3D Data Management - Overview Report

The paper has explored 3D data management from multiple perspective. The focus of the data management issue in this paper has not been restricted to 3D Cadastre, but rather to a broader 3D GIS to ensure that all capabilities and issues that exist in different related fields will assist and affect in the data management of 3D cadastral data. In functional requirements for 3D cadastral data management, the categorisation of 3D parcels at an increasing level of complexity is discussed. This lead to a discussion on options for storing 3D cadastral data in an existing 2D cadastral database that traditionally exists in current jurisdictions. The issues related to adding the time dimension in a 4D cadastre from a database point of view was discussed. A discussion of 3D geometric models based on current research on standards, solid geometry and LADM schema, which in turn led to 3D topological models. The LADM provides a data model that recognises and describes the relationships of a 3D spatial unit to other levels of encodings. BIMS are a good source of 3D cadastral data and has already been used by many jurisdictions. The link between the various geometrical and semantic aspects of BIM vs other data sources can cause differences and issues when data are to be integrated. The current standards such as ISO LADM, GML, CityGML etc. and their inter-relationship were then discussed. In current DBMS 3D capabilities, current software and methods of storing 3D data were discussed which led to a discussion on recent developments of spatial databases and the physical capacity of existing hardware to cope with the large volume of 3D data. The analysis of a gap between what is available and what is needed was based on 3D geometry and topology, validation, standards and ontology, data and hardware, 3D data use and transfer and implementation of a 3D LADM prototype. 3D data management capability and technology exist, however these have not been transferrable to 3D cadastre. The problem is, established cadastre are traditionally 2D and the nature of the cadastral data does not easily extend itself to 3D modelling. While 3D GIS data may be easy to extrude to create a 3D visualisation, because 3D cadastre deals with absolute ownership of 3D spaces it becomes much more complex to convert a 2D database to a 3D operational data structure. The extrusion of 2D to 3D might still be a feasible solution for a cadastre if the purpose is just visualisation, however, if the purpose is to define ownership of defined space, information about the adjoining 3D spaces, checks to determine encroachment or slivers among the spaces, then a simple extrude does not fulfil the requirements