Geoscience Reference
In-Depth Information
Hybrid 3D Segmentation Technique
for 3D City Models
Khairul Hafiz Sharkawi and Alias Abdul Rahman
Abstract 3D city model is a virtual representation of a city or urban environment,
where in GIS related context, represents existing cities in the world. Initially, they
are used only as presentations that complement the results of 2D analyses and bear
no analytical capabilities. The advancement in computer graphics technology has
effectively sparked the effort towards realizing 3D GIS where the 3D models can be
used directly in analyses rather than just purely visual enhancement. A lot of
research has been conducted in an effort to provide analytical capabilities to the 3D
models. Rapid developments in computer-related industries have led to cutting
edge technologies that enable analyses to be conducted on the 3D models. The
ability of 3D city models to represent real world objects more accurately have
boosted its efficiency and usability in geospatial related analyses. Now, it has
become the new trend in building and urban management while modelling 3D
objects are getting easier with the emergence of user-friendly tools for 3D mod-
elling available in the market. The Open Geospatial Consortium (OGC) has
accepted City Geography Markup Language CityGML specifications as one of the
international standards for representing and exchanging spatial data, making it
easier to visualize, store and manage 3D city models data efficiently. CityGML
represents the semantics, geometry, topology and appearance of 3D city models in
five well-defined Level-of-Details (LoD), namely LoD0 to LoD4. However,
complex building structures are making the 3D models unsuitable for analyses as it
takes a lot of time to process large data. Thus, it is only logical to breakdown the
complex building into manageable segments. Segmentation is basically a method to
break down an object into simpler parts. This chapter introduces a hybrid 3D
segmentation method based on semantic and geometric decomposition for 3D
