EN/CityGML-Tutorial/chapter-2:-Building.md

+The building model defines the geometric and semantic properties of a building in CityGML. A building or a building part can be modeled as Solid (B-rep) or MultiSurface. The semantic objects for a BoundarySurface geometry in LOD2 are: RoofSurface, WallSurface, GroundSurface, and ClosureSurface.
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+![CityGML-2](uploads/1d896b57e0343a215e1b404463334145/CityGML-2.png)
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+CityGML also defines attributes for every city object. The standard defines two types of attributes: Schema attributes and generic attributes. Schema attributes are part of the schema definition of each thematic module. 
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+The building schema defines the attributes: function, yearOfConstruction, yearOfDemolition, measuredHeight, storeysAboveGround etc. Generic attributes are defined by the user to store additional information in a city object. There is no restriction in the number or the names of the generic attributes as long as they conform to the XML syntactic rules.
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+* [Chapter 1.1: CityGML Appearance Module](./chapter%201:Intro%20CityGML/Appearance)
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