Editor - in - Chief ' s Introduction The Human - Machine Connection Selections from the Third Annual NCGA Conference

The goal of the National Computer Graphics Association is "to increase the productivity of industry and management in the United States through the use of computer graphics." The first four articles in this special issue, based on papers presented at NCGA '82 last June, reflect the association's continuing commitment to that goal. At the same time, they reflect an awareness-intensified since NCGA '81 -of the crucial role of human beings in putting to work the full potential of computer graphics technology. Thus, we find in these articles several variations on the human-machine theme with emphasis on human factors, ease of use, and interactive environments. The proliferation of computer systems in the workplace means that a great many people inexperienced and unfamiliar with computers must quickly learn to make effective use of these machines. In our first article, Kenneth Lodding proposes that an iconic interface-that is, the provision of user commands in the form of images-can overcome the difficulties of traditional command languages. He explains the principles of communications, cognition, and design that must underlie a system of iconic man-machine communication. Another graphics interface, also involving icons, is the subject of Albert Stevens, Bruce Roberts, and Larry Stead, who describe a prototype instructional system used by a US Navy training course in steam propulsion system operation. The "Steamer" model gives trainees an interactive simulation of hands-on practice in operating complex equipment-without the difficulty, risk, and expense involved in actual practice. Interactive computer graphics promises great potential for increased productivity in another environment-the energy exploration field. Thomas Gardner and H. Roice Nelson, Jr., point out that interactive systems have now reached the level of technological sophistication required by geophysicists, geologists, and petroleum engineers in their search for oil and gas. The authors describe recent developments in the use of interactive techniques for the processing and interpretation of seismic data. While our first article explains how graphic images can ease the computer-user's access to the system, our concluding NCGA article looks at the displayed output of the system-particularly maps, graphs, charts, and diagrams. Using cartographic examples, George McCleary, Jr., presents a graphic "vocabulary"-the visual variables at work in the graphic presentation of data. He explains the principles of human perception that determine the effectiveness of symbolized information displays.