GIS: All About Symbols
By Mithu Datta

In geographical information systems (GIS), symbols are ways to identify different map objects using graphics. These symbols may vary in color, size and shape to represent some geographical characteristic.

Maps typically include symbols that represent such features as streets, buildings, streams, and vegetation. These features are represented as points, lines and polygons.

Many features are shown by lines that may be straight, curved, solid, dashed, dotted, or in any combination. The colors of the lines usually indicate similar classes of information: topographic contours (brown); lakes, streams, irrigation ditches, and other hydrographic features (blue); land grids and important roads (red); and other roads and trails, railroads, boundaries, and other cultural features (black), such as Topographic Map Symbols and USGS.

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