The Object-oriented DTM in GIS

The integration of digital terrain models (DTM) in geographic information systems (GIS) implies automatically an extension of the GIS reference surface and its queryspace. It is trivial that a DTM is the natural boundary representation of theearth's surface. Man-made objects, for instance houses, bridges, dams should be considered in a second step because these objects cannot be represented well by boundary surfaces they have to be approximated by solid modelling techniques like boundary representations or primitive instancing. Therefore, an efficient DTM integration in GIS is the first task to be solved. In a first prototype developed in the object-oriented language Python the main features of a 3D GIS will be discussed. Based on this query space spatial operators are derived which are implemented as methods of objects or external functions.