Keywords: animation, visualization, temporal and non-temporal animation, geo-objects, animation-objects, spatio-temporal patterns
Prof. Michael P. Peterson
Department of Geography / Geology
University of Nebraska at Omaha
Omaha, NE 68182
Animation holds a special place in cartography. Defined as a graphic art that occurs in time, animation is a dynamic visual statement that evolves through change in the display. Early examples of cartographic animation on film and video could not be easily duplicated, transported, or displayed thus severely limiting their distribution and use. The making of these early animations was also time-consuming and expensive. Computer technology, particularly storage devices such as the CD-ROM and advanced forms of data communications, such as the World Wide Web, spurred a renaissance for this method of mapping during the 1990s. However, animation is still not widely used in cartography, has not been integrated in software for Geographic Information Systems (GIS), and faces a number of conceptual and methodological hurdles.
Development of Cartographic Animation. Although many relate the beginnings of cartographic animation to the development of film in early part of the 1900s, it is reasonable to assume that animated maps are as old as maps themselves. Because movement is part of the environment, its depiction was likely a part of illustrations of pre-historic humans. The drawings on cave walls from between 10,000-20,000 years ago have received much attention. Drawn with charcoal, these pictures of animals and other objects have survived because of the protected environment in which they were made. Lost, of course, are those illustrations that were done on a less permanent and protected medium. Drawn with a stick in the sand, an early cartographic animation may have depicted the movement of animals or a fast-moving river.
Maps turned to stone, so to speak, approximately 4,500 years ago - beginning with clay in Mesopotamia and then switching to paper some time later. In many ways, maps are still emerging from a stone-age and a corresponding "paper-thinking" that ties us to a static form of map display. The static map on paper has had a profound effect on the way we represent the world and the way we think about it. Even cartographic animations are influenced by traditional paper maps in the graphic design of the individual frames and their normal presentation as a non-interactive sequence of maps.
Film influenced the presentation of maps as early as the 1930s. A Disney animation from 1940 depicted the invasion of Poland by Germany in the previous year. Arrows, representing the movement of the German army, are shown moving towards the capital of Wausaw and quickly encircling the city (see animation #1). Shown as a part of a newsreel before the feature film, these early animations were an effective means of both education and propaganda.
The film metaphor is still an important part of cartographic animation. Many of the current cartographic animations are implemented as digital movies in either the MPEG or QuickTime formats. While some digital video formats allow the user to access individual frames, they provide very little control over how and which frames make up the animation and how they are shown. Current cartographic animations include little more than play/stop/ forward/reverse controls that we associate with the VCR. The film/video metaphor still ties us to a certain way of thinking about cartographic animation that has been described by the German word "ablauf." Roughly translated, the word means 'an uninterrupted progression from beginning to end.' This limited view of cartographic animation is changing.
Types of Cartographic Animation. A distinction is now made between temporal and non-temporal cartographic animation. Temporal animations show change over time, such as the diffusion of a farming method like irrigation (see animation #2). These animations show change through maps as a time-lapse. An example of a non-temporal animation is the fly-through. Here, a series of oblique views of a landscape are displayed in quick succession to provide the appearance of flying through the terrain (see animation #3). The fly-through is usually constructed by draping a satellite image or an air photograph over a digital elevation model (DEM). A DEM encodes the terrain as a grid of elevation values.
In making the distinction between temporal and non-temporal animation, Dransch (1995) differentiates between "geo-objects" and "animation-objects." In temporal animation, there is a change in the "geo-objects" relative to time. In non-temporal animation, there is a change in the "animation-objects" relative to factors such as a change in the position of the "camera" or light source. However, time is a part of all animations. According to Dransch, "realen Zeit" (real time) is depicted as a time-lapse in a temporal animation, and "Präsentationszeit" (presentation time) is the time used to show the animation, whether the animation depicts a temporal phenomena or not.
Many types of non-temporal cartographic animations have been proposed. A cartographic zoom, for example, shows a series of maps at increasing or decreasing map scales. This form of animation has been the most difficult to automate because it involves all aspects of the cartographic abstraction process, especially the selection and simplification of features. A normal zoom is also possible that does not involve feature selection and simplification.
Other forms of non-temporal animation depict different ways of classifying data. A classification animation shows different methods of data classification, such as equal interval, quantile, standard deviation, and natural breaks, etc. (see animation #4). A generalization animation depicts maps with a single method of data classification but multiple classes (see animation #5). Sound can be added to an animation to accentuate change in the display (see animation #6). The purpose of these animations is to provide a less misleading view of the data than simply relying on one form of data classification.
A spatial trend animation depicts a trend in space over time. An example would be an animation of the percentage of population in different age groups within a city (e.g., 0-4, 5-9, 10-14 years of age, etc). Older populations tend to live closer to the center of the city and younger populations are at the periphery. This type of spatial trend animation for the city of Omaha shows older populations on the right side, closer to the older parts of the city along the Missouri river and younger populations on the left corresponding to the western suburbs (see animation #7).
A set of "dynamic variables" have been proposed that can be used in non-temporal animation (DiBiase, et al. 1992). Reordering, for example, involves presenting a temporal animation in a different order. In depicting earthquake activity, for example, the frames could be ordered by the number of deaths caused by the earthquakes so that the more severe earthquake activity relative to human population is shown first. Changing the pace of the animation has also been proposed to highlight certain attributes. Using the earthquake example, the duration of each scene in the animation could be made proportional to the magnitude of the earthquake or the number of deaths.
These methods of animation are closely linked with cartographic visualization -- an analytical form of cartography that is broadly defined as helping individuals, or groups of individuals, think spatially. This view of cartography is in contrast to the traditional view of maps as a form of presentation. The distinction between 'maps for analysis' and 'maps for presentation' is not clearly defined. Map use is by definition an inquisitive process that incorporates varying levels of analysis. Every map can be used for analysis, even maps on paper that are supposedly designed for presentation. Although a cartographic animation is a "presentation" viewable in time, it, like any other map presentation, only has meaning if it is used for analysis.
Summary. Cartographic animation is an important technique to further our understanding of the spatial environment. It demonstrates that individual maps are only a snap-shot. One should ask: What was before? What will come after? What trends would be evident if the time element were viewed as an animation? The individual map is also a snap-shot in reference to other data sets. What non-temporal trends would be evident if the map were viewed along with other related spatial data? Finally, the individual map is a snap-shot in the choice of representational forms that were used to depict the data. A cartographic animation can provide a more meaningful view of the data through the use of different symbols or different forms of data classification.
Cartographic animation has been limited by both the difficulty of their construction and distribution, and by a continued fixation of the individual, static map. Viewing static maps without interaction or animation is of limited value, particularly in the process of searching for spatio-temporal patterns. Computer technology is making it possible to not only create different types of cartographic animations but also to distribute these animations to a wider audience.
DiBiase, D. (1992) Stretching Space and Splicing Time: from cartographic animation to interactive visualization. Cartography and Geographic Information Systems. v. 19, no. 4, pp. 215-227;
Dransch, D. (1995) Temporale und nontemporale computer-animation in der Kartographie. Selbstverlag Fachbereich Geowissenschaften, Freie Universität Berlin, Berlin;
Peterson, M.P. (1993) Interactive Cartographic Animation. Cartography and Geographic Information Systems. v. 20, pp. 40-44;
Peterson, M.P. (1999) Active Legends for Interactive Cartographic Animation. International Journal of Geographical Information Science. v. 13, no. 4, 375-383.
Cartwright, Peterson, Gartner (ed.) (1999) Multimedia Cartography. Berlin: Springer Verlag;
Dransch, D. (1997) Computer-Animation in der Kartographie. Theorie und Praxis. Berlin: Springer-Verlag;
Peterson, M. P. (1995) Interactive and Animated Cartography. Prentice Hall, Englewood Cliffs, NJ.
© Michael P. Peterson