Geoscience Reference
In-Depth Information
Fig. 6
3D city database importer/exporter, FME workbench, 3D-PDF
building is the one that is currently in editing. For this building the LiDAR-data and
the DTM are loaded in the right editing window in a 3D-view (Fig.
5
, right). With
few processing steps the operator adjusts the roof style of the respective building
generalized to the laser points with the help of standardized roof structures from a
selective list. The result of each processing step is instantly shown in the 3D-view.
The degree of automatic roof recognition can be expressed by the post-editing
rate. It is basically dependent on the density and the type of the buildings. In mod-
ern cities for example the post-editing rate is only 15 %. The higher the percentage
of historical buildings, the lesser the automatic recognition rate of the roofs. The
post-editing rate can be between 20 and 40 %.
The point density of the laser data influences the post-editing rate as well. In an
area of new buildings with typical German row houses and a laser point density of
approximately 0.7 points per square meter the post-editing rate varies from about
25 % up to 30 %, whereas upon a point density of approximately 4.8 points per
square meter the rate dropped to 16 %.
2.3 Central Storage
The data storage is carried out central on a relational database with usage of the
open source database solution “3D City Database (3DCityDB)”. With a database
scheme (profile) the user has the possibility to create a CityGML conformant data
model in the database. The general CityGML profile was further specialized by
the AdV for a German-wide standardized acquisition of 3D Building Models. 3D
Building Models created with this specializations in the AdV-CityGML-profile
can be saved with a java based importer and exporter in the database and can be
exported and visualized in KML and COLLADA format. Additionally, in Bavaria
a FME Workbench is used to offer the users more data export formats like 3D
shape, dxf, 3ds and Google SketchUp format skp. Since CityGML is an interna-
tional standard and several software companies have implemented products and
interfaces for the geoinformation market a longtime sustainability of this interface
can be expected (Fig.
6
).
