Buildings and terrain unified – multidimensional dual data structure for GIS

3D city models are widely used in many disciplines and applications, such as urban planning, disaster management, and environmental simulation. Usually, the terrain and embedded objects like buildings are taken into consideration. A consistent model integrating these elements is vital for GIS analysis, especially if the geometry is accompanied by the topological relations between neighboring objects. Such a model allows for more efficient and errorless analysis. The memory consumption is another crucial aspect when the wide area of a city is considered - light models are highly desirable. Three methods of the terrain representation using the geometrical-topological data structure - the dual half-edge - are proposed in this article. The integration of buildings and other structures like bridges with the terrain is also presented.