Managing underground legal boundaries in 3D-extending the CityGML standard

Legal boundaries are used for delineating the spatial extent of ownership property’s spaces.In underground environments,these boundaries are defined by referencing physical objects,surveying measurements,or projections.However,there is a gap in connecting and managing these boundaries and underground legal spaces,due to a lack of data model.A 3D data model supporting underground land administration(ULA)should define and model these boundaries and the relationships between them and underground ownership spaces.Prominent 3D data models can be enriched to model underground legal boundaries.This research aims to propose a new taxonomy of underground legal boundaries and model them by extending CityGML,which is a widely used 3D data model in the geospatial science domain.We developed,implemented,and tested the model for different types of underground legal boundaries.The implemented prototype showcased the potential benefits of CityGML for managing underground legal boundaries in 3D.The proposed 3D underground model can be used to address current challenges associated with communicating and managing legal boundaries in underground environments.While this data model was specifically developed for Victoria,Australia,the proposed model and approach can be used and replicated in other jurisdictions by adjusting the data requirements for underground legal boundaries.