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Principles of Semantic Modeling of Landform Structures

DEHN, Martin (martin@giub.uni-bonn.de), GAERTNER, Holger (holger@slide.giub.uni-bonn.de), and DIKAU, Richard (rdikau@slide.giub.uni-bonn.de), University of Bonn, Department of Geography, Meckenheimer Allee 166, D-53115 Bonn, Germany

Key Words: landform structure, semantic modeling, geomorphometry, scale

Landform as a result of various processes acting on the surface is also seen as a static boundary condition for processes in geomorphology, hydrology, meteorology, and others. The description, parameterization, and modeling of landform structures, as well as the definitions of nomenclatures, are fitted to the requirements of the mentioned disciplines, and therefore are often strongly divergent. As a consequence, representations of landform structures of different disciplines often are not compatible and require frequent revisions and adaptations. Being aware of these difficulties, an interdisciplinary Postgraduate School (Graduiertenkolleg) on landform structures was established at the University of Bonn. Within this school, geoscientific disciplines are working together with mathematics, photogrammetry, and computer science in order to derive a comprehensive insight into some of the problems. The presented study is carried out in the frame of this Postgraduate School.

Principles of the semantic approach will be presented in this paper. The main objective is a semantically correct description of landforms that is useful to all disciplines related to surface structure.

The presented approach is not based on traditional terms, such as peak, valley, or hillslope, in the initial phase of definitions; in contrast, it is focusing on geometric forms as a basic property in a much more objective way. Form, position, and the spatial arrangement of forms (topology) are considered. The hierarchical approach is starting with form facettes that can be clustered to form elements based on specific rules. A larger set of form elements can be grouped to landform associations depending on topological conditions that have to be defined based on the theoretical background of geoscientific disciplines. While geometric forms and parts of positions are already defined to a certain degree, topology and the structure of landform components are still a field of research. The outlined basic approach enables the development of a modular modeling framework in which the focus is on semantic representation in the first place and, only thereafter, special features of DEMs, tools, and algorithms have to be considered.

Scale is not explicitly addressed in the basic semantic representation of landform structure. It is discussed if this provides a possibility to apply the concept from small to large scales.