Linking the legal with the physical reality of 3D objects in the context of Land Administration Domain Model

The massive developments and uses of high rise buildings indicate that the demand for use of space above and below the ground surface is rapidly increasing in recent years. In the context of this thesis, the research is focused on exploring the possibilities of linking 3D legal RRR spaces, modeled with LADM (ISO 19152), with physical reality of 3D objects. The possibilities are explored towards the development of a prototype which is elaborated in two core stages: At first, a physical model is derived from the corresponding conceptual model, using existing national and international standards and then, its efficiency is tested using real world sample data, querying the database and visualizing the result in 3D environment. The conceptual modeling of the proposed model is based on the "people to land" relationship using LADM core concepts described with UML diagrams. Towards the conversion from conceptual model to implementation of a working prototype, the model is first converted into the INTERLIS modeling language, in order to be formally expressed including various constraints in a platform/ vendor neutral manner. INTERLIS is a standard modeling language for geodata exchange which is used to provide more direct implementable models and at the same time support the constraints. The model described, initially, with UML diagrams and especially the constraints in OCL cannot be automatically converted into implementations. During the prototype, emphasis is given at the exploitation of the capabilities of INTERLIS, under the scope of LADM, which is used in actual implementation of land administration system. INTERLIS tools are used to automatically generate implementation components for specific environments; e.g. database schema or exchange file format. Challenges among others during the system's development cycle include the following: how to express the various LADM constraints OCL and semi-formal in standard) formally in INTERLIS, how to include extensible hierarchical code lists in INTERLIS models (not natively available) and distinguish them from enumeration values, how to model 3D volumetric primitives in INTERLIS (not natively available), how to link two models (legal - physical) using cross domain constraints, etc. The system’s development cycle, is illustrated with a proposed model for MLAS in Greece. The model is based on international standards, covering a broader perspective than the existing one used today, including several types of objects and interests that are not currently registered by the Hellenic Cadastre. More precisely, utility networks (both the legal and their physical counterpart), planning zones, marine parcels and 3D (land) parcels are now included at the proposed model and organized appropriately. The different types of spatial units are organized in levels according to the LA_Level structure of LADM, ISO19152. This model is considered as an effort for overcoming these shortcomings, based on international standards, including the representation of a wide range of different types of spatial units, in three dimensions, aiming to establish an appropriate basis for the NSDI of Greece. It is a flexible proposal for comprehensive multipurpose LAS supporting both 2D and 3D cadastral registration in Greece. The prototype is developed in order to evaluate the strengths and limitations of the proposed conceptual model (linking legal and physical objects), as well as to investigate the efficiency and limitations of the existing technological (INTERLIS) tools. The process followed during the prototype development is cyclical and repetitive, providing feedback to the initial model during all the stages and improving it in terms of efficiency, reality and technical implementation. Finally, differences and similarities are mentioned from the comparison of the final (corrected) conceptual model, which results after the evaluation of the prototype, with the initial one. Conclusions and remarks made based on the database queries and visualization, as well as similarities, differences and patterns can be observed between the legal and physical objects. All the design and technical decisions that were taken during the system’s development cycle together with the problems arised, the solutions proposed and challenges for future work are described at the following chapters.