This capter describes possible applications of systems similar to Ani. A-s a potential maker of interactive animation, some relevant uses of animation are briefly presented. Animation as a communication medium is discussed, especially how its role in communication might expand greatly due to computer technology. The educational applications of Ani are discussed both as a medium for learning about animation and as a producer of instructional films. The potential of knowledge-oriented computer animation for dynamically illustrating programs for docurtientation, instruction, and debugging is presented. The usefulness o, f Ani as a tool of perceptual psychologists is described.
Section A Ani and Animation
One of the most obvious uses of AN is as a producer of animation, While the construction of knowiedge-oriented systems like Ani is difficult, once they are operational tey can produce animation much more easily than by hand or by conventional computer animation systems. The animation can be remade for different audiences or to keep up with changes in the subject matter of the films.
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AnImatioll as Art
We do now hat te cartoon film I's an art as limitless as imagination
itself And within this immense sphere there is surely enough room for a// inds of emotion, for any ventures of man's mind, and not onl for
fun nd entertainment.
Dusan Vukotic a Yugoslavian animator
Ani was dsigned to be an experiment in building a computer system that could mke aniniation as art (as opposed to an ,imation that is primarily entertaining or instructional). If a more sophisticated version of Ani were constructed, perhaps as described in Section A "Making Ani Do More" on page 162, then one might expect it to produce animated films that could serve the same functions as artistic animated film mde by humans currently do. The films produced are likely to seem foreign ince tey were made by a very foreign intelligence, Human animators would not be replaced by systems like Ani, instead the animation domain will be stretched by te production of a "new" kind of film. The films will be different but not different for its own sake. They will differ because of the thinking that created them is different from a human animator. This will be the case for the foreseeable future despite te fact that such a system was designed to make its films in as human a wy as possible. This improved Ani should be able to make films that not
only people enjoy but that also stretches their mnds a little.
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Animation as Entertainment
Animation is most often associated with children's cartoons. Animation is that, but it is often uch more. (See Section G "Animation -- What 'is it?" on page 55 for description Of iLJ$t what animation can be.) Entertaining animation for adults is popular (e.g. "Yellow Submarine", "Fritz the Cat", "Snow White", "Fantasia" and so o n) bU t suffers from the hich production costs. Many are engaged in trying to make computer systems to help alleviate this stuation, as described in Section D
"Relationship to other Computer Graphics Systems it on page 138 and [Kahn I 977d].
These attempts would be more successful f one could communicate with the computer systems at a high level of description. A knowledge-oriented approach is essential in the long run, Of use in the short term Ani is full of low-level animation descriptors that are higher than what is used 'in most computer animation systems, The way in which a character's movements are described 'is the best example.
Objects cn move according to a complex dynamics, have goals that are symbolic (e.g. a good distance from place A and place B), and can interact with others that come in their pths. The way the different activities which the characters are eno',w,'ed in are described and coordinated should also be of value to doing computer graphics researchers interested in making commercial computer animation, Appendix IL The Running of the Cinderella Film" on page 250 describes this aspect of Ani in greater detail.
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Animation as a Language
And therefore the activity of art is an exceedin ly mportant activity,
iu,7t as important as the activity of speech, and just as universal.
---Leo Tolstoy Tolstoy 1898 pge 76
WhY not, indeed, let the basic signs be kinematic? Each "dynamic
/V 0_ 10'-/YP/) FP could then truly "tell a story". A dyn-amic display of dynamic hieroalyphs could represent hundreds or thousands
if7tel'aCtions among tens or hundreds of ideas. To the untrained eye
SLIC17 --7 display would no doubt look like a bucket of worms, but to the trained eye ...
J.C.R. Licklider (Licklider 1976 pg 92
Anim--)tion is a medium of communication and expression that is at least as effective as natur',al language (e.g. English), Natural language is, of course, much easier and cheaper to ue and is terefore much more common. Animation and natural language do not compete t 'pically --- they are each most appropriate in different domains, The significance of tis research- is 'increased by the acceptance of this viewpoint.
No one in the Al community questions the value of research on natural language, so for many of te same reasons they should accept research on the understanding and production of animation.
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A pAcations of A ni A nimation a a Language
Many of he reasons why animation is much ess prevalent than natural langLic)sle concern te difficulties of producing animation, Understanding animation is not considered a serious problem for humans, 'Indeed many consider 'it so easy that it is only appropriate for children. Animation mght become a very prevalent medium of communication and expression if it could be produced with as much ease as, Say, typing a paper. You type to a futuristic Ani what you mean to animate Onstead of typing what you mean to say) and out pops the animation to be seen by yourself or viewers. Licklider [Lickiider 1976] may have been thinking along these line, when he suggested that writing in the future might be like animated Hieroglyphics
Section Ani and Education
The educational uses of an Al-oriented computer animation system were 'Important in te design of an early predecessor of Ani [Kahn I 976a]. The idea was that a properly designed system could be an ideal environment for a student to learn about both Al and animation. Thi's design criterion was dropped for practical reasons in the making of Ani, Nonetheless, Ani could be viewed as a paradigm of how a skill could be taught to humans by conveying how that skill could be embedded in a machine. Since Ani is a manipulable glass box, a student of animation COUld -learn much by observing the effects of aering Ani's knowledge and rules.
Ani's knowledge is in an explicit form that can be studied in ways that the
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knowl edge of a uan animator cannot, A student could also replace Ani's knowled-,e base with is or er own knowledge and see how a very crude simulation of temselves as animators performs.
Ani is dessigned to produce entertain' sthetic films but another system could be bi I t Uon similar principles whose purpose is to produce nstructional films or dyncariiic diagrams, Such a system would know enough about pedagogy that it
Could produce- its films with relatively little interaction with humans. In the not-so-distant future, one might expect an educational version of Ani to produce films on the fly to help intelligent tutoring systems such as those described 'in [Goldstein 1 9771. If a picture 'is worth a thousand words, what i's a short animated film consisting of thousands of pictures worth?
Section Illustrating Programs
Anin7atiOn, MUSic, and programming can be thought of as different se-ns.ory views of dynamic processes.
--Alan Kay [Kay 19771 p, k 5
One exciting possible application of this research is the construction of a system
that Cld animate programs. One could see a visual trace of a program in operation for debugging, or an animated metaphor of an algorithm in operation for
teaching people what it does and how. One could interactively "fly" through the database of a complex program, diving" into what is of nterest, sailing quickly over
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other prts. The animation can be tailored to a simple model of the viewer. A progrc-inin-ier cran change a program and a new film of 'Its operation can be automatically generated
It has long been known that visual presentation is a great aid to learning about, understanding, and thinking about complex processes. An animated dynami .c presentation is of even more value. An example 'is the work of Baecker and his colleagues at the University of Toronto [Baecker 1978]. They have produced two different types of animated films of programs. The first were programs in execution where one visually sees stacks pushed and popped, variables bound, functions called (even recursively) and so on. These films were generated from the programs themselves and terse illustration specifications. Their effectiveness was limited, however, because of their eavy use of textual information and their extreme graphic simplicity, The other films made at Toronto were much more effective and Visually interesting. Nine different sorting algorithms were visualized as factory machinery with the data being moved along on conveyor belts frequently being operated upon by machines as they passed by. Unfortunately these films were hand-crafted in the sense that each film had to be explicitly programmed at a relatively low-level. Clearly what would be desirable would be a system that could produce films with the ease of the Logo program vsualizer and of the quality and effectiveness of the sorting and hashing films.
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iflustrating Programs AppliUltiotis of Ani What is needed to make such a program visualizer? For one, the kinds of knowled,-e -Find expertise that is in a system like Ani. The system will need to make man choices ram-fing from wat visual metaphor to use, to how to graphically
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represent the objects and processes of the program, to where to place a particular component nd how big it sould be. In order to animate a program one needs to understand it. It is nILIch too ambitious a project for the visualizer to automatically 1CICCOmplk-,h this, o te system would need to be provided an annotated description of the prop-ram and its organization. This is analogous to the situation where- Ani applies aencral animation knowledge to a user-provided film description to make films, The program visualizer would apply its knowledge of animation and programming to a user-provided program description.
The actor philosophy of computation can play a significant role in program
i I I UStration. it provides a good bottom level dynamic graphic representation of computation as actors sending and receiving messages. The actor event diagrams developed by Hewitt is a good start. A ma'or difficulty with them is that they are trying to represent concurrent dynamic processes wth static drawings. Real-time interiactive animation would alleviate many of the problems 'Involved in showing how a omplex program, especially a parallel one, works.1
I A pro need 110t be I&Jittell ill 'll aCtOl' 1,111gWige for this graphic representation to be of vlue.
Many 5V'Str-111 pro"".1-anis ntwork programs. oi- ost programs with a high dgree of odularity call be
prof Itably "'Iewed as Consisting of separate etities that pass messages between hemselves.
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A pplIC(A t 011S of A ni A ni as a Tool of a Percelxual Psychologist
Section D Ani as a Tool of a Perceptual Psychologist
AN cc-in be viewed as a producer of material for perceptual psychology. The perception of dynamic qualities of a scene such as causality, emotions, inter-personal interactions, and activities is an important ability of humans that warrants tudy.' Ani is an ideal source of stimuli for such experiments. Ani can generate episodes which are presented to sub'ects to fnd out what are the critical parameters in a motion to produce a particular characterization, mood, or 'Interaction.
One bility of AN is to produce minor variants of the same film. A study based pon these variations would be prohibitively expensive by almost any other means. A system like Ani enables one to control not only low level details such as the exact size of a particular character but also high level parameters such as the kind of rhythrn or the relationship between two characters. A symbiosis is possible where Ani's knowledge gets refined by psychological experimentation and the psychological experimentation is aided by an excellent source of stimuli. For example, a psychologist might be interested 'in what dynamics evoke the idea that an object is aft-aid. Subjects could view films of characters acting afraid made by AN and the findings can be used to refine Ani's methods and suggestions. New (and
1. Nichotte 9501, Michotte 190). Weir 1975). nd (Heider 1944) are the oly ntances of sch ,Studies that I ani aware of.
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presumably ore effective) films can then be made and the process repeated.
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'"' lirr A i's Suggrstiolis Come From