  CityGML is a data model used to represent the geometric and semantic
information of urban 3D city objects. There are several ways to generate 3D
models for applications such as gaming, media content for movies and TV, and 3D
printing among others. Since visualization is the primary purpose of these
methods of 3D model generation they lack the semantic information required for
applications such as spatial data-mining, thematic queries, and geospatial
simulation and analysis. Therefore, there is a need to develop methods for
mapping sematic information of new and existing 3D geometric models and their
conversation to CityGML formats so it can be stored for future use. The
conversion of must allows mapping of classes of objects with a higher
Level-Of-Detail (LOD) such as LOD3 and LOD4 which represent an urban city model
in greater detail. A methodology of the conversion is developed and a prototype
is implemented to validate the algorithms and the methods developed for this
project. The methods can be broadly categorized into three parts a) Extraction
of geometric information; b) Segmentation of the model into various groups for
semantic mapping; c) Mapping of semantic information on the model. Topological
aspects are considered for the mesh segmentation to allow users to easily
select and map semantic information to the geometric model. The generated
models can be used in a wide range of applications ranging from disaster
management to urban simulations such as rooftop solar panel installations.
