3D cadastral visualization and integration of CityGML3.0 with Land Administration Domain Model

Sammanfattning: During the last years, virtual 3D city models have been widely used in application fields such as urban planning, environment simulations, and disaster management. With the development of high-rise buildings and the increasing densely built-up areas, an increasing number of authorities and companies have shown interest in integrating 3D city models with the cadastre. This is because on one hand, the integration can improve the visualization of cadastres and promote the cadastral management. On the other hand, it can enrich the cadastral information in 3D city models and further facilitate spatial analysis. As one of the important standards used in 3D city models, part of CityGML3.0 has been published so far; hence this study is one of the first to integrate CityGML3.0 with the cadastral data model. Considering the challenges of cadastral management, the purpose of this study is threefold: (1) representing physical building objects in CityGML3.0, (2) visualizing legal spaces in 3D models, and (3) validating if it is viable to integrate CityGML3.0 with Land Administration Domain Model (LADM) effectively. For this purpose, an integrated approach was developed, which can also be separated into three parts. Since the format of original data is Industry Foundation Classes (IFC), converting physical building objects from IFC to CityGML3.0 was taken as the first step in this method. And then, legal boundaries were extruded into legal spaces by using a python script and built-in functions in FME Workbench. Lastly, the integration of CityGML3.0 and LADM was implemented. In this approach, a prerequisite was that legal boundaries in the Building Information Model (BIM) should have been connected with physical objects accurately. Based on the proposed method, three results can be derived: (1) transformed building models in CityGML3.0, (2) extruded legal spaces, as well as (3) an attribute table integrated CityGML3.0 with LADM. Among them, the first result suggests that the differences of a building in LoD2 between CityGML2.0 and CityGML3.0 are the definition of feature types and the hierarchy of semantic structures other than the geometrical shapes. And the second result illustrates that it is possible to visualize legal spaces in 3D city models, as long as the legal boundaries can be combined with physical objects in the BIM model. As for the third result, it indicates that CityGML3.0 can be related to LADM without using any extension model. However some details still need to be validated in future as the final specification of CityGML3.0 has not been released.