Geoscience Reference
In-Depth Information
Fig. 6
Link creating process of the network model.
a
Initial state of node and link tables.
b
Selecting the start node of new link to be created.
c
Selecting end point of new link to be created
For creating connections between rooms and corridors, user selects a sequence
of nodes which should end with a node on a link. In the background of the new
link creation, some processes on the spatial database are carried out. Initial state
of a node table is shown in Fig.
6
a. When user selects a point in the network area a
new record representing related point location is added to the node table as shown
in Fig.
6
b. User is allowed to select nodes continuously unless the selected node is
on a link previously created. As soon as selecting a point on a previously created
link, the link is deleted from link table and newly created links are added to link
table. As seen in Fig.
6
c, an old link between nodes 2 and 5 is removed and three
new links are added to the link table.
2.1.4 Converting 3D Network Model into CityGML Format
Once the network generation process completed, the network data is converted
into CityGML format. We use CityGML's Transportation Module to repre-
sent automatically generated 3D network model. The transportation model of
CityGML is a multi-functional, multi-scale model focusing on thematic and
functional as well as on geometrical/topological aspects. Transportation features
are represented as a linear network in LOD0. Starting from LOD1, all transpor-
tation features are geometrically described by 3D surfaces. Starting from LOD1
a TransportationComplex provides an explicit surface geometry, reflecting the
actual shape of the object, not just its centreline. The different representations of
a TransportationComplex for each LOD are shown in Fig.
7
(Gröger et al.
2008
).
In the study, 3D network data of a building is represented as a linear network in
LOD0. The whole data generation process is described in a flow chart showed in
Fig.
8
.
