Francis J Honey
March, 1971
Journal of the SMPTE
Presented on October 1, 1969, at the Society's Technical Conference in Los Angeles by Francis J, Honey, Computer Image Corp., 2162 South Jason St., Denver, CO 80223.
INTRODUCTION
While increasing effort is being made to employ computers in the drawing of pictures, most attempts are confined to the use of existing digital computers which are generally expensive to acquire and difficult to program. In addition such machines are inherently unable to handle the extremely high data rates necessary for dynamic animation generation with the detail and quality required by a graphic artist. Specialized hybrid computers, designed specifically for artist use, permit the generation of complex animated materials directly at standard cine or TV frame rates. The resultant high-speed, high-quality response to the artist's demands makes the systems well suited to the production of entertainment, educational, commercial and training films and videotapes. The new computers permit the artist to work with familiar tools in a familiar way and yet they permit him instantaneous control of shape, motion and color in a way never before possible.
THE FACT that computer technology has much to offer to the animation world has been known to computer people for some time. The ability to store and recall many facts coupled with the ability to repeat tasks over and over again without boredom would seem to make the computer a much desired assistant in the animation house. However, with the exception of an occasional computer-controlled animation stand and some computer-controlled editing schemes, few computer applications in animation exist outside 1f engineering facilities. There are many ways to explain the lack of computer use by artists but perhaps the main reason is a matter of philosophy.
A common engineering approach to computer animation is: I have a huge computer facility, how can I animate with it? This approach can meet with much success if the desired result is well defined or easily represented mathematically. Unfortunately, artistic creation is seldom well defined beforehand and almost never easily represented mathematically. Computers are not often used by the artist because, in general, the computer fails the artist and simply getting a bigger hammer won't solve the problem.
For effective computer animation the artist requires:
- easy and familiar communication with the computer;
- rapid response to his ideas of shape, motion and color;
- high picture quality and detail; and
- freedom from undue pressures caused by cost, time limits, unfamiliar tools and a hostile environment.
A unique approach to computer design has resulted in a series of hybrid computers well suited to the artist's requirements.
Hybrid Computers
For the purpose of understanding the new computers it is desirable to digress a moment and discuss hybrid computers in general. It is generally known that there are two basic kinds of computers, analog and digital. Risking oversimplification, a digital computer can be said to be composed of a single class of circuit elements which have two states of being on or off or in another way yes or no. By complex ordering and interconnecting of many such devices it is possible to work complex problems of addition, multiplication, integration and so on. Such a machine has great inherent precision because at any instance the answer must be yes or no. There is no room for indecision or uncertainty. On the other hand such a machine is relatively slow, even though the elements may be very fast. because many questions must be asked one after another to solve even a simple addition problem.
An analog machine on the other hand is generally composed of a grouping of numerous dissimilar elements, one for addition, a different kind for multiplication and still another kind for integration and so on. Each of these elements may not only answer yes or no but also maybe. Worse still, the maybe may change with time, temperature and sometimes for seemingly no reason. As a result analog computers suffer from accuracy problems. There is much room for uncertainty. However, because the analog computer consists of many elements that can all work on the same problem simultaneously or in parallel, rather than the iterative or series approach of the digital computer, analog computers are faster for a given state of art than digital computers.
At this point it should be made clear, that there is no conflict between analog and digital computers, in spite of the fact that much conflict exists between analog and digital people. Each approach has strengths and weaknesses. Perhaps an intelligent solution to a problem would suggest a combination of analog and digital techniques. A computer consisting of such a combination is called a hybrid computer. A hybrid computer can use the long-term accuracy of the digital computer and yet make good use of the high speed of the analog computer. Analog techniques are well-suited to communication with the real world, particularly man, while digital techniques lend themselves to accurate long-term memory. Each technique strengthens the other in a properly designed hybrid computer.
Scanimate
Scanimate, a special hybrid computer that bas been designed to serve the needs of artists, is primarily aimed at the graphic artist. The term graphic artist here refers to those artists involved in pictorial communication in a broad sense. The term is not intended to completely eliminate character animation of the Disney sort, but it is applied in an attempt to emphasize the use of print, logos, pictures, abstract forms and areas of moving colors and shapes which are all intended to convey information or emotion. The term includes much of the sort of animation seen in television commercials, as well as many parts of movies such as Disney's Fantasia created many years ago, and even much of the recent movie Yellow Submarine.
Another example could be the excellent special effects for the space-time warp in the movie 2001. Use of Scanimate explicitly excludes character animation of the sort seen in Snow White or Bambi yet it may include simple character animations of the sort used in recent Alka-Seltzer cornmericals. Scanimate came into existence as the result of attempts to apply our philosophy and technology to the problems of the graphic artist. Our early technical capabilities were found to be suitable for graphic animation while at the same time they were inadequate for complex Disney-type character animation.
Description
The block diagram, Fig. 1, will aid a description of Scanimate. It may be noted that television techniques are in use at both input and output. Television techniques are noted for their ability to handle complex picture data. Furthermore television techniques interface well with analog computer techniques, becoming, in fact, an almost perfect communication link between the artist and the computer. The artist prepares drawings using his own well-developed skills. The special TV cameras are used to convert the artwork to electrical signals which can be processed by the hybrid computer. By the use of a TV link the artist is thus able to tell the computer what to animate. The image input to the computer contains not only the elements desired by the artist but the style of the artist is preserved as well - a tremendously important feature to an artist! The initial communication between artist and computer is indeed easy and familiar by this approach.
Fig 1. Scanimate computer system diagram
Figure 2 shows an operator at the computer. Adjustment of controls on the console permits the operator (often the artist himself) to control the computer operation. Operating on the signals from the TV cameras and responding to control settings, the Scanimate computer adds and subtracts, multiplies and divides, integrates and differentiates, takes roots and powers and thereby creates and controls a picture drawn on a cathode-ray tube type X-Y display. At the will of the artist, the pictures prepared by conventional techniques are converted to electrical equivalents which are processed by the computer and reconverted into a new picture on the CRT. The CRT image may be made to go through an almost infinite variety of motions: exploding, zooming (to a point or to vanish), plasticizing, growing, shrinking, pulling through itself, revolving, twisting, squeezing, undulating and more.
Fig 2. Scanimate operations console
Conventional animation-stand effects are as available as totally new special effects. Because of the high speed of calculation made possible by the analog computer portions, the output pictures can be drawn at standard cine rates in spite of great visual detail (see Fig. 3), thus satisfying the artist's need for rapid response to his ideas of shape and motion. Exceptional care in the design of the X-Y CRT display has resulted in a high-quality picture in the output in spite of high picture-frame rates. Graphic artists have long taken the quality obtained by conventional printing schemes for granted. The normally poor graphic quality created by most computer displays is unsatisfactory.
Fig 3. Several examples of imagery produced by Scanimate Note the great visual detail that can be drawn by the process.
The output of the system may be recorded by two means. Scanimate can be made to operate at a rate of 48 frames/s at which it is possible to film the CRT display with a standard cine camera such as a Mitchell 35mm or an Arriflex 16mm operating at 24 frames/s. If both the camera and the computer operate synchronous with the power line it is only necessary to sense the shutter position of the camera to tell the computer when to draw. Black-and-white film is used and multiple passes are colored and combined in the optical lab to produce multicolored films. Although white phosphor on the CRT could be used with filters to produce color directly we have found that higher resolution green phosphors produce higher-quality images and editing in black-and-white film is both easier and cheaper.
The second method of recording output is certainly more exciting and useful to the artist. Scanimate can also be made to operate at 60 frames/s. Referral to Fig. 1 will disclose another TV camera which can be used to view the X-Y CRT display. This is a single Plumbicon camera which is sensitive to gray levels in the display intensity. The camera video output is fed to a special color encoder that converts the signal to an NTSC signal. The NTSC signal is fed to a microwave link which connects the Scanimate output to a local television studio's recording facility.
Figure 4 shows an artist at the control console of the NTSC encoder. A unique feature of this encoder is the method of color selection and control. Five levels of gray are established with sufficient separation to provide graphic quality. Five sets of RBG (Fig. 4) controls are provided, each switched on in turn whenever a corresponding gray level appears in the camera output. An artist is thus able to deliberately and accurately paint each gray level any color and any brilliance (chrominance and luminance) without regard to the colors of any other gray level and without regard to the amplitude of the gray level itself. The resulting flexibility is a delight to an artist. Scanimate with color video output allows an artist to create form, motion and color. It allows him to evaluate his creation, viewing it over and over. It allows him to apply subtle changes to form, motion and color and finally, only when he is happy with the result, does he record his creation on videotape.
Fig 4. Artist at video color control console. Controls immediately above color monitor allow individual control of red, blue and green components for five gray levels in the input video. The final color animated computer output appears on the monitor before the artist.
The Artist
The final artist requirement listed in the introduction indicated a need for freedom from undue pressures caused by cost, time limits, unfamiliar tools and a hostile environment.
Compliance with this requirement is made easier by a design such as Scanimate but how the system is presented to the artist is just as important as the circuit design. Figure 5 is a general view of the Denver Scanimate facility. It is frequently overrun by engineers and is often changed as a new element is added for evaluation and yet care is exercized to make artists feel welcome. The artist must be coaxed to use a computer. Therefore, there are light tables and artist supplies and yet there is a technical flair too.
Fig 5. Overview of Denver Scanimate production facility
Future Considerations
It might be said that Scanimate is the end of the beginning. With color video output, it is a finished, fully operational, computer system created after fifteen years research and development into the needs of artists and into the best ways to satisfy those needs. The system is specialized to the extent that it is directed to the graphic artist. It is perhaps most suited to television commercials or short educational film animations. It can be used effectively for movie and TV titles, and it can even be used to create some limited forms of character animation. However, Scanimate cannot do full character animations.
Full animation of cartoon characters, live on color videotape is the next step in the development of our technology. The first system with this capability is already assembled in prototype form; it will produce color cartoons directly on videotape. The next step will be color cartoons directly on color film for theater use. These systems will make a heavy use of digital computers for editing to enable efficient creation of long productions. But in spite of increasing complexity and cost, the computers will be built with the same philosophy. It's an approach dedicated to making technology available to artists without requiring them to become technologists.