1 - Computer graphics: An introduction

Abstract

Generating synthetic images from a computer plays an outstanding role in molecular modeling. Basically, three main types of graphics hardware systems can be distinguished: workstations, microcomputers, and graphics terminals. Workstations, self-governing devices with important storage memory, are often provided with a mathematical coprocessor and dedicated processors to perform graphics operations. Microcomputers are now available with faster clocks, 32 bit processors, mathematical coprocessors, and cards to give enlarged graphic resolution on appropriate display monitors. Graphics terminals have to be connected to a host computer. However, they now offer opportunities for local treatments. Various molecular modeling packages are now available at PC level. However, despite their extended capabilities, PCs still have some difficulties carrying out heavy molecular orbital methods for medium-size molecules. With reduced instruction set computing architecture and more efficient buses, workstations offer ever-increasing power. Graphics terminals integrate more sophisticated output primitives and offer better assistance. Most display devices now use the standard cathode-ray tube (CRT). However, an increasing number of portable terminals are appearing that are provided with a plasma panel display, light-emitting diodes or liquid crystal display. An essential part of all graphic systems is the display processor. Basically, it exploits the digital information from the central processing unit, converting it into analog signals to generate pictures or characters on the display screen and ensuring screen refreshment through a refresh storage area where the picture definition is kept.