Map symbol

A map symbol or cartographic symbol is a graphical device used to visually represent a real-world feature on a map, working in the same fashion as other forms of symbols. Map symbols may include point markers, lines, regions, continuous fields, or text; these can be designed visually in their shape, size, color, pattern, and other graphic variables to represent a variety of information about each phenomenon being represented. Map symbols simultaneously serve several purposes: Declare the existence of geographic phenomena Show location and extent Visualize attribute information Add to (or detract from) the aesthetic appeal of the map, and/or evoke a particular aesthetic reaction (a "look and feel") Establish an overall gestalt order to make the map more or less useful, including visual hierarchy Symbols are used to represent geographic phenomena, which exist in, and are represented by, a variety of spatial forms. Different kinds of symbols are used to portray different spatial forms. Phenomena can be categorized a number of ways, but two are most relevant to symbology: ontological form and dimensionality. When a symbol is representing a property of the phenomenon as well as its location, the choice of symbol also depends on the nature of that property, usually classified as a Level of measurement. Geographic phenomena can be categorized into objects, which are recognizable as a unified whole with a relevant boundary and shape; and masses, in which the notion of boundary and wholeness are not relevant to their identity. Features such as buildings, cities, roads, lakes, and countries are geographic objects that are often portrayed on maps using symbols. Mass phenomena include air, water, vegetation, and rock. These are rarely represented directly on maps; instead, map symbols portray their properties, which usually take the form of geographic fields, such as temperature, moisture content, density, and composition. Dimension The number of spatial dimensions needed to represent a phenomenon determine a choice of Geometric primitive; each type of geometric primitive is drawn with a different type of visual symbol.