Varioscale TIN based surfaces

This paper focuses on the problem of approximating spatial objects to obtain an ''optimal'' resolution (or accuracy). In traditional map making, the notion of scale has been of vital importance, as one of the most significant components of generalization of geographic entities. However, in geographic information systems (GIS), the notion of scale becomes far more encompassing and complicated than in traditional cartography. The paper introduces an augmented scale concept, by considering spatial objects which are approximations with a spatially varying tolerance, which are referred to as varioscale objects. The rationale behind varioscaling is briefly discussed, and a general strategy for applying this concept on TIN surfaces is presented. A key element of the strategy is to simplify the problem to approximation with a fixed tolerance by using the ''tolerance surface'' to normalize the TIN surface. Two examples are presented, a feature based varioscaling, and a viewpoint dependent approximation.