ABSTRACT
One of mankind’s first tools with a visual display was the sundial, built more than 3000 years ago in Babylon. Visual displays rely on different physical principles to generate an image, including light emission, transmission, and reflection. Examples from noncomputer displays can be helpful to explain these basic principles and point out relevant advantages and limitations. There are two basic methods for displaying information visually: digital and analog. A digital display uses a discrete spatial structure to display symbols such as characters and icons, whereas an analog system uses a spatially continuous instrument panel for information presentation. Visual displays can be differentiated by means of the spatial dimensionality of the image generated. The simplest way to display information is to rely on only one spatial dimension. A popular approach is to mount the display on a user’s head. Thus the user can work hands-free and is always able to perceive information in his or her field of view.
