Conceptual modeling of terrain-mapping units

Abstract

This paper indicates the problems encountered applying concepts of semantic data modeling to the description of complex surface objects from a data modeling perspective. The case study discussed deals with the concept of terrain mapping units (TMUs). TMUs are complex relief units. The concept of TMU presents a method for conjunctive data acquisition and data capture for use in geographic information systems (GISs). The definition and selection of TMUs are based on an understanding of the terrain pattern in the 3D photo model. Criteria are given for the delineation and selection of TMUs. The criteria yield a descriptive hierarchical classification scheme for TMUs. The study illustrates that problems arise from subsequently data modeling itself, which presents a simplified view of part of the real-world incorporating to a certain extent uncertainty; the classification (labeling) of the delineated terrain objects comprises uncertainties; and ambiguities in the utilized concepts of a specific application field. These problems have to be dealt with in an integrated approach of data acquisition and GIS database design. This paper attempts to illustrate the necessity of an observation theory for the design of GISs.