REPRESENTATION OF 3-D ELEVATION IN TERRAIN DATABASES USING HIERARCHICAL TRIANGULATED IRREGULAR NETWORKS - A COMPARATIVE-ANALYSIS

3-D terrain representation plays an important role in a number of terr ain database applications. Hierarchical Triangulated Irregular Network s (TINs) provide a variable-resolution terrain representation that is based on a nested triangulation of the terrain. This paper compares an d analyzes existing hierarchical triangulation techniques. The compara tive analysis takes into account how aesthetically appealing and accur ate the resulting terrain representation is. Parameters, such as adjac ency, slivers, and streaks, are used to provide a measure on how aesth etically appealing the terrain representation is. Slivers occur when t he triangulation produces thin and slivery triangles. Streaks appear w hen there are too many triangulations done at a given vertex. Simple m athematical expressions are derived for these parameters, thereby prov iding a fairer and a more easily duplicated comparison. In addition to meeting the adjacency requirement, an aesthetically pleasant hierarch ical TINs generation algorithm is expected to reduce both slivers and streaks while maintaining accuracy. A comparative analysis of a number of existing approaches shows that a variant of a method originally pr oposed by Scarlatos exhibits better overall performance.