Animated mapping is the application of animation, either a 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.
framed|Animation of the 2004 Indonesian tsunami
History
The concept of animated maps began in the 1930s but did not become more developed by cartographers until the 1950s. 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.
With the development of computers in the 1960s and 1970s, animation programs were developed allowing the growth of animation in mapping. Waldo Tobler created one of the first computer-generated map animations, using a 3-D computer-generated map to portray population growth over a specified time in Detroit. Hal Moellering created another animated map in 1976 representing a spatiotemporal pattern in traffic accidents.
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.
Animation on maps can be mainly divided into two types: temporal and non-temporal.
Temporal map animation
thumb|Animated dot density map of COVID-19 cases in Connecticut between March 21, 2020 and May 21, 2020
Temporal map animation shows the ongoing gradual changes over time. Temporal maps can also be termed animated timeline maps and can be a useful reference to examine the changes ongoing on each step and analyze the progression occurring gradually as time passes.
There are many purposes which temporal animation might serve to depict: displaying and analyzing geographic patterns, meteorological events, climate, natural disasters, and other multivariate data.
Animated mapping of history
Animated mapping is extensively used in the construction of animated maps to depict historical events in a cartographic environment, particularly in the subdiscipline of Historical geographic information system. These were one of the first applications of such maps, documented in Waldo Tobler's 1970 paper.
Importance of legend in temporal maps
As in the case of static maps, it would be useful if temporal maps could also be provided with proper legend. Legends for temporal maps should not only tell the time but also let users travel over time. Various manipulations such as traveling to a certain point in time, selecting focus level, etc. should be allowed to enhance user-friendliness.
Using legend in the temporal map will answer important questions related to the entity's existence (if?), the entity's location (when?), time intervals (how long?), temporal texture (how often), the speed at which change takes place (how fast?), and the order of change (what order?).