Development of navigational structure for buildings from their valid 3D CityGML models

Indoor navigation is an emerging research area. In this paper, a method to develop an indoor navigation structure is presented, given a detailed 3D model of the building. There are many standards for 3D modelling such as KML, X3D, CityGML etc. We used CityGML 3D models to develop a navigational structure for the building. The navigational structure consists of connectivity of spaces and subspaces in a network form and also defines the capacities of the rooms. The graph so constructed can be used in evacuation planning. The 3D model is first exported to a spatial database, such as postGIS. The spatial database of the building, composed of features such as rooms, doors, and corridors, after due structural and semantic validations, is then processed to construct navigational topology. Large spaces need to be decomposed into sub-spaces that can become nodes and linkages between these subspaces need to be identified for defining edges. Edge geometries need to be traced to estimate edge travel times, whereas subspace capacity defines node capacity to hold people during navigations. In this paper, we also discuss the complexity of dividing spaces into subspaces and for edge geometry definition.