Figure 3.1. View of an area at a lake during the summer from the Ecodisc system. The user can "turn" to look in another direction by clicking the radio buttons in the inner part of the compass rose and can "move" to another location by clicking the arrows in the outer part of the compass rose. Clicking on the snow crystal activates movement in time to the winter view in Figure 3.2, as an example of temporal navigation. Copyright © 1990 by ESM, Ltd., reprinted by permission.