Geoscience Reference
In-Depth Information
LoD1
LoD2
LoD4
LoD3
Fig. 8 Four Levels-of-Detail (LoD) provided by CityGML (images KIT Karlsruhe, K.-H. Häfele
or Gröger and Plümer
2012
). In CityGML, there is also a LoD0. Since LoD0 is more or less
equivalent to the 2/2.5D INSPIRE geometry (LoD0 is restricted to horizontal surfaces, whereas
INSPIRE 2.5D allows for non-vertical surfaces), it is omitted in the figure
Fig. 9 Enrichment of a box representation (LoD1, grey) of a gabled roof building (hatched)—
the terrain profile is depicted brown, a by adding information on the low/high and the horizontal
reference. b Top topOfConstruction, low lowestGroundPoint, horizontal roofEdge. c top
topOfConstruction, low bottomOfConstruction, horizontal roofEdge. d top generalRoof, low
lowestGroundPoint, horizontal footprint
provides a (topologically clean) solid representation and a multi surface repre-
sentation (which might not be topologically clean, e.g. the ground surface may be
missing). See for the UML diagram of the Core 3D profile.
The generalized representation in LoD1 by prismatic block models with vertical
walls and horizontal 'roofs' is enhanced by metadata which denote the reference
for the lower and for the upper side of the block. The values of type Elevat-
ionReferenceValue are used (see
Sect. 3.1
, in particular Fig.
4
). For LoD2 to LoD4
only the lower reference is needed, since the (generalized) actual roof shape is
represented geometrically. In LoD1 and LoD2, the horizontal extension of the
building's shape is represented in a generalized way. To enrich the expressiveness
