NewsMaps - Mappa. For more information about this subject, the following resources are recommended. See the USGS online booklet on Topographic Mapping for a nice introduction to the topic. They are also among the most map-like of information maps, borrowing literally and liberally from the cartographer's toolbox. Solutions developed for mapping relief include the use of contour lines and elevation shading.
Contour lines trace areas of equal height and they are drawn at regular elevation intervals.
To distinguish different contours they can be shaded with an appropriate gradation of colors that give the visual impression of changing elevation. Both contour lines and elevation shading are successfully employed by NewsMaps to provide a terrain that appears almost three-dimensional on a flat computer screen. These maps are, of course, using the hills and valleys metaphorically to represent the volume of textual information. The spatial properties of location and elevation in the maps are used to encode key characteristics of the form and structure of the information space in a single visual snapshot. Intuitively, the higher the mountain, the greater the number of news stories.