Author Preprint Introduction

Geographic Information Systems (GIS) have been designed in accordance with the way people have conceptualized space (Freundschuh & Egenhofer, 1997). While the reality is tridimensional in nature, paradoxically, its representation has been for long decades dominated by the metaphor of the paper map. This has resulted to two separate models: 2D GIS models and Digital Terrain Models (DTM). “The third topographic dimension is often handled, but only by imposing the assumption that elevation is a function of location, a solution often termed “2.5D” (Goodchild, 2010). Nevertheless, 2.5D representations cannot efficiently deal with representing multi-level structures which might be of interest in some applications requiring higher-dimensional models. Vertical cadaster is one of the appealing examples of applications where a veritable 3D representation is needed. Likewise, consideration of indoor and outdoor objects in 3D models is relevant for several applications such as the evacuation of buildings through the short path in case of extraordinary circumstances (disastrous accidents, terrorist attacks, etc.) (Atila et al., 2013).