ABSTRACT
ABSTRACT: 3D city models and traditional 3D GIS have so far neglected underground structures and features both in theory and practice. Many applications are looking for such integrated approaches, however. In this paper we define a thematic semantic framework for integrated modelling of geographic 3D data, combining man made and natural features above and below the earth surface. Our approach extends the semantic concept and the information model created for the exchange format CityGML by dividing features close to the earth surface into: above, on and below the earth surface. Further, the concept of implicit storage and terrain intersection objects is extended to connect features to a TIN based earth surface model. All features, intersecting or touching the Earth surface, create a full partition on the surface. A suggestion for a possible database implementation of the extended information model is also addressed.
