Characterizing Uncertainty in Digital Elevation Models

Many ecological modeling applications rely upon characterizations of the earth’s surface. In some instances, the actual elevations are important (e.g., see Nisbet and Botkin 1993; de Swart et al. 1994; Liebhold et al. 1994). In others, secondary terrain attributes such as slope and aspect are also critical for the application (e.g., see Huber and Casler 1990; Nemani et al. 1993; Austin et al. 1996; Zhu et al. 1996; Russel et al. 1997). The term digital elevation model (DEM) refers to a variety of digital forms that characterize some portion of the earth’s topography. These are used as proxies for the actual terrain surface in environmental modeling applications. The process of DEM production is one of abstraction, and is subject to error; therefore, a DEM does not perfectly match the real-world terrain it represents. The precise degree of this mismatch at every point is unknown, giving rise to uncertainty about the relationship between data and actual terrain.