Animated mapping

Animated mapping is the application of animation, either computer or video, to add a temporal component to a map displaying change in some dimension. Most commonly the change is shown over time, generally at a greatly changed scale (either much faster than real time or much slower). An example would be the animation produced after the 2004 Tsunami showing how the waves spread across the Indian Ocean.



History
The concept of animated maps began in the 1930s, but did not become more developed by cartographers until the 1950s (Slocum et al. 2005). In 1959, Norman Thrower published Animated Cartography, discussing the use of animated maps in adding a new dimension that was difficult to express in static maps: time. These early maps were created by drawing "snap-shots" of static maps, putting a series of maps together to form a scene and creating animation through photography tricks (Thrower 1959). Such early maps rarely had an associated scale, legends or oriented themselves to lines of longitude or latitude (Campbell and Egbert 1990).

With the development of computers in the 1960s and 1970s, animation programs were developed allowing the growth of animation in mapping. Walter Tobler created one of the first animations, using a 3-D computer generated map to portray population growth over a specified time in Detroit (Tobler 1970). Hal Moellering created another animated map in 1976 representing a spatiotemporal pattern in traffic accidents (Slocum et al. 2005).

Further development in animated map was stalled until the 1990s due to a lack of animation in academics, financial restrictions on research, and lack of distribution means (Campbell and Egbert 1990). In the 1990s, however, the invention of faster, more efficient computers, compact discs and the Internet solved such problems.

Visual variables
With the growth of animated mapping came the development of guidelines for creating animated maps. Visual variables such as spacing, lightness and shape used for static maps apply. However, in 1991, David DiBiase and colleagues developed visual variables unique to animated maps: duration, rate of change and order. Duration is the unit of time a frame or scene is displayed, affecting the smoothness of the animation. The shorter a frame is displayed, the smoother the animation will appear (Slocum et al. 2005). Smoothness of animation is also a function of the rate of change (Slocum et al. 2005). Order refers to the time sequence in which animation is played out, usually presented in chronological sequence (Slocum et al. 2005). Alan MacEachren extended these visual variables in 1995 to include display date (time at which change is initiated), frequency (number of times identifiable forms are displayed) and synchronization (correspondence of 2 or more time series) (Slocum et al. 2005).

Types of animated maps
Animated maps can emphasize the existence of an occurrence at a location, emphasize an attribute of an occurrence or representing change in the position or attributes of an occurrence (DiBiase 1992). For instance, a flashing symbol may be used to draw the map-reader’s attention to a particular occurrence at one location or multiple location across the map. Maps on the weather channel use animation to emphasize current and predicted paths of hurricanes.

The use of the Internet has allowed animated maps to become interactive. The user can witness representations of changes over time, while manipulating the direction of view, the pace or the parameters of the map displayed (MacEachren 1998).