Title : A Surface - Representation Approach to a Three - Dimensional Cadastre

First Paragraph Cadastral systems are traditionally two-dimensional. However, there is now much talk of extending them into the third dimension, in part by incorporating the elevation information in a terrain model. Terrain models have been around for quite some time and so have the arguments between using a grid (or DEM-Digital Elevation Model, in American parlance), or a triangulation (TIN-Triangulated Irregular Network). Usually either approach may be satisfactory-but there are increasing complaints that it is too restrictive, allowing only one z value for each (x, y) location, thus prohibiting the representation of caves, bridges, etc. Nevertheless, computer games everywhere bear witness to the fact that we can represent the most complex monsters-so what are we missing?