Computer Animation - An Exciting New Tool for Educators

Donald D Weiner

Syracuse University

November 1971

IEEE Transactions on Education, November 1971

Abstract

A tutorial paper on computer animation is presented that answers the following questions:

1. What is computer animation and how did it begin?
2. Who is active in the area?
3. What is the present state of the art?
4. How is computer animation accomplished in a batch-processing environment?
5. What is the role of interactive graphics?
6. What are some of the special techniques that are being developed?
7. How does one get started?

In addition, extensive bibliographies on computer animation publications and flms are included.

INTRODUCTION

COMPUTER animation is an automated procedure in which a computer is used to compute the frame-by-frame positions of animated objects and characters. This newly emerging technique offers the individual educator a potentially effective tool for creating movies to better illustrate subject matter difficult for students to visualize and understand.

Educational films, for the most part, have previously utilized the inverse funnel approach [121]. With this approach a few well-known scientists, teachers, and filmmakers join forces to produce a highly professional film that is often very expensive. As Zajac points out, one can envision the filmmakers at the neck of a funnel with their efforts expanding outward to a mass audience. The high cost, typically greater than $30,000 for a 15-min flm, restricts the number of ideas that can be tried. In addition, films circulated for wide distribution are frequently considered to be ineffective. For the instructor who wishes to present his material in a particular way, the films produced by the funnel approach may emphasize certain unwanted features, may not use the desired approach to the topic, or may employ undesirable terminology and/or notation.

Accordingly, it is important that teachers be able to produce their own films. In this manner, they are able to display the critical parts of their lessons in ways that complement other aspects of their teaching. Computer animation provides a means for achieving the above objective.

EARLY SUCCESSES

The use of computers in the production of motion pictures is relatively new. Some of the earliest work occurred at the Bell Telephone Laboratories where a computer-generated movie was produced by Ed Zajac in 1963 [40]. By illustrating a tumbling communications satellite orbiting the earth, Zajac was able to study and explain the effect of gyros used to orient and stabilize the satellite so as to keep its antennas pointed earthward. Another early film from Bell Labs., Force, Mass, and Motion, by Frank Sinden [15], demonstrated the motion of two heavenly bodies under the force of gravity. In addition to considering the usual inverse square law of nature, Sinden examined motions resulting from other hypothetical gravitational forces such as those that vary with distance as r^-3, r^-1, and r². To many educators this 10-min film proved beyond doubt that computer animation can be used as an effective educational tool.

Whereas Zajac and Sinden used standard Fortran to produce movies consisting of simple animated line drawings, Ken Knowlton [28] of Bell Labs. developed in 1964 a special programming language, called Beflix (Bell Flicks), to facilitate the production of motion pictures comprised of dynamic shaded-area drawings. The addition of shading was not Knowlton's primary objective. Rather, he attempted to make easier the specification of images to the computer. Beflix uses such instructions as PAINT (paint a specified area a given shade of gray), ZOOM (zoom in on the picture), ROTATE (rotate a rectangular array a specified amount), DISOLV (dissolve one rectangular area into another area of similar size and shape), etc. In this way, the computer program consists of a description of the movie that uses, to a large extent, the language of the filmmaker.

Other pioneering work in computer-generated films was done at the Boeing Company [7], the Los Alamos Scientific Laboratory [124], and the Lawrence Radiation Laboratory [3]. The Boeing work, concerned largely with aircraft design and cockpit visibility, resulted in the first films simulating aircraft carrier landings. At Los Alamos, where computer animation was originally used in the study of fluid dynamics, early films gave beautiful and impressive displays of breaking water waves and water flowing beneath a sluice gate. Lawrence Radiation Laboratory produced the first color computer-generated movies treating such scientific subjects as the propagation of shock waves in solids and the earth's weather as predicted by a mathematical meteorological model.

For the most part, the early attempts at computer animation were carried out in a batch-processing environment. In this mode of operation the motion picture script, detailing the sequences to be animated, is first translated into a computer program. The program is then submitted to the computer, usually in the form of a deck of punched cards. The computer processes the program and generates a magnetic tape that contains all the information needed to produce the movie frame by frame. The magnetic tape is fed to a microfilm recorder, a device that contains a cathode ray tube (CRT) and a stop-action animation camera focused at the face of the CRT. In response to the instructions on the magnetic tape, the camera shutter is opened and the beam of the CRT traces out the lines that comprise the first frame. On completion of the frame, the shutter is closed and the film is advanced. This process is repeated for each subsequent frame until the entire movie has been recorded on film.

MOVIE LANGUAGES FOR THE BATCH-PROCESSING ENVIRONMENT

Where movies are concerned, thousands of frames of film are usually required. A 5-min movie running at 24 frames per second consists of 7200 frames. In the batch-processing mode of operation the animator is handicapped by the fact that graphical information must be imparted to the computer in a nongraphical manner, e.g., a deck of punched cards. To ease the communications problem, several computer-animation movie languages have emerged that enable basic figures and motions to be drawn by means of a small number of instructions. For example, a single instruction may cause a circle or transistor to be drawn at a particular position on the screen or may cause an object to be translated from one side of the screen to the other in a specified number of frames. Typically, a program containing 100 instructions will generate several hundred frames of film. In addition, the names of the commands and their associated parameters are usually derived from common English words descriptive of the actual graphical procedures involved. In this way, the unfriendly batch-processing environment is made more palatable to the animator.

The movie languages incorporate, in general, many identical features. In terms of a single frame, capability is usually provided for plotting points, drawing lines and basic geometrical figures, and lettering in one or more fonts. With regard to motion from frame to frame, provision is usually made for the scaling, translation, and rotation of objects. Special effects such as zooms, dissolves, erasures, masking, and windowing are often included. Commands are also available for controlling the camera to allow for multiple exposures and advance of the film.

Beflix [28], [29], chronologically the first movie language, is one of the most elaborate. Instead of using the microfilm recorder in the vectoring mode where straight lines are drawn from one point to another, Knowlton utilized the typewriter mode where characters of fixed size are typed on the face of the CRT. Frames produced in this manner are comprised of thousands of tiny characters resulting in a mosaic effect. To turn the finely structured characters into contiguous blobs of gray, the camera is slightly defocused.

Although the microfilm recorder is capable of resolving approximately 1,000,000 different points on a 1024-by-1024 grid, Beflix divides each frame into 46,384 square areas, 252 squares wide and 184 squares high, in order to reduce the required computation. Each square is assigned one of eight possible gray levels by automatically positioning various characters at different locations within the square. Because of the considerable computation needed to produce a single frame, the computer generates only one picture for each sequence of identical frames in the final movie. The additional frames are produced by standard duplication procedures at an optical house. By way of example, A Computer Technique for the Production of Animated Movies is a 17-min silent film produced by Ken Knowlton using Beflix. It contains approximately 25,000 frames. Since many frames are identical, so as to allow the viewer time to read the titles, only 3000 unique pictures were generated by the computer. These 3000 pictures required approximately 2000 instructions of Beflix programming. Knowlton estimates the cost of this movie, in which every area of the screen is painted some shade of gray, at about $600 per minute of projected film.

A second movie language, referred to as Pmacro [22], [27], was developed in 1965 by Bill Huggins of Johns Hopkins University while on leave of absence at Bell Labs. This language, consisting of a set of macros written in Befap, was designed to simplify the generation of animated movies using line drawings of rotating phasors to illustrate sinusoidal signals, sidebands, and modulation phenomena. Under the sponsorship of the National Committee on Electrical Engineering Films (NCEEF), Pmacro was used to produce two early computer-animated movies entitled, Harmonic Phasors and Response of a Resonant System to a Frequency Step. These educational films, produced as computer pantomimes [105], experiment with the technique of conveying abstract ideas without the use of traditional words and mathematical symbols. They suggest that computer animation opens new possibilities for using dynamic symbols to clarify and demonstrate abstract relationships and concepts. Pmacro was also used in the generation of the computer-animated sequences appearing in a pair of films [112] entitled, Complex Waves I: Propagation, Evanescence, and Instability and Complex Waves II: Instability, Convection, and Amplification. This animation work was quite novel in that the mathematical aspects of dynamical waves were illustrated simultaneously on the screen along with the actual physical phenomena. The movies illustrate how computer animation can be used to create animated sequences that are precisely synchronized to the live experiment photographed in the studio.

Additional movie languages are: 1) Polygraphics [31], [24], [61], [64] (Polytechnic Institute of Brooklyn); 2) Camp/Camper [32], [23], [33] (Syracuse University) ; 3) Solids [25] (Ling-Temco-Vought Aerospace Corp.); and 4) Groats [26] (Atlas Computer Laboratory, England). Each of these packages has in common the objective of providing people without computer programming experience a means for using computer animation. Although they differ somewhat in concept, they do provide similar capabilities in terms of animating simple line drawings. It is noteworthy that the programming of the Polygraphics and Camp/Camper software was accomplished by students at their respective schools. Costs for movies produced by these languages appear to average around $100 per minute of projected film. The Polygraphics and Camp/Camper packages are written in Fortran for ease of implementation on different machines and are available upon request at no cost.

Computer installations not having microfilm recorders are faced with the problem of debugging their movie programs. At Syracuse University the magnetic tapes generated by the computer are mailed for processing to the nearest microfilm recorder, located at the Polytechnic Institute of Brooklyn, approximately 300 miles away. In order to eliminate long delays during the debugging and experimental phase of the movie, selected frames are plotted on the university's relatively slow Cal-Comp plotter. At Johns Hopkins University, use is made of the line printer to help with the debugging. To further alleviate the situation, long movies are usually programmed in 2-min segments. While waiting for one 2-min segment to be processed, programming proceeds on the next. This, combined with the fact that careful design of the movie script is more time consuming and difficult than the straightforward task of writing and processing the computer program [106], tends to minimize the inconvenience of not having the microfilm recorder readily available.

SPECIAL TECHNIQUES

A recent listing of people active in computer animation included 151 individuals employed by 19 universities, 30 industrial firms, and 16 governmental or not-for-profit agencies [[18]. With the increasing interest in, and enthusiasm for, computer animation, considerable effort has been devoted to such special effects as perspective drawings, hidden-line removal, gray-scale animation, and color. Each of these techniques is briefly discussed below.

Perspective Drawings

A three-dimensional object is drawn onto a two-dimensional screen by projecting its vertices onto a picture plane as seen from a specified viewing point. The basic transformation needed for the projection is mathematically straightforward. Thus, it is easy for the computer to draw three-dimensional objects in true perspective [[40]. This capability is included in the Polygraphics, Camp/Camper, and Solids animation languages mentioned previously.

In applications where portions of complicated three-dimensional objects that should be hidden are not removed, a single perspective drawing may be difficult to interpret. To overcome this difficulty, Mike Noll suggested a technique that results in a realistic three-dimensional picture [36], [37], [126]. with this technique, perspective drawings, as seen by the left and right eyes, are viewed stereoptically to fuse the two perspective images into a single view having a true three-dimensional effect.

Hidden-Line Removal

The problem of determining those portions of a solid object that are obscured from view is by no means trivial. Algorithms to solve the hidden-line problem have been in existence for several years [53], [48], [41], [47]. The difficulty is that the computation time required for a single view of an object may vary from several seconds to several minutes, depending upon the complexity of the object. If only a small number of drawings are of interest, this is of little concern. However, where movies are apt to involve several thousand frames of film, the expense incurred is too prohibitive.

Instead of searching out all surfaces hidden from view, one can use an alternate approach in which only the visible portion of surfaces is drawn. Using this approach, Magi developed a ray-tracing technique that eliminates the hidden-line problem by terminating rays incident on an opaque surface [44]. The alternate approach has also been followed at the University of Utah where a series of algorithms for displaying only the visible portions of surfaces has evolved [54], [40], [51], [52]. The work by Gary Watkins is of particular significance since it is anticipated that his algorithm can be implemented by special-purpose hardware that will enable shaded pictures of solids to be generated and displayed in real time at speeds up to 30 frames per second.

Gray-Scale Animation

Gray scale animation is another special effect being studied. As discussed earlier, Beflix [28] divides the screen into a large number of square areas of fixed size. The shaded picture is synthesized by assigning various levels of gray to each of the small areas. A similar approach is taken in the Acians system developed at IBM [81]. Black and white pictures are stored digitally as a matrix of zeros and ones. This representation allows all points of the frame to be displayed. The picture is created dynamically by horizontally scanning the binary matrix. Horizontal lines of fixed size are drawn only when ones are encountered in the matrix. In another approach, shading is accomplished by automatically filling in a given area with a family of equally spaced parallel lines [45].

Raster displays, in which the beam of the tube moves in a fixed sequence from left to right and from top to bottom, are best suited for the production of shaded pictures. The added complication is that information for a raster display must first be sorted so that it can be displayed on the screen in the correct sequence as the raster is scanned. By simulating a raster display, researchers at the University of Utah have generated impressive pictures of solids shaded with varying highlights [54]. [62], [94].

Color

Because the resolution of color TV tubes is less than that required in motion picture work, they have not normally been used in the generation of color images. Color has been accomplished by means of two different techniques [5]. In the first technique, clear, red, green, and blue filters are mounted on a color wheel placed between the CRT and the camera. The camera is loaded with color film and the appropriate filter is selected by using a stepping motor operated under program control. Full color capability is achieved by generating three separate pictures sequentially on the CRT and photographing each picture on the same film frame through the correct color filter. This technique has been pioneered both at the Sandia Corporation [55] and the Los Alamos Scientific Laboratory [59].

In the second technique, black-and-white film is used in the camera. Again, three separate pictures are generated for each frame, each picture corresponding to one of the primary colors. After the black-and-white film has been developed, an optical house combines the images optically through appropriate filters onto color film. Since no modification of the microfilm recorder is required, this technique is more commonly used.

INTERACTIVE GRAPHICS

Admittedly, the animator is at a disadvantage when operating in a batch-processing environment. Communicating pictorial information to the computer by means of paper tape and punched cards is awkward and tedious. Also, the animator prefers an immediate response from the computer so that he can react in real time to the images he has created.

In an interactive graphics environment the animator views the frames of his movie as they are generated by the computer. Through use of either a light pen or an electronic stylus and tablet, he inputs graphical information by drawing the images as he would with pencil and paper. To manipulate the display, he may point with his pen, turn a knob, or type a message on the typewriter. The computer then acts on the instructions, modifying the display. The interaction is completely dynamic with the computer generating new images almost instantaneously.

Because of the considerable expense associated with interactive graphics systems, relatively few are currently in existence. Thus, most of the computer animation being carried out today is accomplished via the batch-processing mode of operation. Significantly, much excellent work is now being done by educators using batch processing. Nevertheless, there is reason to believe that in the next several years interactive animation systems will become more widely available to educators through the combination of time-shared computer systems and inexpensive CRT terminals.

Interactive graphics makes it possible to design animation systems expressly for the animator. In an abstract of an invited paper for the 1971 Purdue Symposium on Applications of Computers to Electrical Engineering Education [74], Ron Baecker states, Recent work has made possible the on-line specification of a movie through sketching at an interactive graphics console. The animator 'doodles through time,' changing the movie with a single sketch or action, then immediately views the result in a real-time playback. Genesys [73], [75], a prototype system embodying this philosophy, has been built and tested. A film about Genesys suggests that the effective use of such an environment allows a spontaneity never before achievable in the history of animation.

The power of the interactive graphics environment is not merely the facilitating of a totally preconceived film, but the providing of a rich exploration space that both facilitates and refines conception. Thus, interactive animation systems are properly viewed as subsets of rich interactive exploration systems, systems which can be used both in research and in teaching.

Computer Image Corporation has also addressed itself to the problem of interfacing the artist with the computer. In an abstract of another invited paper submitted to the 1971 Purdue Symposium [87], Francis Honey writes:

Caeser [85], [86], [104] is such an approach. Caeser is not a program. It is a whole new concept of computer, utilizing digital, analog and video techniques. Caeser accepts drawings created by an animator, using his skills in a familiar way. Then by manipulation of a set of controls, an operator can produce full animation of the character. The resultant animation appears complete and live on a color TV monitor, where the animator can view the animation and modify it to suit his wishes. The computer enables an animator to direct his characters like they were alive on stage.

The General Electric Company has developed a visual simulation system in which full color perspective images of solid objects can be generated in real time using a color television display tube [92]. The system is not interactive in the usual sense in that the environment to be simulated is programmed off-line and may require several weeks of programming effort, depending upon the complexity. Once the environment has been stored in computer memory, an operator, seated in front of the display, can direct himself at will through the environment in real time by moving a joy stick and turning the knobs. In this way the G.E. system has realistically simulated airplanes landing at an airport, cars moving along a highway, spaceships docking in space, and pedestrians viewing both the inside and outside of various buildings as they walk along a city street.

Other excellent interactive animation systems have been developed at Ohio State University [79], the University of Pennsylvania [78], IBM [81], [88], and the Evans and Sutherland Computer Corporation [39].

COMPUTER ANIMATION RESOURCES CENTER (CARC)

The National Science Foundation, recognizing the potential of computer animation in research and education, funded a grant to permit exploration of the concept of a resources center in computer animation and to make recommendations concerning its implementations. In a preliminary report [1], the advisory committee, chaired by Lud Braun of the Polytechnic Institute of Brooklyn, outlined the following possible functions that could be performed by a computer animation resources center.

1. Provide for the processing of magnetic tapes into film for faculty and students. This provision could be made either by an on-site machine or by arrangement with commercial service bureaus.
2. Provision of film services such as preparation of film-loop cartridges, color work, reduction prints, sound tracks, additional copies, etc.
3. Animation software service. This should include collection and evaluation of existing software, provision of a software library, development and standardization of new software that is strongly people-oriented so that non-expert programmers (such as most faculty people) may develop films easily.
4. Provision of filmic and programming consulting services. This would include assistance in getting neophytes started.
5. Presentation of seminars, short courses, and summer residency programs to train faculty in the uses of the medium.
6. Act as a clearing house for information on computer animation.
7. Repository for educational computer-animated films. This might be done in catalog form with some comment included on level of audience, content, quality, source, etc. The resources center also could establish a circulating film library.
8. Generation of newsletters for dissemination of information.
9. Missionary work for computer animation (presentation of papers at technical meetings, addressing groups, development of sample films, etc.).
10. Provision of support for research-related activities, as well as educationally oriented ones.
11. Coordination of activities among universities that are active in the field.
12. Provision of seed money to assist a small number of promising individuals in the early phases of their work in computer animation. Here, the resources center should be the prime contractor, subcontracting to and controlling new ventures. The center should be able to hire consultants to work with the subcontractor. In this way, seeding will be an educational process.
13. Maintenance of familiarity with existing and developing graphics hardware and techniques. This could be done most effectively if some research and development activity were included among the responsibilities of the center.
14. Establishment of guidelines and standards to be followed by service bureaus.
15. Development of a user's handbook that includes information about film specifications, do's-and-don'ts, pitfalls discovered by others, cameras, etc.

The above functions are not listed in order of importance. Some must be provided for from the outset, while others may be classified as desirable functions for some time in the future.

HOW TO GET STARTED

An attractive feature of computer animation is that one need not be a computer expert in order to be a computer animator. All that is really needed is the availability of a computer and the willingness to try. The best way to get started is to contact someone already involved. Computer animators are an enthusiastic breed ready to talk about computer animation to anyone ready to listen. The beginner should not hesitate inquiring at his own computing center since most faculty members are apt to be unaware of the efforts in computer graphics that may be going on at their own universities.

Recommendations for getting started will vary depending on the equipment available at the beginner's home institution and the objectives in mind. Basically, very little is needed in the way of equipment. Computer-animation programs that operate in the batch-processing mode are available without charge. Although a Cal-Comp plotter is desirable for debugging purposes, the line printer can also be used. Several places such as the Polytechnic Institute of Brooklyn, M.I.T., and Kaye Instruments provide microfilm services at reasonable cost. Additional film work, such as the addition of color and sound, can be sent to commercial optical laboratories. Computer animators are generally aware of the ongoing activity in computer animation and once contacted will very likely be able to direct the beginner to the proper place and person for assistance. If the beginner is interested in learning at a graphic console, it may even be possible to arrange for a visit of several months to a computer animation facility having that capability.

Cost is again a variable quantity. The major expenses usually arise from salaries and computing time. These can vary from $100-$500 per minute of projected film and depend upon the complexity of the images being generated. The microfilm recorder and film processing charges generally average less than $50 per minute of completed film. If salaries and computing time do not represent hard dollars, the entire process is quite inexpensive.

The time and effort required to produce a 2- or 3- minute film clip should not be minimized. Preparing a suitable film script may require several weeks of effort and the programming, when done intermittently on a part-time basis, may extend over several months. On the other hand, a beginner with a completed script working full time at a computer animation facility having the microfilm recorder may be able to produce a short film clip in one week's time.

The essential point is that little equipment and no previous experience are needed. Computer animators are willing to assist others in getting started and, in fact, many have become involved in just this way. If a person has a strong desire to produce a computer-generated film, the chance for success is good, provided he is willing to ask for help and is able to devote the time and effort required.

CONCLUSION

Computer animation is, indeed, an exciting new tool for educators. Why not give it a try?

ACKNOWLEDGMENT

Much of the material reported in this paper was compiled from several surveys sent to people actively involved in computer animation. Many excellent efforts have undoubtedly been overlooked. The author thanks those who replied to the surveys and apologizes for that material which was unintentionally omitted.

BIBLIOGRAPHY OF COMPUTER ANIMATION PUBLICATIONS

General Interest

[1] Braun, Feasibility study of a resources center in computer animation, A preliminary report, UAIDE 1969, 177-184.

[2] Citron and Whitney, CAMP - Computer Assisted Movie Production., 1968 FJCC, vol 33, 1968, 1299-1305.

[3] Cralle and Michael, A survey of graphic data processing equipment for computers, Design and Planning, no 2 New York: Hastings, 1967, 155-176.

[4] Csuri and Shaffer, Art, computers and mathematics, 1968 FJCC vol 33, 1968, 1293-1298.

[5] East, Computer animation-a review of the state of the art, Ind Photography, vol 16, no 3, Mar 1967.

[6] Fetter, Computer graphics, in Design and Planning, no 2 New York: Hastings, 1967, 15-24.

[7] Fetter, Computer Graphics in Communication, New York: McGraw-Hill, 1965.

[8] Friesen, A professional animator looks at computer animation,, UAIDE, 1969, 187-193.

[9] Knowlton, Computer-produced movies, Science, vol 150, Nov 1965, 1116-1120.

[10] Knowlton, Noll, Sinden, Movies from the computer, Symposium on the Human Use of Computing Machines, Bell Tel Lab, Murray Hill, June 20-21, 1966.

[11] Noll, Human or machine: A subjective comparison of Piet Mondrian's 'composition with lines' and a computer-generated picture, Psychol Record, vol 16, no 1, Jan 1966, 1-10.

[12] Noll, Computers and the visual arts, in Design and Planning, no 2 New York: Hastings, 1967.

[13] Penderghast, 1968 UAIDE Computer Animation Committee Year-End Report, 72pp.

[14] Rockman and Mezei,The electronic computer as an artist," Canadian Art vol XXI, no 6, Nov-Dec 1964, 365-367.

[15] Sinden, "Synthetic cinematography," Perspective, vol 7, no 4, 1965, 279- 289.

[16] Vanderbeek, New talent the computer, Art in America, Jan-Feb 1970, 90-96.

[17] Weiner, 1969 UAIDE Computer Animation Committee Year-End Report, 80pp.

[18] Weiner, 1970 UAIDE Computer Animation Committee Year-End Report, 87pp.

[19] Winkless and Honore, What good is a baby? 1968 FJCC vol 33 1307-1315,

[20] Zajac, Film animation by computer. New Scientist, vol 29, Feb, 1966, 346-349.

[21] Zajac, Motion picture animation, in Computer Graphics, 199-205.

Movie Languages for the Batch-Processing Environment

[22] Alexander and Huggins, User's Manual on PMACRO, Elec Eng, Johns Hopkins Univ,1967.

[23] Anderson, A list processing system for effectively storing computer animated pictures, UAIDE 1968, 205-219.

[24] Burness, Elekman, Fischetti, Maurer, PIB basic graphic routines, : UAIDE, 1967, 246-257.

[25] Gattis, The SOLIDS animation program, UAIDE 1968, 197-204.

[26] Hopgood, GROATS, A graphic output system for Atlas using the SC4020,, UAIDE 1969, 401-410.

[27] Huggins, Film animation by computer, Mech Eng, vol 89, Feb 1967, 26-29.

[28] Knowlton, A Computer Technique for Producing Animated Movies, 1964 SJCC, vol 25, 67-87.

[29] Knowlton and Cherry, Fortran IV BEFLIX, UAIDE 1969, 411-431.

[30] Knowlton, A language for abstract designs and movies, UAIDE 1970.

[31] Sarno, The polygraphics software package - A summary of its features, UAIDE 1968, 402-409.

[32] Weiner and Anderson, A computer animation movie language for educational motion pictures, 1968 FJCC, vol 33, 1968, 1317-1320.

[33] Weiner, The Syracuse University computer animation programming languages for generating educational films, 1971 Purdue Symposium Application Computer Elec Eng Educ, Apr 1971.

Special Techniques

Perspective Drawings:

[34] Calvert, Projections of multidimensional data for use in man-computer graphics, 1968 FJCC vol 33, 227-231.

[35] Noll, Computer animation and the fourth dimension, 1968 FJCC vol 33, 1279-1283.

[36] Noll, Stereographic projections by digital computer, Computers and Automation vol 14, May 1965, 32-34.

[37] Noll, Computer-generated three-dimensional movies, Computers and Automation, vol 14, Nov 1965, 20-23.

[38] Noll, Computer technique for displaying N-dimensional hyper objects, CACM vol 10, Aug 1967, 469-473.

[39] Sutherland, Perspective views that change in real time, UAIDE 1969,299-310.

[40] Zajac, Computer-made perspective movies as a scientific and communication tool, CACM, vol 7, Mar 1964,169-17.

Hidden-Line Removal and Shading:

[41] Appel, Some techniques for shading machine renderings of solids, 1968 SJCC, vol 32, 37-45.

[42] Bakis, Improved gray scale plotting through combined continuous and halftone techniques, UAIDE 1970,

[43] Behler and Zajac, "A generalized window-shield routine," UAIDE 1969, 351-388.

[44] Davis, Nagel, and Guber, A model making and display technique for 3-D pictures, UAIDE 1968, 47-72.

[45] Dwyer, Windows, shields, and shading, UAIDE 1967, 258-276,

[46] Freeman, Loutrel, An algorithm for the solution of the two-dimensional hidden line problem, IEEE Trans Electron Comput vol EC-16, Dec 1967, 784-790.

[47] Loutrel, An algorithm for eliminating the hidden lines in computer-drawn polyhedra, UAIDE 1968, 421-440.

[48] Luh and Krolak, A mathematical model for mechanical part description, CACM, vol 8, Feb 1965, 125-129.

[49] Romney, Computer assisted assembly and rendering of solids, PhD dissertation, Dep Elec Eng, Univ Utah, Aug 1969.

[50] Stephenson and Burton, Halftone images in computer animation, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr, 1971.

[51] Warnock, A hidden surface algorithm for computer generated halftone pictures, Univ Utah, Computer Science Tech Rep 4-15.

[52] Watkins, A hardware compatible algorithm for generating visible surfaces from 3-dimensional data, UAIDE 1969, 389-400.

[53] Weiss, Be-vision, JACM vol 13, Apr 1966, 194-204.

[54] Wylie, Romney, Evans, and Erdahl, Half-tone perspective drawing by computer, 1967 FJCC vol 31, 1967.

Color:

[55] Hendricks, Application of color development for the S-C 4020, UAIDE 1967, 306-308.

[56] Lamar, A technique for producing color pictures from black-and-white negatives, UAIDE 1969, 289-298.

[57] Lamar, The use of SD-4060 produced microfilm output in pseudo-color transformations, UAIDE 1970.

[58] Rieber, Gazley, and Stratton, Pseudo-color processing of electronic photographs, UAIDE 1967, 88-110.

[59] Shannon, Buckner, Program controlled color computer graphics, UAIDE 1970.

Miscellaneous:

[60] Citron, An algorithm for curve generation, UAIDE 1968, 221-233.

[61] Fischette, Save it, routines for saving, and regenerating S-C 4020 records, UAIDE 1967, 277-281.

[62] Gattis, Character animation and related techniques using a digital computer, UAIDE 1970.

[63] King, Noll, Berry, A new approach to computer-generated holography, UAIDE 1969, 343-348.

[64] Lary, Vector, A vector language embedded in Fortran, UAIDE 1967, 182-190.

[65] Meily, Davis, CAMP-computer animated movie procedures, UAIDE 1967, 23-33.

[66] Nelson, Increasing the flexibility of an SD-4020 installation, UAIDE 1970.

[67] Nelson, Producing sounds for your animated movies, UAIDE 1970.

[68] Robbins, Visual sound, UAIDE 1968, 92-96.

[69] Rosenfeld, Nagel, A technique for speeding up and improving sequences in motion pictures, UAIDE 1970.

Interactive Graphics

[70] Anderson, Generating computer animated movies from a graphic console, UAIDE 1970.

[71] Anderson, An on-line facility for the generation of computer animated educational films, Computer Graphics '70, Brunel, Apr 1970.

[72] Appel, Stein, Landstein, The interactive design of three-dimensional animation, UAIDE 1970.

[73] Baecker, Picture-driven animation, 1969 SJCC vol 34 1969, 273-288.

[74] Baecker, Interactive systems for educational exploration and movie-making, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[75] Baecker, Interactive computer-mediated animation, PhD dissertation, MIT, 1969.

[76] Bernstein, An interactive general purpose computer animated two dimensional movie system with real time viewing capabilities, implemented on a small machine, Moore School of Elec Eng, Univ Penn, Internal Report.

[77] Cohen, Lee, Fast drawing of curves for computer display, in 1969 SJCC vol 34, 297-307.

[78] Carr, Loulter, Johnson, Interactive movie making, UAIDE 1970.

[79] Csuri, Real-time film animation, UAIDE 1970.

[80] Deily, New principles for producing computer animated motion pictures, Moore School of Elec Eng, Univ Penn, Internal Report.

[81] Fernsier, Volence, Artist-computer interactive animation system. UAJDE 1969, 311-330.

[82] Gracer, KARMA: A system for storyboard animation, UAIDE 1970.

[83] Greenberg, Curve fairing on a graphic device. UAIDE 1968, 234-250.

[84] Hayes, A growing machine based computer animation system, Moore School of Elec Eng, Univ Penn, Internal Report.

[85] Honey, Computer animation - A new look, UAIDE 1968, 97-106.

[86] Honey, Television techniques in computer animation, UAIDE 1969, 331-342.

[87] Honey, Computer animated episodes by single axis rotations, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[88] Junker, Rose, Interactive computer animation, UAIDE 1970.

[89] Katzen, A conceptual three-dimensional camera for computer animation, Moore School of Elec Eng, Univ Penn, Internal Report.

[90] Lee, A class of surfaces for computer display, 1969 SJCC, 309-319.

[91] Mehring, Interactive graphics in data processing, IBM System Jnl vol 7 nos 3 and 4, 1968, 145-396.

[92] Rougelot, Wild, Schumaker, Computer animation on the G. E. visual simulation facility, Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[93] Stein, Appel, The interactive design, placement and animation of threedimensional objects, Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[94] Sutherland, Computer displays, Sci Amer, June 1970, 56-82.

[95] Talbot, Animator-A system for using the DEC-338 as an input terminal for movie making, Moore School of Elec Eng, Univ Penn, Philadelphia, Internal Report.

[96] Yarbrough, Experience with CAFE, A new on-line computer animation system, UAIDE 1968, 31-45.

Educational Applications

[97] Black, Ogborn, Hopgood, Chance and thermal equilibrium, UAIDE 1969, 225-244.

[98] Blum, Production and use of single concept films in physics teaching, Commission on College Phys Univ Maryland, College Park, 1967.

[99] Blum Notes on 'Image methods in electrostatics' (A computer animated film), Amer J Phys vol 36, 1968, 412-417.

[100] Cornwell, Problem simulation in motion picture films for intuitive learning, UAIDE 1968, 307-313.

[101] Deily, Electromagnetic fields and waves, part I: Transmission lines, PhD dissertation presented to the Moore School of Elec Eng Univ Penn.

[102] de Rosnay, Levinthal, Computer animated films: New visual aids in the teaching of biochemistry, Proc 7th Nat Biomed Sci Inst Symp, Ann Arbor, May 1969, 134-138.

[103] Goldin, Searl, Bregman, Guidone, Brusselars, A computer animated color film on some concepts in introductory quantum mechanics, UAIDE 1968, 187-195.

[104] Honey, Computer techniques in educational films, UAIDE 1969, 215-224.

[105] Huggins, Educational pantomimes, presented at the Symp on Human Use of Computing Machines, Bell Tel Lab, Murray Hill, June 20-21, 1966.

[106] Huggins, Entwisle, Computer animation for the academic community, in 1969 SJCC vol 34, 623-627.

[107] Levinthal, Molecular model building by computer, Sci Amer, vol 214, 1966, 212.

[108] Lieb, Problem solving: A computer generated educational flm, Moore School of Elec Eng, Univ PennInternal Report

[109] Martin, Application of computer animation to educational films on fields, waves, and lasers, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[110] Max, Computer animation for mathematical flms, UAIDE 1969, 245-252.

[111] Max, Computer animation of smooth surfaces, UAIDE 1970.

[112] Melcher, Complex waves. IEEE Spectrum, vol 5, Oct 1968, 86-101.

[113] Michael, Nillson, The development of an educational computer animated movie -'The convolution integral, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[114] Phillips, Geister, Application of a graphics display terminal to engineering laboratory courses, UAIDE 1969, 197-213,

[115] Sarno, Some computer animated films illustrating aspects of circuit behavior, in Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971,

[116] Schwartz, Taylor, Computer displays in the teaching of physics. 1968 FJCC vol 33, 1285-1292.

[117] Schwartz, The computer-generated film facility of the education research center, Educ Res Cen, Apr, 1970.

[118] Weiner, A computer animated movie illustrating the response of a resonant system to a frequency step, Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[119] Willson, Computer generation of electrical engineering educational films, Proc 1971 Purdue Symp Applic Comput Elec Eng Educ, Apr 1971.

[120j Zajac, Computer animation: A new scientific and educational tool, J Soc Motion Pict Telev Eng, vol 74, Nov 1965, 1006-1008.

[121] Zajac, The hourglass instead of the funnel in educational technology, Educ Technol, 1969.

Scientific Applications

122] Bernboltz, Pretesting environments: The use of computer displays in environmental pretesting, UAIDE 1967,40-55.

[123] Gott, Kibert, Bowyer, Nevatt, Teaching heart function - One application of medical computer animation, 1969 SJCC, vol 34, 637-647.

[124] Harlow, Shannon, Welch, Liquid waves by computer, Science, vol 149, Sept 1965, 1092.

[125] Kelly, Computer animation in the vibration analysis of a nonuniform beam, UAIDE 1969, 271-287.

[126) Noll, Computer graphics in acoustics research, IEEE Trans, Audio Electroacout, vol AU-16, June 1968, 213-220.

[127] Sondhi, Computer movies of wavefront motion, J Acoust Soc Amer, vol 42, Nov 1967, 1210.

[128] Washington et al. The application of CRT contour analysis to general circulation experiments, Bull Amer Meteorol Soc, vol 49, Sept 1968, 882-888.

[129] Woodham, Graphical computer modeling and simulation techniques, UAIDE 1969, 255-269.

BIBLIOGRAPHY OF COMPUTER ANIMATION FILMS

[130] Anderson, Integration over a solid of revolution, 5-min, 16-mm black-and-white silent film.

[131] Anderson, Variable speed walkway, 5-min, 16-mm black-and-white silent film.

[132] Anderson, The game of chess, 8-min, 16-mm black-and-white silent film.

[133] Anderson, Weiner, CAMP-computer aided motion pictures, 11-min, 16-mm black-and-white silent film.

[134] Baecker, GENESYS; An interactive computer-mediated animation system, 17-min, 16-mm color sound film.

[1351 Blum, Image methods in electrostatics, 4-min, 16-mm or 8-mm color silent film-loop.

[136] Bork, Quantum mechanical harmonic oscillator, 4-min, 8-mm or 16-mm black-and-white silent film.

[137] Brock, Quadruped locomotion, 3-min, 16-mm black-and-white silent film.

[138] Cornell, Stresses in pressure vessels, 7-min, 16-mm black-and-white silent film.

[139] Davis, Selfridge, Twinkle, a computer animation study of temporal integration in the human visual system, 8-min, 16-mm black-and-white sound film.

[140] D de Fontaine, Nucleation from the vapor on a substrate at different temperatures, 10-min, black-and-white silent film.

[141] Deily, Electromagnetic fields and waves, part I: Transmission lines, 40-min, 16-mm color sound film.

[142] de Rosnay, Biosynthesis of steroids, 16-mm black-and-white silent film.

[143] de Rosnay, Biosynthesis of steroids, 5: 30-min, 16-mm black-and-white silent film.

[144] de Rosnay, Catalysis by a co-enzyme, 4:45-min, 16-mm black-and-white silent film.

[145] de Rosnay, Amino acids and proteins, 5:45-min, 16-mm black-and-white silent film.

[146] de Rosnay, Barry, Alpha helix formation, 3-min, 16-mm black-and-white silent film.

[147] de Rosnay, Barry, Small molecules, 4: 15-min, 16-mm black-and-white silent film.

[148] de Rosnay, Barry, Structure of proteins, 9:30-min, 16-mm black-and-white silent film.

[149] de Rosnay, Barry, Chempak, 9-min, 16-mm black-and-white silent film.

[150] Fetter, Second man, 10-min, 16-mm color silent film.

[151] Fetter, Engine removal. 10-min, 16-mm color sound film.

[152] Fetter, Carrier landing, 10-min, 16-mm color sound film.

[153] Fetter, Film report, Computer graphics, 10-min, 16-mm color silent film.

[154] Fetter, Film report. Computer graphics, 10-min 16-mm color silent flm.

[155] Friedman, Vector kinematics, 16-min, 16-mm black-and-white sound film.

[156] Goldin, Quantum collisions, 15-min, 16-mm color sound film.

[157] Goodman, Computer generated art, 8-min, 16-mm black-and-white silent film.

[158] Hobbie, Fourier series, black-and-white or color silent film-loop.

[159] Hobbie, Velocity from position, 3-min, 16-mm black-and-white silent film. T

[160 Hobbie, Position from velocity, 4-min, 16-mm black-and-white silent film.

[161] Hobbie, Halberg, Rhythmometry in biology and medicine, 5-min, 16- mm black-and-white silent film.

[162] Hohl, Dynamics of disk galaxies, 6-min, 16-mm color sound film.

[163] Hopgood, Chance and thermal equilibrium, 20-min, 16-mm black-and-white silent film.

[164] Huggins, Weiner, Harmonic phasors, 7-min, 16-mm black-and-white silent film.

[166] Julesz, Bosche, Studies with random texture, 4-min, 16-mm black-andwhite silent film.

[167] Junker, Rose, Artist-computer interactive animation, 3-min, 16-mm black-and-white silent film.

[168] Kaitz, Displays of structural systems, 7-min, 16-mm color silent film.

[169] King, Movies from computers: An interim report, 20-min, 16-mm blackand-white sound film.

[170] Knowlton, A computer technique for the production of animated movies, 17-min, 16-mm black-and-white silent film.

[171] Knowlton, LS: Bell Telephone Laboratories low level linked list language, 16- min, 16-mm black-and-white sound film.

[172] Knowlton, LS-part II, An example of LS programming, 32-min, 16-mm blackand-white sound film.

[173] Kruskal, Multidimensional scaling, 4-min, 16-mm black-and-white silent film.

[174] Liang, On-line cartooning, 1-min, 16-mm black-and-white silent film.

[175] Liang, A documentary on generating a global map, 5-min, 16-mm blackand-white silent film.

[176] Liang, Optical enhancement of computer animated footages, 1-min, 16-mm color sound film.

[177] Liang, Koenig, Introducing interactive graphics system to Norman McLaren -'Birdlings' , 5-min, 16-mm black-and-white silent and sound film.

[178] Lincoln Lab, Imaging radio sources with a digital computer, 16-mm black-and-white sound film.

[179] Luby, Laser light, 20-min, 16-mm color sound film.

[180] Lumley, Eulerian and Lagrangian descriptions, 27-min, 16-mm black-andwhite sound film.

[181] Lumley, Eulerian and Lagrangian descriptions in Fluid Mechanics 31-min, 16-mm black-and-white sound film.

[182] Lummis, Simulated basilar membrane motion (2D), 11-min, 16-mm blackand-white silent film.

[183] Lummis, Noll, Simulated basilar membrane motion (3D), 5-min, 16-mm, black-and-white silent film.

[184] McCumber, Dynamic field distributions in Gunn-effect devices, 12-min, 16-mm black-and-white silent film.

[185] Melcher, Complex waves I: Propagation, evanescence and instability, 26- min, 16-mm black-and-white sound film.

[186] Melcher, Complex waves II: Instability, convection and amplification, 23-min, 16-mm black-and-white sound film.

[187] Meyer, Landish, The angular momentum of circularly polarized radiation, 18-min, 16-mm black-and-white sound film.

[188] Noll, Hyper objects. 5-min, 16-mm black-and-white silent film.

[189] Noll, 4D-Hyper movie, 5-min, 16-mm black-and-white silent film.

[190] Noll, 4-dimensional hypercube, 3-min, 16-mm black-and-white silent film.

[191] Noll, Computer-generated ballet, 3-min, 16-mm black-and-white silent film.

[192] Rieber, POGO, 20-min, 16-mm color sound film.

[193] Shaffer, Hummingbird, 10-min, 16-mm black-and-white silent film.

[194] Shannon, Computer fluid dynamics, 23-min, 16-mm color sound film.

[195] Shepard, Zajac, A pair of paradoxes, 2-min, 16-mm black-and-white sound film. Sound track is computer produced.

[196] Sinden, Force, mass and motion, 10-min, 16-mm black-and-white sound film.

[197] Sinden, Inscribed right angle, 3-min, Super-8 silent color filmloop.

[198] Stephenson, Continuous tone motion picture, 20-min, 16-mm black-andwhite silent film.

[199] Stromberg-Datagraphix, A world orbit display using the S-D 4020, 2-min, 16-mm black-and-white silent film.

[200] Sztaba, Vegetable soup, 3-min, 16-mm black-and-white sound film.

[201] Van Der Beek, Poem-field No 1, 5-min, 16-mm color sound film.

[202] Van Der Beek, Poem-field No 2,> 7-min color sound film.

[203] Van Der Beek, Poem-field No 3, 10-min, 16-mm color sound film.

[204] Van Der Beek, Poem-field No 4, 10-min, 16-mm black-and-white sound film.

[205] Van Der Beek, Poem-field No 5, 6-min, 16-mm, color sound film.

[206] Van Der Beek, Poem-field No 7, 5-min, 16-mm color sound film.

[207] Van Der Beek, Collideoscope, 5-min, 16-mm color sound film.

[208] Van Der Beek, Knowlton, Man and his world, 1-min, 16-mm color sound film.

[209] Van Duzer, Wave velocities, dispersion, and the omega-beta diagram, 12-min, 16-mm black-and-white sound film.

[210] Weiner, Huggins, Response of a resonant system to a frequency step, 12-min, 16-mm black-and-white silent film.

[211] Weiss, Photo dissociation of ICN, 6-min, 16-mm color sound film.

[212] Wiley, Satellite motion simulation, 2-min, 16-mm black-and-white silent film.

[213] Zabusky, Deem, Kruskal, Formation, propagation, and interaction of solutions in non-linear dispersive media, 25-min, 16-mm black-and-white silent film.

[214] Zajac, Two-gyro, gravity gradient attitude control system, 7-min, 16-mm black-and-white silent film.

[215] Zajac, Two-gyro gravity-gradient attitude control system, 4-min, 16-mm black-and-white sound film.