of inbetweens is too few, such as 4 frames per second, it will begin to lose the illusion of movement altogether. Computer generated animation is usually animated on ones. The decision about the number of inbetweens is also an artistic one, as certain styles of animation require a not-so-smooth fashion of movement. Animation "on twos" dates to the dawn of animation – Fantasmagorie (1908), widely considered the first fully animated movie, was animated on twos.
Modern animation will use various techniques to adapt the framerate to the current shot. Slow movements may be animated on threes or fours. Different components of a shot might be animated at different framerates – for example, a character in a panning shot might be animated on twos, while everything in the shot is shifted every frame to accomplish the pan. Optical effects such as motion blur may be used to simulate the appearance of a higher framerate.
Digital animation
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When animating in a digital context, the shortened term tweening is commonly used, and the resulting sequence of frames is called a tween. Sophisticated animation software enables the animator to specify objects in an image and define how they should move and change during the tweening process. Software may be used to manually render or adjust transitional frames by hand, or may be used to automatically render transitional frames using interpolation of graphic parameters.
Some of the earliest software that utilises automatic interpolation in the realm of digital animation include Macromedia Flash[3] and Animo[4] (developed by Cambridge Animation Systems) in the late 90s, and Tweenmaker,[5] released around 2006.[6][7] The free software program Synfig specializes in automated tweening.
"Ease-in" and "ease-out" in digital animation typically refer to a mechanism for defining the physics of the transition between two animation states, i.e., the linearity of a tween.[8]
The use of computers for inbetweening was enhanced by Nestor Burtnyk and Marceli Wein at the National Research Council of Canada. They received a Technical Achievement Academy Award in 1997, for "pioneering work in the development of software techniques for computer assisted key framing for character animation".[9]
See also
- Anime Studio
- Flicker fusion threshold
- Morphing
- Onion skinning
- Motion blur
- Synfig a Free and Open Source Software (FOSS) tweener
References
- ^ InBetweening - How to do proper in betweening, retrieved 2020-01-17
- ^ Williams, Richard (2002). The Animator's Survival Kit. Faber & Faber; 2nd edition. p. 48. ISBN 978-0571202287.
- ^ Calop, Guillaume (1997). Animation World Magazine - March 1997 (PDF). Animation World Network. p. 55.
- ^ Animo Vectors, retrieved 2020-01-17
- ^ TweenMaker, retrieved 2020-01-17
- ^ "TweenMaker | Home". www.elecorn.com. Retrieved 2020-01-17.
- ^ "TweenMaker". Download.com. Retrieved 2020-01-17.
- ^ "Tweener Documentation and Language Reference". hosted.zeh.com.br.
- ^ "Nestor Burtnyk, Ken Pulfer, and Marceli Wein • Graphics Interface". Graphics Interface. Retrieved 2020-01-17.