Leonardo

COMMENTS ON THE BOOK COMPUTER ANIMATION Ana Sacerdote de Guthmann* 1. Digital and .analog computers are being used more and more for producing various kinds of art. John Halas has collected in his book Cornputer Anitnatioti [ I] a number of articles by computer experts that describe computer programs of potential assistance to artists who are concerned with animation and graphic artwork but who are not prepared to cope with problems requiring recourse to mathematics. The book provides a large amount of technical information. which is presented clearly. Ample diagrams are given to aid in the description of hardware and software. and a helpful glossary of technical terms is appended. Two basic approaches are considered for making graphic artworks and animated films. In one, the artistic input is in the form of a computer program. Several contributors describe modified computer languages for producing software more suitable for the purpose. Artists do not need to know how to program; they need only to apply a number of simple formulas to call into service the languages stored in the computer as a set of subroutines that comprise the 'software package'. The hardware in most of the cases considered is a microfilm recorder that receives digital information. converts it and records it as images on the film. Some detailed descriptions of such methods are presented in several articles that tend to complement each other. D. D. Weiner and S.E. Anderson present four computer programs, and outline their utility in producing 10-100 film frames in response to only a few commands. F. R. A. Hopgood and D. Ralphs analyze in detail the structure of two of these programs. Kenneth C. Knowlton and W. H. Huggins describe a particular computer language for cinema called 'EXPLOR' that enables the production of certain pictorial and textural effects, and Lillian Schwartz reports on her application of Knowlton's systems for generating images in films. Articles by Maurice Russoff and Frank E. Taylor, Robert Barfield and John V. Oldfield. Tony Pritchett, and Judah Schwartz and Edwin Taylor point out the advantages of using a computer animation technique for making educational films for mathematics or physics teaching and the opportunities that animation offer as an education aid in general. Paul Nelson describes how the effects of zoom, pan, wipe, scissoring, masking. etc. are produced with the technique. In the second basic approach through what is called an iritertrc~riw.srstern, an artist traces lines on a tablet with an electronic pen and the images of the lines appear on a screen as they are being traced. Corrections and changes can be made while the image is still on the screen or after *Artist. VIDT 2004. Buenos Aires. Argentina. (Received 6 Sept. 1976). the image is recalled from storage. Three interactive systems employed in making animated films are described in detail. P. M. Beatts treats one system that avoids repetitious tasks in animation work and that has a large storage capacity in the form of ii series of libraries. N. Burtnyk and M. Wein describe kql~,/i.ritnc ~rnirmtion, for' which only principal drawings must be defined accurately; a computer is instructed to make transitions between them. Ronald Baecker describes a novel system called 'Genesys' in which images are formed by dots. Using this system the animator traces separately the picture of an object (for example. a frog) and a line representing the path of its movement (for example. the frog's hop). The dots delineating the object in the image display are closely spaced. effectively representing continuous lines. Each of the dots delineating the path of motion represents one specific point on the object at locations at successive equal-time intervals. Thus, the faster the motion the greater the distance between the dots. Both Bruce Cornwell, in a lucid analysisof technical and aesthetic aspects of computer animation. and Malcolm Le Grice, in a historical survey of animated art tilms up to the present. compare and criticize the systems described in the book in an effort to detect future trends in computer art. Stephen A. Kallis describes the use ofa small computer to facilitatethe filming of drawings on an cininiution stand, a table on which drawings are placed and above...