Geoscience Reference
In-Depth Information
Chapter 14
Relief for Models of Natural Phenomena
Jana Svobodová and Vít Voženílek
14.1 Digital Representation of Relief
Computer models of spatial phenomena mostly use Digital Elevation Models
(DEM) (morphometric characteristics, drainage situation, etc.) to represent the
earth's surface and its properties. The definition of the term digital model of relief
is currently inconsistent both in Czech and in foreign professional literature (e.g.
Šíma, 2002; Voženílek, 2001; Klingseisen, 2004; Longley, Goodchild, Maguire, &
Rhind, 2001; Wood, 1996; Dikau, 1989). Burrough & McDonnell (1998) offer an
apt definition; for them it is any type of representation of the earth's surface continu-
ously changing in space. In technical practice the termDigital Terrain Model (DTM)
is used; however, this term is stricter in its sense (Voženílek et al., 2001). In English
written literature the term Digital Elevation Model (DEM; Longley et al., 2001)
was introduced, and the abbreviation DEM is now used worldwide. To maintain
terminological unity we will use the abbreviation DEM throughout the text.
DEM represents a significant tool in applications processing the earth's surface
and is used in geomorphology, hydrology, cartography, climatology, geology and
ecology. In the last 20 years many studies have been written in the field of digital
relief modelling contributing a lot of information about the earth's surface. Basic
types of DEM are commonly used, namely raster grid and vector TIN (triangu-
lated irregular network). The issue of DEMs is elaborated in detail (Krcho, 1990;
Voženílek, 1996; Wood, 1999; Rapant, 1996; Wood, 1996). However, the difference
in 2D expression of relief on maps that has been used up to now and 3D modelling
in DEMs has not been resolved.
The earth's surface is one of the many existing continuous surfaces. The surface
can express any continuous spatial phenomenon (air temperature, concentration
of substances in the atmosphere, etc.) if the quantity of the given phenomenon is
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