In the design of any visual objects, the work becomes much easier if previous designs are utilized. Computer graphics is becoming increasingly important simply because it greatly helps in utilizing such previous designs. Here, "previous designs" signifies both design results and design procedures. The objects designed are diverse. For engineers, these objects could be machines or electronic circuits, as discussed in Chap. 3, ''CA~/CAM. '' Physicians often design models of a patient's organs from computed tomography images prior to surgery or to assist in diagnosis. This is the subject of Chap. 8, "Medical Graphics. " Chapter 7, "Computer Art," deals with the way in which artists use computer graphics in creating beautiful visual images. In Chap. 1, "Computational Geometry," a firm basis is provided for the definition of shapes in designed objects; this is a typical technical area in which computer graphics is constantly making worldwide progress. Thus, the present volume, reflecting international advances in these and other areas of computer graphics, provides every potential or actual graphics user with the essential up-to-date information. There are, typically, two ways of gathering this current information. One way is to invite international authorities to write on their areas of specialization. Usually this works very well if the areas are sufficiently established that it is possible to judge exactly who knows what. Since computer graphics, however, is still in its developmental stage, this method cannot be applied.
