Geographic Information Systems: An Introduction, 3rd Edition

16.4 Limitations and Potentials of GIS in Cartographic Communications

Practical solutions

The ability of a GIS facility to employ cartographic variables is determined primarily by the constraints imposed by the software systems on its screens and plotters. These programs usually contain predefined symbol libraries (Figure 16.6). Users may often define their own symbols, either by digitizing symbols drawn or printed on paper or by using software tools to construct their own symbols (Figure 16.7). As shown in Figure 16.6, a large selection of different styles of lines, symbols, and text lettering is now available.

Normally, GIS will support printouts of defined attribute values, such as measured values and names of measurement stations, or permit attribute values to direct the plotting of selected symbols. The size and color of symbols may be related to the attribute value by checking with a reference (look-up) table (Figure 16.8). Density of symbols or solid colors may be used to indicate phenomena covering areas on a map. For example, colors may be assigned numerical codes, which are entered into the plotting codes for the map polygons, which in turn are activated when the map is plotted. Most GIS facilities support a range of letter fonts, either in basic system software or in plotter programs.

Figure 16.6

Typical symbol library. (© ESRI.)

Raster displays support color assignments ...