Geoscience Reference
In-Depth Information
2.2 IFC
IFC (Industry Foundation Classes) has been adopted as the BIM data model by
applying the object-oriented method and adopted XML as a method of expression
2
(ISO 10303-13
2004
). This standard data model was developed to support inter-
operabilities among architectures, engineerings registered in the ISO/PAS16739
(
2005
). IFC has defined data elements which represent spatial information and
compositions of spatial relations among indoor features in the building. IFC has
the advantages describing objects of inside buildings in detail.
IFC Building Model describes opening elements and detailed building elements
such as wall, window, and door. The model represents invisible installations like pipes
and wiring. Structure elements have building, building storey and space. The build-
ing may have zero or more floors. Building story is composed of space and building
elements including walls, curtain walls, beams, doors, columns, covering, stairs, win-
dows, slabs, ramps, railings, and roofs. IFC building model represents more detailed
classes for interior building features than CityGML building model. UML diagram of
the building model for IFC is shown in Fig.
4
(Mohamed and Anders
2010
).
IFC model can describe the detailed objects in the building, and it has some
classes for mobile facility. However, the model is focusing on the architectural
elements like beam, pipe, railing, and ramp. IFC model does not have the classes
to manage facility for disaster and convenience, which are not included in archi-
tectural elements. Therefore, it can be used to represent constructed parts of the
building, but it cannot deal with managing indoor facilities described in the previ-
ous section.
2.3 UBM
UBM (Unified Building Model) has developed to integrate between CityGML
and IFC models which are the two most prominent models for representing city
objects in real world (Isikdag et al.
2013
). UBM encapsulates the CityGML and
IFC models, with avoiding translations between the models and loss of informa-
tion. The model has been developed in a way to represent all objects in both IFC
and CityGML building models. UBM considers their ability for modeling spatial
objects (Mohamed et al.
2012
).
UBM is developed in four levels of detail. Boundary surface, building ele-
ments, building installation, wall, level, and covering are described in LoD2.
Building elements are components of storey, opened space, and opening which
are represented in LoD3. The building is composed of one or more floors which
are comprised of spaces on the specific floor. Celling, floor, curtain wall, interior
2
IAI (International Alliance for Interoperability),
www.iai-international.org
.
